Welcome to my world, my world of turbos, tyre smoke, and tuning...
Tuning cars, driving cars, testing parts, and complaining about everything. It's my job, and a the majority of my non-work life too...
I like Holset turbos, and not in the bizarre bias or weird belief way a lot of car people like certain things, I’m not like that, I just like them because, provided you can source them for the right price, they’re, in my book, and my book is pure fact and no BS or unproven info, the best overall value turbos when you consider power, reliability, spool, initial cost, and repair costs.
The thing is, everyone knows I know Holsets well, and because of this I seem to get about 10 questions a day about them, most of which I’ve been asked 100 times before, and this has happened for years, probably about a decade now.
Having said this, I still also constantly see some right bullshit and misinformation about them from other people too, most of which are people with zero experience of them.
So, to help you guys, and to hopefully reduce the massive amount of questions I get and especially to help reduce the amount of BS I see about them, I’ve decided to make a guide to Holsets and using them on your car...
(Apologies for any minor typos or grammar issues, but I've done this for you lot for free so give me a break lol)
Who are Holset anyhow?
Holset are a UK turbo manufacturer, one of the oldest and biggest on the planet, and have been owned by Cummins for a long time.
They supplied turbos to the tuning scene as far back as the 1970s, and have even supplied turbos for Formula One and Indy Car winners too, but on the whole don’t get actively involved in the aftermarket tuning scene.
The reason for this is simple- They’re a massive company and the commercial market is literally millions of times bigger and more profitable, so they generally leave the tuning scene to the smaller brands.
I personally first heard of them in the late 90s early 00s, and initially thought they were a Scandinavian turbo brand, as I purely saw Holsets fitted to big power cars in Scandinavia, cars making more power than I’d ever seen the same engines make in the UK. But no, they’re actually based in Bradford, but have factories all over the UK and in fact the world- Practically every continent has at least one Holset production facility. Holset factories I can think of off the top of my head are in the UK, USA, Brazil, India, and China, but I’m sure there’s more.
Most turbo manufacturers have worldwide production too, with Garrett having Romania, China, USA, Japan, and many more.
Most are oil cooled, isn’t that a problem?
In a word, no. Water cooling on journal bearing turbos serves zero purpose on a performance engine, and even with a BB core the purpose it serves is debatable, and almost all true race turbos with BB cores (WRC cars etc) are oil cooled only too. All water cooling is for on production cars with long gaps between oil changes is to stop the oil in the core overheating, carbonizing, and gradually blocking up the turbo oil system, when owners shut the turbo off immediately after hard use with the turbo still red hot. This is the reason turbo timers exist and why most of us already know you should at least drive the car off boost for the last minute or so before you switch off.
But they’re not ball-bearing, doesn’t that make them spool slower?
No. ‘Ball bearing helps spool’ is pure sales talk in reality. Even the owner of Xona Rotor admitted this HERE. There’s no friction regardless of bearing type with the engine running as there’s basically no contact; it’s all floating in pressurised oil. Don’t get me wrong, there is a small theoretical advantage, but this is tiny versus the actual things that affect spool on a turbo, ie wheel and housing design, not to mention all the external factors (manifolds, exhaust, mapping, etc etc) which all have a huge effect.
The main advantage is they can take higher thrust loads if all else is equal. Unfortunately, all else isn’t equal, but that’s a whole other story. Basically, don’t worry about it.
Aren’t they ‘old fashioned laggy truck turbos’? My mate said they were...
This is a sure-fire sign of someone who’s talking total shit, either because they’re talking about something they know nothing about, talking from experience of a bad setup, or, which is quite common with tuners- Talking shit about them as they sell a different brand so don’t want anyone to buy one.
Fact is, commercial turbochargers, for any given age, tend to be some of the most hi-tech on the planet, as long as whatever technology doesn't affect long term reliability and is actually a true benefit rather than a sales tactic, as efficiency and reliability is more important to the commercial industry than anyone else, and will pay a far higher price than anyone else to get the best too.
Certain things they won’t have if it’s not needed and sacrifices reliability, but generally, for their age, commercial stuff make a lot similar age tuning parts look very low tech to be honest.
Having said that, of course a typical Holset isn't THE top technology, not at all, but the good ones are right up there, and when it tends to cost 50%, sometimes 25%, of the price of others, but performs almost as well and often lasts longer, it's no surprise they're popular for people for people without unlimited budgets, who know they can spend the saved money better on other more important tuning parts.
Aren’t they all massive?
No. Holsets exist from tiny T2 size ones good for about 250bhp to giants good for about 10 times that. But as the most common applications we see are from large commercial vehicles, plus the fact most people use big ones as they want big power, and famous cars tend to be the big power big turbo ones, make the larger ones far more common than the smaller ones. In reality, it’s the middle sized ones that are most common, the REALLY big ones are rarer than the small ones!
What do the letters mean after the name?
Like, some are HX35, some are HX35W etc?
I won’t bother talking about the earlier Holsets, but for he HX and HY series, W means internal wastegate. G means water cooled (Because most commonly used on compressed natural gas fuelled engines), and V means a variable geometry turbine.
For the newest range, the HE series, W still means internal wastegate, but WG is also used. V still means VGT, but VE is also often used, which means an electronic actuator for the VGT (but it can be used with a mechanical actuator still). Some HEs are called FG, which seems to be non-wastegated, but I’m not 100% on that.
My friend has a HX35, and I have a HX35.
His works great and mine is shit, why?
This is a common one, and happens on all types of turbos, but especially Holsets, and that’s because the name is simply a VERY vague description of the turbo type, and there’s countless variations of each. If I remember right there’s over 650 variations of HX35 alone!
HX35s all tend to have similar turbine wheel sizes, but even then is a few small differences, but can have very different compressors good for over 100bhp difference in peak power, and countless different turbine housing specs, from too small for most cars to way waaaay too big.
All the name will do is give you a rough estimate on the turbo size- Buying a car just because it’s a HX35 or whatever is a massive, stupid, mistake.
Even if you have the EXACT same turbo, that sure as hell don't mean two engines will perform the same! Mapping and almost every aspect of engine spec will affect both spool and power, and SO many engine setups have terrible setups that aren't making the most of the turbo fitted.
If your turbo is performing worse than you expect, it's almost always your fault!
What A/R size is my Holset turbine housing?
Holset don’t use A/R, they, like Mitsubishi, KKK, Trust, and others, use cm2 to measure turbine housing size.
A/R and cm2 isn’t directly comparable, cm2 is a static measurement, A/R isn’t, but you can still get pretty close if you want to compare. On a HX35/GT35 sized turbine wheels, 12cm is generally accepted to be about 0.89 A/R, but the larger the turbo the smaller A/R any given cm2 would be the equivalent of, with 14cm generally being considered to be just A/R 0.80 on GT40/HX40/S300 sized turbine wheels, and conversely, on a tiny turbine a 6cm housing could still be the equivalent of A/R 0.80.
Because of this use your common sense, use your eyes, and do your research. A 25cm HX55 might sound like a super huge housing when you’re used to 9cm housings on HY35s, but a HX55 is practically twice the size and a 25cm housing is probably only about a 1.10 A/R on that size turbo.
You can use the housing sizes on other stuff as comparisons too. With most Subaru turbos using cm2, and Mitsubishi Evo ones also, you can compare those to the similar smaller Holsets.
And for bigger ones, well the famous Trust turbos used on countless big power Japanese cars used cm2 as well. The T88 34D, a 1000bhp capable unit, like an older fashioned version of a HX55, and often seen on Skylines, Supras, and RX7s, tended to be a 22cm housing, as was the 38GK version. The Trust T78, a 700bhp turbo, so HX40/HX50 size, but older fashioned, was generally 17 to 24cm housings. The Trust T67 turbo, similar to a HY35 in capability, but again, older design, also had similar housing sizes, 8cm and 10cm most commonly, but 12cm and 16cm was also used. Even Trust’s version of the TD04, good for ~300bhp, used a 8.5cm housing; though I’ve seen at least 380 using a TD04-based turbo with a 6cm housing; it’s all down to the right housing for the right application.
Can I use the internal wastegate?
On a diesel, yes, no problem. On a petrol, well it’s debatable. On the smaller turbos yes, defo. But for bigger ones, personally I’d not take the risk as they’re pretty small and you could/would suffer with boost creep. But oddly I’ve seen people use them, even on HX35s and HX40s, with perfectly good success; but I’d not take the risk, just go external.
As a side note, the 'G' versions, ie the water cooled ones normally fitted to CNG fuel engines, often have a VERY large internal wastegate- They MAY be perfectly fine to use on a petrol car without boost creep, but I can't confirm. Certainly better than most!
My manifold is single scroll but the turbo is twin scroll, can I still use it?
Yes. Fitted to a twin scroll manifold will help spool, 500-1000rpm faster on average, but you can use a twin scroll manifold on a single scroll manifold no problem. BUT I’d highly recommend you port match it to suit, including smoothing off the divider so the exhaust gas isn’t hitting a flat surface, which is bad for both spool and power.
When will the turbo hit full boost?
Well I’m going to talk about this in the next section, and this is a bit of a 'how long is a piece of string' question, but peoples obsession with ‘full’ boost is wrong. Some boost and full boost can be 2000rpm+ different from each other, especially on bigger turbos, but they’re often absolutely flying long before full boost, and boost pressure itself isn’t a pure sign of power.
On my Skyline RB20 for example, I originally had a Garrett GT2871R, and swapped to a Holset HY35 based turbo, which is good for about 150bhp more, a much bigger turbo. The GT2871 was at 15psi by 3500rpm, by then the HY35 based turbo was at about only at 8psi at the same rpm, but still pulling MUCH harder despite less boost. And while full boost (23psi or so) wasn’t until 4000rpm, it was making positive boost and accelerating nicely well under 3000rpm.
My turbo's meant to be good for up to 600bhp, but I only got 480, that’s shit?!
That’s nothing to do with Holsets, that’s not even a turbos fault, that’s your fault for not understanding turbos and turbo sizing.
A turbo may be able to hit 600bhp maximum on the right engine, but without enough boost, or if you fit it to an engine far too big or with poor airflow, you’re not going to hit the peak numbers, possibly not by many hundreds of bhp.
This is the case with all turbos of all makes, in fact it’s worse for many such as these new Garrett turbos with tiny turbines and big compressors, so you need to know what the hell you’re doing.
The less boost you want to run for any given power, the bigger the turbo you will need.
The bigger the engine you have, the bigger the turbo, especially the turbine side, you will need for any given power.
HX35s and HY35s for example- Both are well proven at 600bhp on cammed 2ltr engines at 30psi+ boost. But go up to about 2.5ltr and I don’t recall seeing anyone manage more than 550bhp with one.
How do I find out what the spec of a Holset turbo is?
Well, that’s not easy. This is the main reason, unless you’re a geek like me who can spot a spec from a few pics, you’re better off buying from a proven specialist like Compressor Racing who gives you the detailed spec with every advert.
As already said, there’s literally hundreds of variations of each kind of Holset, so a name means little, and even the part number won’t help much as Holset themselves won’t help you, and details of components aren’t publicly available. Dealers have a part number database, but they guard it like their lives depend on it, and even this doesn’t have details like wheel and housing sizes; more of a use as a cross reference than anything else.
The main thing you can do, aside from a general estimation from what it is, ie HX35, 40, whatever, and this is usually the most important factor as generally modern Holsets are all good wheel specs, is knowing what turbine housing size you have.
If you look just inside the turbine inlet flange, you’ll see a number, 7, 12, 25, whatever. That’s the turbine housing size in cm2. If you can’t see that number, you usually can read it on the outside as a combination of the other numbers. Usually a number printed after the main part number.
I’ve got a T4 flange Holset, but the bolt holes don’t quite line up with my T4 manifold flange?
That’s because most Holsets, in fact most OEM T4 flange turbos, use T4i or T4 International, which is almost the same, but the bolt holes are like 3mm out. I never understand why people worry about this as it takes all of 10min to elongate holes ever so slightly so it fits, and many manifolds have bolt holes big enough that you don't need to at all, but some people do get confused...
What about the VGT variable geometry turbos?
Are they any good? Can you use them on petrol engines?
Can the VGT be easily controlled?
In a word, to all of these, yes, and in fact they’re arguable the best variable geometry turbos in the world. Why are they the best? Well aside from using the usual Holset wheels etc which are great, and the fact VGT can speed up spool by as much as 1500rpm, they solve the main issue that people are wary of when it comes to variable geometry turbos- The fact they’re fragile, suffering from sticking vanes and unable to take the high exhaust temps of petrol engines.
Well Holset VGT works differently to most, as instead of a huge number of moving parts and fragile vanes, the vanes are fixed and instead the main body inside the turbine housing moves up and down to change the effective housing side.
This design change makes them far more robust than usual variable geometry turbos, to the extent it’s very rare to see the VGT system fail unless it’s due to a serious failure that’s also damaged the turbine wheel, and in these cases even a conventional turbo would have the same issues.
Does this mean they can be used on petrol engines? Well yes. It’s still rare, but has been done many times in the USA, and I’ve seen these turbos on 4G63s, 2JZs, Saab 4cyls, and even 13B rotaries. I helped build a Mercedes V8 using a Holset VGT turbo in fact, check that out HERE.
Controlling them is pretty easy too, but you’ve got a few options. There’s two kinds of Holset VGTs, ones badged as ‘V’ and ones badged as ‘VE’ but when it comes down to it things are similar. ‘V’ ones are the older style and intended from the start to be operated with an actuator. Just like most diesel actuators, they are vac actuators, but it doesn’t take a genius to change them for a pressure one, and in fact I’ve seen someone cut the top half (and half the valve!) off a cheap external wastegate, and weld it to the actuator rod, to make a very cheap but effective pressure actuator for one of these turbos that fitted all the OEM mounting brackets.
The most complex, maybe overly, but it is very clever, was the guy who used the VGT turbo on the Saab 4cyl. He used two actuators joined to a central adjuster wheel (I can’t think of a good word to explain it lo), one a vac one, one pressure, so while the pressure one opened it as normal, the vac one opened it slightly when off throttle and at a cruise, lowering cruise EGTs and increasing fuel economy- Overkill for most performance applications, but very clever!
For what it’s worth, despite using a very big VGT turbo, he had no issues spooling it mega fast and if I remember right found that he only needed to set the VGT to open by about 7psi, and beyond that it spooled super fast even with the VGT fully open.
You don’t even need an actuator, and in fact many don’t. One of the most effective ways of controlling a VGT, and is in fact a lot of OEM ECUs use this as part of the VGT control strategy, is to base it on pre-turbine backpressure. So as backpressure increases, the VGT turbine opens up to keep it in check at a sensible level. This is done in motorsport a lot too with conventional turbos, as it’s a very good idea, and something that would be done more often if cars had pressure sensors in the exhaust manifold etc. In fact you can see Ferrari doing it with their Formula One turbo engine HERE. Anyhow, this sounds complex, right? Well no, to do this is one of the most basic looking ways possible, so much so it looks like a bad idea, but done right works great, and that’s just using a spring. You simply are using a spring to hold the VGT in the fully closed position, and exhaust backpressure will, at whatever level the spring tension is, overcome the spring to push the VGT open. Of course this takes a little testing and trial and error, but it’s not tricky and we found the suitable spring rate almost straight away when we did the aforementioned VGT Mercedes AMG V8.
So, what about the ‘VE’ version? Well, the above options all work and are used, but as standard these are controlled fully electronically by a motor on the side of the turbo- E for electronic, see?
Anyhow, these electric motors, while expensive as hell to buy, work well, and while in OEM use are controlled the stock ECU, these days there’s loads of programs and hardware which allows them to be controlled easily.
BUT what if your VE hasn’t got the control box? Loads don’t. Well as said, you just use the conventional methods, it works just the same and in aftermarket use I think there’s a lot more VEs using conventional mechanical VGT control than ones using the electronics!
The only thing you need to do is weld/tap/whatever a bolt or piece of metal or whatever to the VGT arm to allow an actuator or spring to be attached to it, because as standard it’s a small toothed arm. 2min job really, easy.
Final thing worth noting with these VGTs are most the HE341VEs and HE351VEs use a funny turbine inlet flange, rectangle, but longer than a typical T3 one etc. That would normally be a pain in the arse, but they’re so commonly used in the USA that companies make and sell the flange, like THESE FOLK...
Also, if you want a sexy billet HE341VE (basically a billet VGT HX35), they’re available HERE.
'Hybrid' or 'Custom' Holsets-
To be honest, hybrid turbos made from Holsets are pretty rare, especially as the big draw of Holsets is they’re so good, and well-priced, as standard, so there’s not a lot of need to make hybrids.
Having said that, they do exist and tend to be pretty good.
I’m very sceptical of hybrids that don’t even use a Holset compressor wheel, as the big advantage of Holsets tends to be they make big power for any given compressor inducer size vs many other turbos, so changing to a bigger wheel of another brand may not be the advantage it looks, no matter how shiny and billet it may be.
One of the most common hybrids is a HX35/40, so a HX35 turbine side and bigger HX40 compressor. This is pretty easy to make as many HX35 and HX40 parts are all interchangeable, so you simply fit the correct spec (not all are compatible, but that's another story) HX35 turbine wheel and housing to a HX40 and job done. I was surprised to find from a friend’s car running one he lost around 700rpm spool versus a straight HX35 though. Holset themselves make what is really a HX35/40 with most (not all!) versions of the HE351 being just that.
Some of the best hybrids, in my eyes anyhow, are the ones that don’t mess with Holsets wheel combinations and just change housings to more useful ones. Things like the Bullseye Power ones that made HX35s direct fit to Mitsubishi 4G63 engines, Tim’s Turbo ones allowing them to direct fit Porsche 944s, and things like the Compressor Racing RS341 are good and well proven examples of this.
I'm not 100%, but I'm 99% sure Holset HE221Ws can be direct swapped to use the turbine housing of some (not many, most are too small!) OE Volvo and Saab engines, and I think there's a housing available to make them fit a Subaru flat4 too...
Technically you could class turbos with the turbine housings swapped for rarer/smaller versions are hybrids too, like the rare 11cm non-wastegate Holset HX35 ones HERE.
This is a weird subject, as people get really confused about something that’s not complex at all.
I see a LOT of turbos people legit think are genuine Holsets, despite not having a single Holset marking on them at all- That’s clearly not real. The exception to this of course is hybrid turbos using non-standard housings of course, but you should know that.
At the same time, I see a LOT of people where people question if it’s a real Holset, despite being covered in Holset markings etc. Don’t get me wrong, it’s ‘possible’ for fake ones to be covered in real branding, but in my experience of messing with, using, buying, and selling Holsets for over 15 years now, if it looks like a real Holset, it’s highly likely it is. The exception to this, well I don’t know for sure, but I’m sceptical, is Chinese sellers of what looks like legit Holsets. They may be real, some of Holsets biggest production facilities are in China, but I don’t like to take the risk when I can source them closer to home- Personally I won’t buy a Holset direct from China no matter how real it looks.
Who’s safe to buy off?
I think this can be summed up with “Any well proven company”. In the UK the Holset specialist seller from an aftermarket tuning point of view has always been Compressor Racing, they've been around for years, supplied thousands of Holset turbos to people, and while there’s other specialists in other countries, I’ve never personally dealt with them so can’t comment on that, but I expect you non-UK guys know them.
Used ones are a gamble, but a gamble I often take if they’re cheap, as they’re strong turbos so tend to be broken far less than other brands lol.
Having said the above, I have still been stung buying what was meant to be 'good used' ones from a certain Polish eBay seller who often has a lot of Holsets listed- In reality it was a badly worn one sprayed with silver paint to not look too shit in the pics. Live and learn there.
What about the unusual flanges some Holsets have?
Quite a lot of Holsets have v-band compressor outlets and while most have v-band turbine outlets so easy to sort by just buying a v-band off eBay or anywhere, The Holset HX2* and HE2** series have 4 and 5 bolt outlets that look like Garrett T/GT/GTX2* outlets, but aren’t quite. And a few turbos, the HE341VE/HE351VE especially, have an unusual turbine inlet flange too.
A lot of people make a big deal about this, but in reality it’s very basic, and in the grand scheme of fitting a custom turbo setup to your engine, it’s even less of a big deal. Holsets are incredibly common in tuning, especially in the USA, so all parts are available.
For the 4/5bolt turbine outlets mentioned- You’ll find various sellers advertising the OEM outlets for pretty low cost, but generally these aren’t exactly high flowing and may well not suit your engine bay layout. You’ll also find various sellers (non-UK but that doesn’t matter these days) selling the plain flange, which is a way better idea as it allows you to knock up a custom downpipe to suit your car perfectly. But these days, with engineering shops and CNC machines on every street corner (ok not really, but they’re not uncommon), getting a custom flange made up locally isn’t exactly tricky either.
For the compressor outlet flanges- Again you can just buy the adapters from various places all over the world, even from Cummins UK you can buy them for about £65, but in all honestly most don’t bother. Many simply spend 10min with a Dremel or similar machining the v-band lip down to just be a small lip for a conventional silicone hose and Jubilee clip. And the other option, and to be honest what’s done on most turbo setups even if the turbo does have a normal hose fitment outlet, is just get whatever suits you welded on to the compressor outlet. Removing the housing is a 5min job, welding the perfect outlet for you on to the housing is a 10min job for a TIG welder, and getting this right no matter what turbo you have is usually better than having a compromised setup just to use the stock outlet.
Finally, while I've already covered this earlier in the feature, the turbine inlet flange- Almost all Holset are just the usual T2, T3, T4, and T6 flange, though many T4s are T4i, which basically means 2 of the 4 bolts are literally half a hole, ie a few mm, further out. Many manifolds have big enough bolt holes to take this in to account, but it’s literally a few mins with a grinder or similar to oval two of the holes slightly, so no big deal either way.
The most common turbine inlet flange issue is for the very common and popular HE341VE/HE351VE turbos. These use a rectangle flange, but it’s neither T3 or T4, but thankfully as they’re so common and popular in the aftermarket, plenty of companies in the USA sell these flanges, and even adapters to go from T3 or T4 direct to this flange.
There’s a huge range of Holset turbos out there, countless ones over the decades, and there are many hundreds, sometimes well over 500, variations of each version, but here’s the general lowdown on each kind…
The HX/HY series-
By far the most common type of Holset you’ll come across, and the equivalent of Garrett GT series, though in some respects actually more advanced and more capable.
HX20- According to Holset literature, the compressor, at least the biggest version, is good for 275bhp, making it similar to a Mitsubishi TD04, a turbo it shares a lot of components with. HX20s are very rare though, and I honestly don’t recall seeing one in my life to be honest, on an OEM or tuned engine...!
HX25- Again, this shares many parts with the Mitsubishi TD04 series, albeit bigger compressor and turbine wheels than the HX20, and is capable of around 290bhp. Usually internal wastegate, T2 flange, and often with a ported anti-surge inlet, it’s a good and very compact turbo, but rarely used in tuning still to be honest. You can consider all of these HX2* series turbos higher spec versions of Mitsubishi TD04s, and can use them accordingly. HX25s spool fast even on 1.6ltr engines, for example.
I've actually got one of these for sale HERE
HX27- The biggest and most commonly used of the HX2* series, again very compact and T2 flange, it’s pretty much the equivalent of a Garrett GT28RS, and spools very very quickly even on 1.8ltr engines. Good for roughly 350bhp, it lives in the shadow of the more popular HE221W, which while slightly more powerful, is a similar turbo.
Check out the vid below of one fitted to a 1.8 20VT engine in a Mk2 Golf- It seriously moves for a little turbo!
HOLSET HX27 at 20psi- Mk2 Golf GTI
HY30- Honestly, I'm unsure about these, as they are very very rare, one of the very few I’ve never seen in person. They’re likely good for ~350bhp or a touch more on the right engine, as HYs normally have the HX version compressor and smaller turbine side, somewhere between HX27 and HX30, so it could well be a great turbo. Pics I’ve seen seem to show HY30s as T2 flange, but I’ve never seen one in person to be honest.
HX30- Quick spooling and compact T3 flange turbo. About the size of a Garrett T3, but certainly more capable and advanced than them. Good for up to 460 for at least one version according to Holset, but most versions you see available 360 or less. They are all T3 flange on the ones I’ve seen, from single scroll 6cm to twin scroll 12cm housing versions. They’ve often got an anti-surge compressor inlet, but not always, and there’s at least three different compressor wheel sizes that I’ve seen. Very fast spooling, I’ve seen 9cm versions spooling as fast as T28s on 2ltr engines, and making more torque for any given boost pressure too, though most don't make much more than about 350bhp.
Bigger turbine wheel than a HX27 or HE221 but generally capable of same sort of power levels.
Here's a YouTube video of a Golf GTI claiming 380 from a HX30, and it certainly doesn't look slow...
Golf GTI HX30 380BHP
HX32- Very rare turbos, but very good, and capable of up to about 500bhp, limited by turbine flow. These are in essence Holset built HX30/HX35 hybrids, as they use a HX30 turbine wheel and a HX35 compressor wheel, albeit often the smaller versions of the HX35 compressor. They come in various forms, from 12cm twin scroll housings to 6cm single scroll and everything in between. They’re almost all T3 flange but some T2 as well. Spool is very fast, somewhere between a HX30 and HY35, and while these have always been considered somewhat of a holy grail ideal turbo for tuned cars, they’re that rare that I’ve not seen a huge amount of results; mostly people saying they’re very impressed with theirs!
Here's some HX32 Videos below...
RB20DET with a HX32 in a C32 Laurel doing a pretty badass burnout
In-car hillclimb action with awesome turbo sounds of the above RB20 Laurel
Astra VXR with 12cm HX32 vs Supercharged Civic Type-R
Astra VXR with 12cm HX32 vs 371bhp Astra VXR
HY35- This is personally my overall favourite of the Holset range, proven good for as much as 600bhp on big boost well specced 2ltr and under engines, seen as much as 540bhp at 1.5bar on fairly stock 1JZs, and very fast spooling for a turbo capable of this much power too- People have seen full boost by just 3000rpm on well mapped and well set up 2.5ltr engines.
In the USA these are most commonly found with a 9cm single scroll T3 housing, and in the UK/Europe mostly found with a 10cm single scroll T3 housing, but in the grand scheme of things 9-10 makes very little difference either way.
Compressor wheel wise, they’re basically the 7blade HY35 compressor side almost always. Turbine wheel size, it’s half way between the HX30/HX32 turbine wheel and the HX35 turbine wheel.
The now pretty famous Compressor Racing RS341 is, for all intents and purposes, a HY35 variation, and as a comparison, I had a GT2871R on a RB20, and swapped to an RS341. The 2871 spooled faster, made 15psi at the same rpm the 341 made 7psi, BUT it didn’t matter, as despite about half the boost pressure, the 341 made the car pull noticeably harder, and once boost was at the same level it was like night and day; massively more power. So yeah, while these spool fast, with bigger turbos there’s a lot more to performance than simply what boost pressure it hits at what rpm.
HYs have become pretty thin on the ground lately, but they’re still out there.
Oh, and a 7cm T2 flange HY35 exists too, albeit damn rare. These have slightly smaller compressor and turbine wheels than the normal HYs, in fact it’s surprising it’s not called a HX32, but that’s the huge variation with Holsets for you.
Check out these HY35 YouTube videos below...
2.8ltr Saab V6 with a HY35 making 480@wheels (so well over 500 fly) on stock internals.
My old RB20 R32 Skyline with a Compressor Racing RS341 running 1.5bar...
FWD Mk2 Golf road car, 1.8 20V running a HY35- 10.4sec quarter mile at 135mph!- Likely 550bhp+
HX35- This is the best known and most common Holset on the tuning scene, and the equivalent to a GT3582R, with almost identical wheel sizes in fact. Spec for spec, same housing sizes, they actually seem to spool better- Have you seen a GT35 hit 25psi by 3500rpm on a 2ltr? I haven’t at least, but plenty of twin scroll HX35 setups have.
There’s an insane amount of variations of HX35s, 650 plus at last count. There are compressor inducer diameter sizes down to about 50mm (I’ve heard of smaller, but no proof), which would lower its power potential, but the most common ones, and the ones to go for, are the 54mm inducer 7 blade compressor, and the 56mm 8 blade inducer, both proven at 600bhp. There are rare 6 blade versions too, which theoretically should flow more for any given inducer diameter, and billet versions too, but seen no data that they’re capable of more.
Most have 82mm compressor exducer, but many later spec ones have a 76mm exducer, but it’s unlikely to affect peak power and seen no proof either way.
There’s a wide variety of turbine housings out there, but the best known one in performance terms is the 12cm one, though I’ve seen 6cm undivided T4, 8cm and 10cm divided T3, and many more. Generally 11cm to 16cm housings suit the majority of applications, with 11-12cm best for 2.5ltr and smaller engines, and 14-16cm best for larger engines. The oddball small ones, 8cm, 10cm, are great for spool of course, but don’t expect to be getting 500bhp+ from them, partly as the turbine won’t flow as much, but also because they tend to come with smaller compressor wheels too.
I’ve personally never seen a HX35 hit 600bhp on larger than 2ltr engines, but seen it on 2ltr and smaller engines many times, with the 4G63s in the USA hitting it most commonly, at 30-35psi. The most I’ve seen from 2.5-2.8s with HX35s is around 550bhp, and a little less on even larger engines.
Spool-wise, a 12cm on a 2ltr with a twin scroll manifold is well proven to see 25psi+ by around 3500rpm, which is fantastic for a turbo of this size. Using a single scroll manifold and a 2ltr I’ve seen more like 1000rpm slower spool, 4500rpm, but still no lag between gearchanges, and some, just not ‘full’, boost long before then. On 2.5ltr engines, the 12cm housing even with a single scroll manifold tends to be full boost by around 3500rpm.
This is a good YouTube video that shows spool with a twin scroll manifold and a 12cm housing on a well set up 2ltr engine-
HX35 on Mitsubishi 4G63 engine spool
HX38- “Oooh, a HX35/40 hybrid” I hear you say. Yes, but unfortunately the wrong way around! This, on every one I've ever seen, is basically a HX35 compressor side and the bigger HX40 turbine wheel. Pointless/useless for tuned cars unless you want low power for your capacity. Avoid.
HX/HY40V- I’ve seen these called both HX and HY40s despite the same basic spec, but this is the VGT version of the HX40. Generally tends to be T4 flange, and pretty much the typical HX40 spec, just VGT.
I’ve seen very little info on this turbo, BUT going by the video below, it has no issues spooling up even on an ancient spec 2.4ltr diesel engine, in fact this is cool as fuck!
Mk1 Ford Transit 2.4 diesel running Holset HY40V!
Effectively like the slightly bigger brother of the HX35. Good for up to 700bhp with the 60mm compressor inducer, though there are smaller compressors on many HX40s you see, with the 58mm is most common, and still good for 650odd. They come in T3 and T4 flanges, 14cm T3 is the smallest generally available housing, 16cm relatively rare but more common. Not a big step up in wheel sizes to the HX35, and the overall turbo size is pretty much identical too, so they're a good way of going another 100bhp over what a 35 can do without big changes to your setup.
Some badass engines run HX40s, as these videos show...
Audi TTRS engine race buggy making 700bhp with a HX40
BMW 4ltr V8 making 550bhp at the wheels at 0.9bar with a HX40
HX50- HX50s come in a very wide variety of wheel sizes, from only slightly over 700bhp capable, to some just as big as the biggest HX55 wheels; pretty much 1000bhp capable units. They have a variety of turbine wheels too, most somewhere between HX40 and HX55, but some being pretty much full HX55 size, making them essentially HX55 turboss albeit in a much more compact frame- HX50s are externally only about 2/3 the size of a HX55, making fitment easier.
The hardest thing with HX50s is finding them with small turbine housings. 17cm and 19cm housings are the smallest I remember seeing, but they’re rare, and around 25cm is the most common size. For a larger engine, 3ltr+, or a very high revving engine like a Honda, these big housings aren’t an issue, and a 25cm housing is still a quick spooling turbo on a 4ltr engine, but it does make it tricky to find quick spool housings if you’ve a smaller capacity engine.
Check out some HX50 videos...
Honda Civic with B18 engine making over 920bhp on a HX50!
Toyota GT86 running a 4ltr 1UZ engine and a Holset HX50 at 15psi- Smoke machine!
HX52- Like a giant sized HX32 or HY35, the HX52 has the big boy HX55 sized compressor wheel, usually 65/66mm inducer, but a much smaller turbine wheel, smaller than many HX50 ones in fact, making for a very fast spooling turbo for its size.
Unlike HX50s, HX52s always come with a small turbine housing, usually T4 flange, with 16cm the biggest most common size, 13cm being another and usually internal wastegate, and 11cm being the smallest and rarest; though I know of at least two variations of the 11cm housing, one T4i flange and one a weird flange. They take up more space than a HX50 as they have HX55 size compressor housings, despite much smaller turbine housings. Considering they’re good for the best part of 1000bhp when pushed hard on the right engine they spool fantastically well too- On a 2.9ltr, using a single scroll manifold, and the 16cm housing, 15psi comes at just 3750rpm- With a good twin scroll setup you’d likely take at least 500rpm off that, and then there’s the option of the smaller housings…!
I'd have no issue at all running one on even a 2.5ltr drift car, in fact I really wanna.
There's quite a few cool HX52 videos out there, and here's my pick...
HX52 16cm spool on a 2.9ltr VR6 engine and a single scroll log manifold.
HX52 16cm making 800bhp on a basic spec 2ltr 4G64 and cast manifold!
HX52 16cm on a M50 BMW engine sounding pretty damn awesome
HX52 on a SR20DET making 800bhp at the hubs
HX55- This is the equivalent of a Garrett GT42 or BorgWarner 9180, the HX55 is capable of around the 1000bhp mark when pushed hard, though I’ve seen a couple of people claim 50-100bhp more than that. Housing wise, the smallest you commonly see is a 19cm internally gated housing, and then there is 22cm and 25cm non-wastegated housings also quite commonly found. I know of an 11cm housing version but that is rare, and while most are T6 flange, T4 versions exist.
Most HX55s have v-bands holding both the compressor and turbine housings on, but there’s a less common version with a bolt-on turbine housing, which I’ve seen 22cm and 25cm T4 flange housings for.
For their size they’re impressive bits of kit, and on 4ltr engines like 1UZs they make serious power from just 3500rpm on even with the biggest 25cm housing, which is well impressive for a turbo good for 4 figure power numbers!
Check out these HX55 videos below-
833bhp at just 1.5bar from a HX55 on a BMW M50 engine in a stunning E36 BMW
950bhp HX55'd 2JZ Soarer
R33 Skyline drift car running a stock bottom end 1UZ and a Holset HX55 25cm. 640bhp at the wheels at just 1.3bar, 600nm torque by just 3800rpm
HX/HY55V- As with almost all V/VE Holsets, the HX/HY55V is basically just the VGT version of the HX55, with identical wheel sizes and so on. They’re usually T4 flange, with some HY55 versions coming with a twin scroll inlet, despite the housing not actually being twin scroll.
This is the turbo we used when we built the 'boot mount turbo' E55 AMG I helped create for Compressor Racing a few years ago. Despite being mounted 12ft away from the engine, with the exhaust going through restrictive silencers pre-turbo, no heat wrapping, and loads more things that slow spool down massively, it was on full boost by under 3500rpm, which nobody would've imagined for such a huge turbo mounted in the boot if we didn't prove it!
Click here for the video of the rear mount turbo E55 AMG.
These beasts, while many only physically a little larger in external diameter to the HX55, are rated at up to 1260bhp by Holset, and with tuned cars out there running them and making anything from 900 to over 1200bhp, they're certainly not wrong.
Some of these I've had dealings with had directly interchangeable parts with HX55s, enabling hybrids much in the same was a HX35-HX40 hybrids, but I don't think that is the case for all of them.
Rather than waffling on, check out these YouTube clips...
Audi 5cyl making over 1200bhp with a Holset HX60!
RX7 making 900bhp at the wheels with a HX60
Volvo 850 making 950bhp on the dyno with a HX60
In car acceleration with the above Volvo 850- Insanely fast!
HX80- Usually found on medium size fishing boats and similar as an OEM turbo to their giant engines, most HX80s are practically dustbin lid sized units, but slightly smaller units that almost resemble (the still huge!) HX60s, and HX80s have been seen on 1600bhp+ drag 2JZs, 5ltr+ V8s, and even 6ltr diesels giving full boost by around 3000rpm, they’re surprisingly usable considering their huge size!
This Supra on Speedhunters is rocking one of the more 'normal' looking HX80s...
HX82- The big daddy. Basically a HX80 with an even bigger compressor, and just like the 80 it’s most popular in the extreme tractor pulling crowd. The HX82 is physically about the largest ‘normal’ turbo out there of any brand, as bigger things like found on trains and ships and similar might be turbochargers but they tend to be hugely heavy and bulky, and barely resemble turbos as we know them.
This giant size means they’re not only popular in tractor pulling, but have recently became the turbo to have for certain drag racing series where a single turbo allows a 200kg less minimum weight limit vs twin turbos, leading to world famous drag racers such as Larry Larson, Birdman, and Shawn Wilhoit, all going for heavily modified HX82 based turbos for their drag cars, and looking to make around 3000bhp!
HX83- This is an odd one, and while I don’t know a huge amount about it. The ones I’ve seen have been a giant version of a HX38. What I mean by that is they had no bigger compressor than a HX82 or even HX80, but an even bigger turbine side. Many I saw even had cast iron compressor housings, so would weigh a ton. I don’t recall ever seeing a HX83 in a tuned application, and if they’re all like the above ones I’ve seen, I’m not surprised.
HX85- I honestly don’t know much about these aside from they’ve got a very limited range of applications even as OEM, and they look much like the HX83 where the turbine looks huge without a particularly big compressor, 51cm turbine housings etc, making them unlikely to be chosen for any aftermarket use. The fact I’ve seen these for sale by tractor pull guys for far cheaper than HX80s, but also never seen one used on any tuned vehicle, even a tractor puller, suggests they’re probably to be avoided.
The Holset HE Series turbos
The HE series is the successor to the HX series, and while in the most part are the same basic turbos with either minor changes, or simply renamed, some versions have cool new technology fitted to them. The HEs tend to have smaller turbine housings than the HX too, which is good for a lot of tuned engines.
The main problem with the HE series is it makes the already vague HX naming system even vaguer!
In earlier HE series it was less of a problem, as the first digit was the general frame size, and the second was the general compressor size, so a HE211 and HE221 was the same basic size, but the compressor especially on the 221, was bigger. There’s a few examples of this on bigger ones, mostly VGT ones, where the compressor is fairly small for the turbine size, HE531 for example, but again, the numbers help signify that.
Unfortunately the newer HE turbos, things get super vague with turbos good for hundreds of horsepower different, all having the same name. HE200 covers all the small frame T2 flange turbos. HE300 covers everything from sub 400bhp to 600bhp+. What was HX30/HX35/HY35 and some HX40 turbos. HE400s cover what would’ve once been HX40s and maybe some of the smaller HX50s. HE500s are the biggest variety, as they not only cover all the HX5* range, but HX60s too, which are beasts!
But while names mean less than ever, the turbos are better than ever, and the HE series are all as good as the HXs, or better. Good times!
The Holset HE221W is probably the first of the HE turbos to become known in the tuning scene, and not surprising too, as it’s one of the best T2 flange turbos out there, a hugely efficient turbo for its size.
A replacement for the HX27 with newer (and slightly bigger) wheel designs, it’s proven capable of up to about 380bhp but fast spool even on sub-1.6ltr engines; in fact I’ve seen them used as twin turbos on a 700bhp 2JZ- It’s a great little turbo. It spools like a little TD04, with 7psi+ by 2500rpm or less on a 2ltr engine, but unlike most small turbos, is still efficient at big boost- It’s still on the compressor map at 3bar!
Even on a 2ltr Cosworth rally car using the tiny 34mm rally inlet restrictor that slows spool and reduces boost, it was capable of hitting full boost 750rpm faster than the original Garrett T3 (which is also capable of far less peak power). Not only that, but the engine made well over 400lb/ft at just 25psi boost, way more than other turbos make at the same boost, showing how efficient they are.
Common myth was they all had billet wheels, but that’s just not true, and the cast wheel versions are to all intents and purposes just as good. Usually has a 7cm turbine housing.
The HE211W is a slightly smaller version, the compressor map shows it’s capable of 32lb/min, ie about 320bhp, and seen them hit 25psi by 3000rpm and less even on a little 1.6ltr diesel. Most the ones I’ve seen have a 5cm turbine housing.
The HE200, well that’s generally one of the two above specs, usually are 211 spec, but could be either. Often the 211 version doesn’t have an anti-surge inlet, the 221 always does, but even that isn’t a sure way to tell, as the smaller ones do sometimes- I’ve owned anti-surge billet HE200s which had the 211 size wheels. They can come with billet or cast compressor wheels, and unlike the 221/211, don’t always come T2 flange; sometimes they’re all kinds of odd shapes!
There’s also a VGT version of these, which looks very promising for small capacity TDIs, but I’ve never used one personally.
Here's a HE221W compressor map and some data from a HE221W on a 34mm restrictor Cosworth rally engine.
Lots of HE221W 6cm for sale HERE
Here's a HE211W compressr map and a dyno graph from a old VW 1.6ltr turbo diesel in a Mk1 Golf running a HE211W...
One of the rarest, but if/when they get more popular, from the one I’ve seen at least, one of the best. These come in various specs, and are a middle ground that seems to replace the HX30, which no longer really has a purpose when the smaller HE221 can make more power! I’ve only personally owned one, and it was 11cm T3 twin scroll with compressor wheel specs I’d say were good for around 450-500bhp but with very fast spool. Quite like a HX32 or HY35, but far more compact, no bigger than HX30 size, but far more capable.
Others I’ve heard of certainly had smaller compressors, but still seemed like 400bhp+ capable turbos. One for the future I think!
This covers everything from (I think?) HX30 equivalent units, and certainly HX32/HY35 equivalents (Sometimes known HE341, but some 341s are purely HX35 wheel size), and HX35/40 hybrid equivalents (Sometimes known as HE351), but mostly they are the ever popular HX35 size. I’ve yet to see anything drastically different in wheel design from the HX versions, though slightly more often billet compressor than the HX versions were, but as the HX/HY3* series were generally the most popular ones for most tuners, the HE3** no doubt will be too.
There are VGT versions of the above, the ones with V/VG/VE at the end, and as ever, they’re a similar design, just a VGT turbine housing. Generally the VEs perform to the same peak power levels as the non VGT versions, but they spool much sooner, up to 1500rpm sooner.
As with the others, these come in conventional and VGT form, and cover what was HX50s, HX52s, HX55s, and HX60s. Most commonly I’ve seen HX55 equivalent ones, all so far with billet wheels, and some with totally different compressor wheel designs than usual, like a modern turbofan aeroplane engine with heavily curved blades. I’ve seen one, just labelled as HE500 as most are, which had an absolutely huge billet HX60 sized compressor wheel and housing (far bigger than HX55 comp housings, and they’re huge!), but a much smaller HX55 turbine housing and wheel.
Yet to see one in the flesh, but basically it’s the artist formally known as HX80/HX82. Big! The one below has a billet wheel and what is a fucking TINY housing for such a big turbo, just 22cm! Could be amazing if you can find one in the right spec...
H/HC/HT and ‘other/classic’ Holsets
There are a LOT of older Holset turbos out there, right back to things from the 1970s that look like antiques, and most of them are zero use to you.
I’m no expert on these as they’re old-skool and I tend to stick to the HXs and HEs, but I know a bit about some of them that are a little use to some of you.
HTs are reverse rotation turbos, ie spin the other way, and I’m not really sure if they’re meant to be the equivalent of the HX series or the older HC series, but I know they’re not meant to be quite as capable for their size as the HX series.
Probably the most use to tuned car owners, mostly as they’re still seen fairly often, are the H1 turbos. H1Cs are very similar in spec and performance to the HX35, with the ‘big’ H1C in particular being basically a HX35, but even the ‘small’ version (smaller compressor wheel) is meant to be good for well over 400bhp.
The H1E is like an older version of the HX40, and again comes in varying wheel sizes. The small version isn’t great as it has pretty much a HX35 sized compressor, but the ‘big’ H1Es are practically HX40s in all but name.
The turbine housings on the H1C is a direct swap for HX35s, and the H1E for HX40 ones.
The others I’m not going to bother going in to as I don’t know enough about them and you’ll rarely see any other good ones suitable for anything other than maybe tractor pull stuff to be honest!
If you just want to smoke your tyres, do skids, burnouts, and powerslides, fuck yeah, have all the power you want and forget the rest, and that can be a whole lot of fun in a RWD car, mega fun.
But massive wheelspin in a FWD is pretty much super gay and not fun at all, and with 4wd your car is either insanely powerful or something's set up very wrong.
Fact is, if you want to actually go fast, it's about way more than just power, and a lot of people don't seem to be able to grasp that fact.
I'm not on about handling and stopping either, that's a whole different subject, I'm purely on about getting this power to the ground- Traction!
You see a lot of people, a hell of a lot of people unfortunately, really chuffed with their car, saying how 'fast' they are, as they smoke the tyres in 4th or whatever just by going full throttle.
But, err, if your car is wheelspinning, it's not going to be that fast until that stops, and in a lot of cases cars with half the power but decent traction will be leaving you for dead.
I'm not sure if these people truly believe their car is quick and have never actually raced or timed it to realise that their wheelspinning mess is actually nothing special, but practically everyone with a tractionless mess act like their cars are rapid when they're not.
One of the most common things you see is people really proud that their engine spools fast and smokes the tyres constantly, while also slating cars with with similar power but far less torque and low down power (due to bigger or no turbos, less capacity, more rpm, etc) as 'dogs' at lower rpm just because they haven't got a ton of torque.
But the fact is, thanks to the more sensible/usable torque levels they have for the amount of grip they have, these 'dogs' are often far faster in reality.
FWD and tuned diesel owners are worst for this, but grip affects almost everyone with big power on road tyres.
The bullshit talked about grip, or lack of, works the other way too, as the people constantly say FWD cars are useless with more than 200bhp/250bhp/300bhp (depends who you're talking to) are wrong as well.
Yes FWD is useless even at 200bhp with tons of torque, shit tyres, and an open diff, but even with 500bhp+ I've experienced road legal FWD cars that put all the power down from 2nd gear on, and with rear wheel drive cars you've got even less excuse to have no grip. Fuck, if you've got 4wd and big traction issues then you either need to sort your shit out or something is broke.
So yeah, having no traction means your is gonna accelerate slow no matter how powerful your engine is, and here's the various ways to help fix that...
The number one way to improve your traction is tyres. And as blatantly obvious as that is, people still ignore it, and I'd say there's far more big power cars on skinny normal road tyres wheelspinning everywhere, than ones running decent tyres and actually going fast.
The difference in traction under acceleration between the same size tyre, one a normal but decent brand road tyre, and one a road legal semi-slick, is massive.
I've experienced, many times, cars go from wheelspin in 4th with good 'normal' tyres to full traction most the time even in 2nd with a set of semi slicks of the same size.
This, providing there's no standing water, is actually the same in the wet too; it's only standing water when semi-slicks can be a bit crap.
People's reason/excuses for not running decent tyres like this is always stupid too; either that they're rubbish in the wet, which I don't really agree with anyhow, or that they don't last long, which is a false economy when they instead have a powerful car that's a complete waste of time and not actually very fast as it has no grip.
Tyre size is another big one- People rarely even fit the widest tyre they can get under their standard arches, never mind go as far as modify their arches to fit wider ones for decent traction.
This is also usually ridiculous as they end up spending ten times the money doing that will cost on other pointless upgrades. In fact it's that daft that people will fit the biggest wheels they can fit under the arches as they think it looks cool, but then fit way skinnier tyres just to help wheel fitment! You can't have it all, and what do you want? People to think your car looks cool, or for it to be as fast as you tell everyone it is?
Finally, tyre pressure- It can make a big difference to traction, and as long as your car isn't hugely heavy you can often run lower than the typical 30-35psi most people have theirs set at.
It's certainly worth looking at, especially as it's pretty much a free mod, and in drag use people often run barely 10psi depending on car and tyre type, and while this has an adverse effect on handling, on some lightweight cars some people still run under 20psi on the road and circuit, so it's worth some experimentation to see what suits you.
So many “Oh my God my car is soooo fast, my wheels are spinning in 9th gear” type people are wrong. Only one of their wheels are spinning, and their car isn't fast at all, as it's got an open diff or a really crap factory LSD.
Just like decent tyres, the massive difference a decent LSD makes to traction over an open diff is hard to imagine unless you experience it. It really is night and day, and in my book worth every penny. A hard used performance car with an open diff, even a pretty low power one, is not for me; I hate it.
There are lots of performance advantages of a decent LSD, but we're talking about getting your engines power down in this feature, and that's where a limited slip diff really is most obviously felt.
With an open diff power just goes to the wheel with the least grip, which means one wheel quite easily spins up while the other has no power going to it all, and the end result of that is no forward movement and just pretty much sitting there spinning one wheel like a dick.
With a decent LSD, power is forced to both wheels regardless of what has the most grip, which not only of course massively increases traction for that reason, but even WHEN the wheels are spinning, especially with a plate-style LSD, as both still have the power going to them rather than just one, there's still a lot more traction and therefore forward movement even when wheelspinning.
It's hard to imagine unless you've experienced it, but the amount of acceleration even when wheelspinning hard when you've got a good aftermarket limited slip (or locked/weldeds/spool) diff can be pretty incredible on some cars.
Please bear in mind though I saw a 'GOOD' LSD, as quite a few factory LSDs are barely better than being an open diff, especially once they get older, so don't just think because your car has a LSD as standard that it's effective- Often far from it!
YOUR SUSPENSION GEOMETRY
When it comes to getting power down, maximising tyre contact patch is key to making the most of what you have.
The most obvious factor here is to minimise camber on your driven wheels, BUT if you're really serious about putting the power to the floor it gets a bit more complex than that.
Most suspension designs have dynamic camber change, ie when your suspension lifts or squats, the camber angle changes. Some suspension designs change more drastically than others, so exactly how much you need to cater for this depends on your cars own setup, I can't advise you on exact numbers, but if you're serious about traction, you got to take this in to account.
Upon acceleration, a cars front end naturally lifts, generally reducing the camber angle of the front tyres, and the rear end squats, increasing the camber angle of the rear tyres. Because of this, on FWD cars a small amount of negative camber is often no bad thing as it can turn to zero camber as the front lifts slightly, and on RWD cars, zero camber, or even some positive camber, is often used on cars looking for maximum straight line grip, as this counteracts the natural negative camber increase that happens as the back end squats.
YOUR WEIGHT DISTRIBUTION
As mentioned in the geometry bit, when accelerating, the front lifts and the rear squats, and of course, you want to have as much weight over your driven wheels as possible, so why not do something about that?
Thanks to the rear end naturally squatting, RWD cars have it easier when it comes to grip, as the whole car is pushing down on the driven wheels, but regardless of this fact, moving any weight you have to the rear end is never a bad thing to help maximise acceleration grip; unless your car has so much rear end grip it instead does huge wheelies and tries to flip over that is...
On FWD cars the weight distribution issue can be much more important. The front end of a car naturally goes light upon acceleration, which is the last thing you want when it comes to grip, so anything you can do to keep weight over the front wheels the better.
Obviously this is no easy task, as you're limited to what you can fit under the bonnet, but this is why many FWD drag cars fit the fuel cell up front, and some people have even tilted the engine forward a little to help with the weight distribution.
Weight distribution is more than front and rear though- It's left to right, and this can have a major effect on traction due to how much force is put on each tyre. I've seen cars get major improvements in traction my making the corner weights over each driven wheel to be as equal as possible, therefore equalising their grip; to the extent some have said it was more effective than when they changed from an open diff to a LSD!
This is something which can be done by physically moving parts around the car, as well as small changes to ride height if you have coilovers. To even remotely accurately do this you need a set of corner weights, but this is something many tuning shops have and are more than happy to do for you.
While in general adding weight is never ideal, if traction is your main goal and you're still struggling with other methods, adding weight to the very front of a FWD car via thick metal undertrays or weights behind the front bumper, or to the very rear of a RWD car, either with weights behind the rear bumper or added to the boot, is sometimes done to push the driven tyres as hard in to the road/track surface as possible.
Finally, weight transfer from suspension movement. As I've explained, you need to keep the weight on the driven wheels as much as you can, and that generally means allowing a RWD car to squat the rear and lift the front, and conversely trying to prevent a FWD cars front end from lifting and the rear from squatting.
For FWD cars this tends to mean stiff rear suspension to help prevent squat, and various clever ways to prevent front suspension lift (which unfortunately depend on your stock suspension design, so I can't list them all here).
While jacked up rear ends are also sometimes popular, most the fastest FWD people tend to agree it's no big benefit, if at all.
For RWD cars they tend to want to allow the front to lift without lifting the wheels clean off the ground, and allowing the rear end to squat. A fairly soft rear end is a clear start point, and on the front things like soft and relatively long travel suspension, often with no anti-roll bar, allows the front end to naturally lift but also can help prevent the car lifting its wheels, which, while looking cool as hell, gives you zero steering, and potentially massive problems when you come back down to earth!
LIMITING YOUR TORQUE LEVELS
Last, but DEFFO not least, I'm going to talk like torque is a bad thing. As sometimes it is!
This is probably the most ignored factor when it comes to traction, as who'd want to willingly give up performance? Only a mad man, surely?
Well there's two things here. Despite the myth diesel and V8 owners like to loudly shout at every opportunity, torque doesn't really win races, and if you're spinning you ain't winning, so you're better off having less torque, so less wheelspin, but more acceleration.
This tactic is common on modern turbocharged drag and track cars, and is part of the reason so many are so fast and controllable in recent years, with things such as boost by gear (ie lower boost in lower gears), boost by speed (similar to boost by gear but works it out with speed) and boost by rpm (ie mapped to the boost rises slower and more progressively than they naturally could, to prevent a big spike of boost spinning the wheels), all easily configurable on a good ECU, as well as clever traction control systems that can limit wheelspin by slightly lowering torque when wheelspin is sensed without killing the power and slowing the car down like many factory systems.
The thing is though, while you may think these are pretty hi-tech and extreme tuning methods, this is actually way more normal and common than you many think. Many factory turbo cars, even some that are 25 years or more old, come with boost by gear or rpm as standard. Yes, many cars have it set, from the factory, that their boost pressure is lower in lower gears and/or rpm to reduce wheelspin, all controlled via the ECU and factory boost solenoid.
Even without clever ECU tricks like boost by gear or other traction control methods, a good engine spec and a good mapper can massively improve traction simply by creating an engine with a good power delivery.
Huge torque, or just sudden increases in torque, when you've not got the grip to use the aforementioned, is pointless and will prevent you reaching your performance goals, but are easily avoided.
A big part of the reason Prochargers and Rotrex units (ie centrifugal superchargers) are so popular among V8 drag racers and FWD track cars, is because of the linear power delivery they give, with no huge torque spikes to spin the wheels, and a very progressive increase in power all the way to the rev limiter, making for a tractable, controllable, and predictable car with massive peak power levels but far less wheespin than a typical car of the same power equipped with a positive displacement supercharger, nitrous, or a typical turbocharged setup, purely as they tend to give huge and peaky torque curves.
Other engine spec changes can help this too on traction-limited cars. Increased capacity rarely increases peak power, but certainly increases torque, so should be avoided if you're already struggling for grip. Small turbos at high boost means big torque and eaiser to drive, but a bigger turbo at lower boost for the same power can often give a better power delivery for a grip limited car, which is also kinder on the engine too. Using rpm to make power means less torque needed for any given power level, which again can actually be a useful thing if you're struggling for grip.
And that's it for now folks! Hope you've enjoyed this feature and found it useful, and of course show anyone else you know who may get a use out of it too.
I've actually got about 10 other features in progress right now, just, thanks to life getting in the way (I have some very kind Patreon donators, but the total is still very low so I certainly don't make a living doing this, or even close!), I've just not finished the others yet, but I do these at any opportunity I can, so please, watch this space!
Since the death of car magazines and internet forums, and the rise of YouTube videos and Facebook groups, the amount of misinformation and pure bullshit about tuning is higher than ever. It's fucking unreal what gets said and how often, and it's making me a bit disillusioned with the whole scene, but it's also made me want to clear a few things up lately, as reading pure shit constantly is doing my head in.
Probably the worst piles of bullshit I hear is about turbos, so let's clear some stuff up in ten very important points.
Apologies for the swearing and less than sexy layout of this feature, but this is me saying what I think and explaining some stuff rather than trying to look impressive...
No1- IF YOU'VE NO EXPERIENCE ON THE SUBJECT, PLEASE, SHUT THE FUCK UP
This is the worst thing of all, not just on turbos, but everything. Seems most the people who shout the loudest with their advice are the people who know the least.
On a certain car group I'm a member of that's mostly turbo related, the two main people who reply to peoples questions seem to have zero experience and reply with complete and utter shite almost all the time, but comment so often and so confidently, to anyone who didn't know who they were, ie most people, they'd sound like people who know what they're on about.
Shit like this, on Facebook, on YouTube, and in magazines, is what's killing the scene for me most of all.
Unfortunately a lot of tuners these days will give iffy advice too, either to suit their agendas and sales, or because they're clueless on that exact subject but won't ever admit to it as they have to be seen as the all seeing gods of tuning to their customers. Fucking minefield out there.
No2- TURBO SIZING ISN'T THAT HARD-
One of the most common things I see is people (never with any experience of the turbo/engine/anything) going "OH EM GEE, THAT TURBO WILL NEVER SPOOOOL" just because it's not a fucking tiny little turbo, even if the engine is pretty big.
Don't just guess if something will spool. Either go from your past experiences or do a bit of Googling for proven results and you can make a VERY educated guess by looking at other cars and engines and turbos, even if neither are exactly what you're using.
Unless you're using a horribly specced mismatch of a turbo, or some ancient piece of shit, both of which are very rare these days in all honesty, turbos of a similar size/spec all spool similarly enough or any given size to make a very good guess on how it will work.
Wondering how a 900bhp turbo will spool on a 4ltr for example? Well about the same as a 450bhp turbo does on a 2ltr. Simple. It's not that hard. (THIS is one I see loads of with Toyota 1UZ engines- You can spool a fucking HX55 on one EASILY, but people fit turbos more suited to engines almost half the size, and wonder why they make crap power!).
Wondering how much faster a twin scroll turbo setup of any given size spools vs a single scroll one that's otherwise pretty much the same? Roughly 600-1000rpm faster in general. 2Ltr single scroll setups with ~600bhp capable turbos like GT35s and HX35s are full boost by around 4500rpm typically (seen 5000+ on GT35s with wild cams and the biggest housing though- Shite!), and proven as low as 3500rpm with a good twin scroll setup and 12cm HX35s for example.
No3- BALL BEARING TURBOS DON'T MAKE VERY MUCH DIFFERENCE TO SPOOL-
Fact. Despite being one of the most common myths. I've even posted a video of the owner of Xona Rotor saying the same thing, and he sells the fuckers. It's a mix of sales speak and bullshit that says it makes a big difference.
A Holset HX35, a Garrett GT35, and whatever other similar 600bhp turbo with similar size turbine wheels and housings spool about the same IF all else is equal. This is fact, no matter how many times pricks say one is "An old diesel truck turbo" and one is some kind of superduper thing. It's bollocks.
In theory it helps, and it does, but by a really small amount, an amount you often can’t even feel. Wheel design, housing design, manifold design, exhaust design, cam spec, mapping, ALL SORTS, all make a way way bigger difference, ie a really noticeable difference, vs it being BB or not.
The REAL advantage of BB turbos is they can take higher thrust loads for better reliability in extreme use. Though that's all relative to how good/bad the non-BB version would be of course- My friends GTX2860R Gen2 has massive thrust (ie in out) play and it's only done a few thousand road and dyno miles, albeit at 33psi boost.
No4- JUST BECAUSE THE TURBO IS CAPABLE OF A CERTAIN POWER DON'T MEAN YOU WILL MAKE THAT POWER...
Lots of people think this, and it ain't gonna happen. This isn't just the case with running a turbo at very low boost, but most commonly people buying, say, a 600bhp turbo, running 1.4bar or some medium amount of boost, then wondering why they've not got 600bhp (Hint- Most the time you'll be at more like 2bar or more to truly max a turbo out unless it's a very small turbo for the engine size).
These days this issue is coming about thanks too all these tiny but very flashy turbos with funky compressor wheels rated at big power but still running teeny tiny turbine wheels and housings (ie a huge mis-match for most engines, and more sutied to twins on insane power GTRs etc). Things like the smaller Garrett GTXs and so on are big ones for this, as they might be rated at whatever power, but they're not gonna do that aside from on a pretty tiny engine, or as twin turbos on a medium size engine (Such as twins on a Nissan GT-R V6 or Toyota V8), as they've not got the turbine flow to max out on larger capacity engines. Ever notice the truly powerful engines have actual big turbos with big turbines? Yes, that’s because you need it.
What goes in has to come out of an engine, and while better designed wheels help, size is still king.
Take the Garrett GTX2871R rated at 560bhp, or even the new G25-660 turbo rated at 660bhp. They both have tiny 54mm turbine wheels, smaller than a stock little CT12B off a 1JZ VVTi. I don't care how fancy a turbine wheel is, with that size, you're either not going to max out one of them on anything but sub-2ltr engine at mega boost, or your pre-turbine backpressure will be astronomical.
You'd not make even half of many of these turbos rated power if you was daft enough to fit one to a larger engine, as it's as much about turbine flow as compressor.
Even looking at Garrett's own turbine maps shows it's no magic- The GTX2871R turbine with the biggest housing flows about 21lb/min, the G25-660 one with the biggest housing flow about 24lb/min. Both less than a GT30R turbine does with the biggest housing at 26lb/min, despite the GT30R rated at a good 100bhp less.
So even IF you make the power, you'll be making it with a far less happy/healthy/reliable engine than if you did with a bigger or 'older' turbo that had a bigger turbine wheel.
No5- TURBINE SIZE IS KEY-
While little turbine wheels and housings help spool, and are fine on suitably small engines, what goes in has to come out, and the smaller the turbine wheel and/or housing, the less can come out, which means less power per psi boost, and less engine reliability.
When chosen right, this is just a trade-off, you just give up a bit of power for a bit of spool, with no reliability issues, and still ballpark correct power.
In fact if going for the maximum power and torque but fastest possible spool, you can build an engine like they would a rallycross engine, that's been specced to handle big boost and big backpressure from a relatively small turbine side with no issues and be loving life. Unfortunately most engines aren't specced like that.
But more often than not these days, people think running the tiniest housings and wheels they can find for any turbo they think can do the power they're after is the right thing to do with no bad consequences, as they have zero understanding that turbine flow matters. Because of this the result is often way too small, so they often struggle to make the power they do, and even more often have reliability issues due to the massive pre-turbine backpressure.
Pre-turbine backpressure is the no1 killer of turbo engines (behind shit mappers!), and both killers are pretty invisible to most, and other stuff gets blamed for the problems.
The less turbine flow you have, the harder time your engine has to stay alive. Heat issues and far less resistance to det, are the biggest problems, problems which people tend to first realise when they're shitting out head gaskets and pistons a lot, or needing to run race fuel when other similar engines with bigger turbines don't...
There's plenty of examples where there's two similar engines, running similar power, but one is highly strung and less reliable than the other, just as it runs a smaller turbine side in an attempt to get faster spool.
Unless you've specced the engine to suit, it's simply not worth trying to gain a tiny bit of spool considering what you give up just to get that.
And remember the basics- The bigger the capacity, the bigger the turbine flow needs to be for any given power. What will make 600bhp on a 1.8ltr might have a turbine side too small to even make 400 on a 3ltr...
No6- LAG VS BOOST THRESHOLD-
What most people call 'Lag' isn't lag, it's just not being in the boost threshold.
The rpm where your turbo can't make boost, that's being out the boost threshold.
Lag is your turbo response when within the boost threshold.
You put your foot down at 2000rpm and it don't come on full boost until 4000rpm isn't lag, that's being out the boost threshold.
You put your foot down at 4000rpm and any delay then is LAG.
But how much 'lag' is there on even slightly modern turbos when truly within the boost threshold? Even fucking big ones? Some vs being naturally aspirated, but in real world terms, very little, not enough to win or lose a race unless you're rallying.
Even something like a Holset HX35 on a 2ltr with a single scroll manifold (Bad idea btw when twin scroll often spools it 1000rpm faster). Boost threshold would be fairly high, full boost not until 4.5k, but do you think there's any real delay between planting your foot to the floor and fucking off down the road like a rocket when you're within the boost threshold (ie 4.5k+)? No. Pretty much zero, even for things like drifting etc.
No7- BOOST = TORQUE.
If you're grip limited or haven't got the strongest engine or transmission out there, torque can do more harm than good, BUT if that's not an issue, torque is always fun! Despite this, a lot of people seem to be confused why they haven't got lots of it despite having lots of power.
The answer is mostly boost. The biggest thing to make high torque numbers is boost pressure, and many cars, especially at 1bar or less, even the smallest fastest spooling turbos, can feel almost like a powerful N/A engine with most the power up top and fairly low torque, but the identical engine with another half a bar of boost can feel like a totally different engine with ridiculous amounts of low and midrange torque.
The lower the rpm you can make boost, the bigger the torque numbers tend to be for any given boost level, but the more low down torque you have, the harder it tends to be on engine internals, especially conrods, so it's a double edged sword in some ways!
Good example of boost giving torque and transforming how and engine feels was the old 13B rotary in my RX7. It was a large street port engine running a fairly small HKS T04E. At 0.8bar, despite being full boost by 3000rpm, wasn't really "fast" until at least 5.5k when the ports really came in to their own, then it screamed up to 8k; feeling much like a tuned N/A engine. At 1.5bar though, despite peak power not feeling much different up at 8k, it was a rocket ship with a ton of torque right from 3k to the limiter now. It was tons more fun at 1.5bar and easier to drive faster, but if I didn't have the massive grip to cope with it, it would've been slower to be honest, but still, more fun...!
I like boost!
No8- LEARN TO CHANGE FUCKING GEAR-
Unless you've made a tragic and totally mismatched engine or gearing setup, there is pretty much zero excuse to be caught off boost unless you have no idea how to fucking drive and change gear.
Putting your foot down at low rpm then blaming the turbo for you not going fast is fucking lame. No, it's your fault for being at low rpm. Your fucking fault. Even if you got a tiny turbo, you'd be going a lot faster if you had the sense to be at a higher rpm.
Even if you got a standard turbo on a petrol car that is on boost by 2500rpm, you'd accelerate a lot faster if you made sure you was in the right gear so you was already at 5k+. I've got an Impreza at the moment, 2ltr, and a tiny little TD04 that even 1.6s spool easiy. Yes it spools at low rpm, but to do fast I'd still drop a gear or two from cruising rpm so I'm at at least 5k to accelerate as hard as I can, as I'm not stupid.
You could have a GT25 or a GT35 on your 2ltr, and while the GT25 will be faster at 3k, it will still be slow, and but would be FAR faster at 5k. But the GT35 will be FAR faster at 5k regardless.
God help you if you drive a highly strung N/A engine- Any engine even approaching 100bhp per litre, even with fancy variable valve timing to help low down power, the real powerband starts at at least 6000rpm on non-turbo lumps, and by then even fucking massive turbos are at full boost.
You ever wonder why so many 'fast' cars look so average when the owners give them some beans? It's because people are fucking useless and don't understand how to change gear, that's why! Most owners are a waste of a good car...
No9- WHAT YOU GIVE UP LOW DOWN, YOU USUALLY GAIN UP TOP, SOMETIMES MORE! -
People fucking obsess over low rpm performance, and think a bigger turbo gives a smaller powerband, so would don't want to run one as they think it won't have a decent power band, but on modern engines, that actually rev, this is usually bollocks, and it's often the opposite.
Most modern turbo engines safely rev to around 7500rpm, some 1000rpm more, and even the lowest safe revvers these days are no more than 1000rpm less.
But, despite this, most modern turbo engines make peak power at least 1000rpm lower than their safe rev limit, so there's room for more if you can make it worth it...
A typical fairly small turbo engine making like 150bhp per litre, so a 300bhp 2ltr etc, makes good power from 3000-3500rpm and peaks out 6000-6500rpm. So you've usually got a 3000-3500rpm power band.
A typical bigger turbo engine, say 250bhp per litre, so a 500bhp 2ltr etc, makes good power from about 4000rpm, but tends to pull hard with no let up until 7500-8000rpm. So you've got a 3500-4000rpm power band, ie the same or fucking BIGGER, not smaller.
Even if you only pulled hard to 7k, and in all honesty you've probably done something badly to have an engine that spools that late but dies out that soon, you've still got the same size powerband as a smaller turbo, just higher in the rev range, and you also happen to have 100-200bhp more!
You can make a fucking mess of things, with small downpipes, shit manifolds, badly matched turbos, stupid cam specs, and so on, and make a powerband smaller than it needs to be, but these days you'd have to fuck things up good and proper to make a powerband much smaller with a larger turbo unless you go to a REALLY fucking big turbo.
If things are specced and built right, you can have a fucking big powerband. Even with some 600-650bhp turbos, on 2ltr engines, with good overall specs, good twin scroll setups etc, you see cars making big power from 3500rpm all the way to 8000rpm, that's a massive power band, way bigger than any factory turbo engine, but while also having about TWICE the bhp per litre of even the hottest factory turbo engines these days.
This sort of shit is especially good on Honda engines that love a good rev. When N/A they don't really come alive until 6k+, but rev to 8k+, but provided you can drive you still won't ever fall out the power band. Even a fucking gigantic turbo is on full boost by time the N/A car is in the powerband anyhow, so even with insane, really fucking insane power, with a huge turbo, you'll still have a bigger powerband than stock...
No10- YOU DON'T 'GET WHAT YOU PAY FOR'
Turbos are all kinds of prices, from sub £200 eBay specials to £2000 swanky ones, and everything in between. But is a £2000 ten times better than a £200 one? Or even a £1000 twice as good as a £500 one? Personally, I'd say no.
Cheapy eBay ones, well that's where it's real a gamble. Personally I think a lot of these under-perform as the typical type of person that runs one is a clueless cheapskate so the car is an unreliable underperforming piece of shit in general due to the mistakes and lack of care/knowledge from the owner, rather than the turbo being truly shite, but still, it's a gamble and not one I've ever made personally yet.
Another thing you see for a couple hundred quid, is used and sometimes new turbos off trucks and so on. This is FINE if you know exactly what the fuck you looking at, but most people don't. People see "HX35" or "GT40" or "T4" and think it will be ideal for them, not realising there's a 1000 variations of almost every turbo type on the planet, and 90% of them are not suitable for you.
The vast majority of turbos, even ones on some of the more powerful tuned engines on the planet, are actually commercial/diesel based, but that sure as shit don't make them all suitable! Most big OEM commercial/diesel turbos will have far too big a turbine housing to be much good for the fairly small engines we tune, so a random purchase just because it's called a HX35 or whatever could well be a total waste of money unless you know what you're buying.
For somewhere between 400 and 600 you can often get brand new GOOD/CORRECT spec Holset or BorgWarner turbos from a specialist who knows about these turbos. Personally, for my budget and needs, this is what I go for, and what I feel is the best value for money.
Are they the very best turbos on the planet? No, of course not, if money was no object I'd have some swanky as fuck £1500 Precision or GTX or EFR or whatever. But for 99% of us money is an object, and from experience, comparable size for size on wheels and housings, both either twin or single scroll, the performance difference between a decent Holset or Borg and a swanky one for 2 to 3 times the price, is pretty minimal.
More importantly however, and the money saved on the turbo can be spent elsewhere (better manifolds, exhaust, cams, mapping, whatever) to make the performance better than any turbo alone will.
If you have the cash to make everything on the car perfect, and can afford spending big bucks possibly yearly when you need to replace a broken turbo, fuck yeah I'd get the expensive one as it's a little bit better, but spending loads on a turbo but then having pretty average/crap spec other bits as you've not got the budget for it all, is fucking stupid IMO.
And now, top dollar turbos. Yes, they are the best, defo, but they're also expensive to buy and fix, often most of the cost of buying a new one, so you need to be able to afford it short and long term. Top dollar turbos tend to not be no more reliable, arguably less sometimes- What you're paying for is performance rather than longevity, so make sure you can afford the upkeep.
A good example of a lot of the things I've talked about in this feature was the RB20 engine build I did in my R32 Skyline.
Back when I did that everyone said RB20s were shit, unreliable, didn't spool turbos, even shitty little ones that barely make 300bhp, didn't make power, etc etc.
Anyhow, long story short, this good choice of parts, good choice of what to spend my fairly low budget on, and good turbo sizing, made for a RB20 that was making positive boost by under 3000rpm, full boost by 4000rpm, pulled hard to 8000rpm limiter, and made 470bhp at just 1.5bar on pump fuel, and would've easily made 550 with more boost- Which it was capable of with no det, if only I didn't have shit coils at the time of mapping that missed occasionally above 1.5 (we tried at up to 2bar). Totally reliable even with years and years of hard use too.
So faster spool, more power, wider powerband, and more reliable, than 99% of RB20s, especially back then, with 3 times the budget and running flashy turbos, and the difference was simply buying/picking/making the right bits.
If I'd have had the budget for even flashier turbos and stuff it would've been even better, but this shows you better off with a correct overall spec than the usual totally random guesswork spec with a 1500quid turbo bolted to it like most.
Here's a YouTube video on the whole build if you give a shit...
So yeah, I think that covers most the typical turbo bullshit I keep reading and seeing on YouTube. Hope you liked it, make sure everyone you know in to tuning sees this too, and hopefully some bullshit might stop getting said so often.
Plenty more things people should shut the fuck up about, so there may be more of these soon...
You can't read anything, from Wikipedia to 'respected' car publications without them mentioning the “fact” that the insane Porsche 917/30 CanAm cars had '1580bhp' or '1580bhp in qualifying trim' or similar. But personally, I don't think that's true at all.
The 5.4ltr twin turbo engine was INSANELY fast, zero doubt there, and the claims of 1000bhp+ in qualifying trim I certainly do believe. The fact the car weighed under 900kg was also was a big part of why the cars were really mind blowingly quick- Especially bearing in mind this was 1973, long before most of us were even born!
BUT do I think the CanAm versions ever made this so called 1580bhp so many quote these days? No.
I think this is yet another case of half-truths from a long lost past getting mixed up, and now being talked about like reality. And after speaking to others who are some of the few people that I do trust what they say when it comes to things like this, they agree.
But ONE 917/30 DID run at this power, I’m 100% sure of that, but never in CanAm!
The CanAm series was cancelled after a season of the 917/30 obliterating the opposition, leaving some incredible cars with no series to race in, so Porsche decided to use it to go for the world speed record for a closed circuit, at Talladega Speedway.
6 months of development later, and the car had one big change that made it unlike all the other 917s- It now had INTERCOOLERS.
Look at all other pics of the Porsche 917/30s, old pics or even the cars today- They didn't run intercoolers at all! Pure hot air.
BUT for this speed record attempt they wanted more power and performance than ever before, and a big part of that came from two large alloy intercoolers at the rear of the car...
THIS is where this '1580bhp' story comes from IMO. But the CanAm race cars? With no intercooling at all? No, they wasn't as powerful as this, even in qualifying. Hundreds of bhp less in fact, same as comparing any engine at significant boost levels with and without intercooling.
For what it's worth, the car did brake the record, averaging over 221mph through the whole lap, going well over 230mph at times, and that's STILL a record at Talladega to this very day.
So yeah, next time you see or read about 917/30 CanAm cars having a supposed 1580bhp, well, you know a bit more about the reality of it now.
Here's a couple more pics of the intercoolers on this one-off spec car for you too...
A fairly short one this time, but a good bit of mythbusting and something very cool most of you have probably never seen.
Hope you enjoyed this one, and as ever, stay tuned with more coming on here, the Facebook Page, and the YouTube channel.
And please, if you enjoy what you see and want this to carry on and hopefully grow, please become a Patron of StavTech and receive exclusive bonuses for doing so too!
You may think the title of this feature is a big claim, but I'd say it's fact, and in fact this car is FAR crazier than what 99% of people who know this car even think it is!
As you may have seen on THIS recent post on the Stav-Tech Facebook page, I personally think, especially from an engine tuning point of view, 80s and early 90s Rallycross is THE most insane motorsport there ever has been, even more than Group B rallying.
BUT the thing is, it's all pretty unknown to most current tuning fans, and there's VERY little detail out there that explains how crazy the cars were- Even most retro rallycross fans know very little about the cars back then. I've asked these 'fans' many times what engines were in certain cars etc, nothing complex, but people rarely even know that much!
I’m sure that if only people today realised how insane these cars were, they'd be more legendary than even Group B cars are, and I'm determined to find out the details for YOU guys.
While they're pretty unknown to most, their specs and their performance are exactly the kinds of things you love, and totally relevant to your own tuned cars of today.
Anyhow, the first car I've managed to source the long-lost info of is a car that's always been my favourite rallycross car, despite even myself not knowing that much detail about it, and it's this- Arild Martinsen's E30 BMW M3...
I'm not a massive E30 M3 fan normally if I'm honest. I've driven a few, standard and modified, and while I think they're cool cars, they've never been a car I've wanted to own, but this one, well shit the bed, this one is literally my DREAM CAR.
Well why? Well, before I give you all the details, I'll let this absolutely incredible video (From 30 years ago!) below do the talking, check it out...
Watched it yet? Did you say "Holy shit!" and "Fuck me!" loads of times while seeing that 700bhp four wheel drive E30 M3 fly around the track, sideways everywhere, accelerating like a rocket, and chucking flames out the side exit exhaust? Well yes, that's the pretty normal reaction, as that thing is flippin' bonkers.
Funnily enough though, that's one of the VERY few videos out there of this car, as it actually wasn't hugely successful in rallycross, as while it was insanely fast and generally awesome, it just didn't have the traction to match. But it's performances have made it a favourite with many to this day- Including me!
The thing is though, that video is pretty much as far as most people's knowledge of this car goes, and it was only relatively recently I'd even seen an engine bay pic of the thing myself.
But as I love the thing, and I knew you lot would too, I decided to do some serious research (Not just Googling, as there's fook all on the net about it- Believe me, I've looked!), which has enabled me to do this feature you're checking out right now.
Starting with the engine under the lightweight Kevlar bonnet, the common story is it's a modified E30 M3 engine, ie the S14B23 2.3ltr 4cyl lump, fitted with a turbo off a BMW Formula One car.
Well, that's NOT true, in fact it's WAY wilder than that!
The engine is in fact the BMW M12 race engine, ie an engine that's never been in any production car, and has been used in it's various forms and capacities, in Touring Car Racing, Formula 2, and was also the legendary 1.5ltr turbo BMW Formula One engine from the 1980s that was alleged to produce as much as 1400bhp in qualifying form.
This particular version isn't the 1.5ltr F1 lump, but is a modified version of the 2ltr turbocharged lump used in IMSA racing in the USA, used first used in the late 70s BMW 320 Turbo IMSA race car, making 650bhp at 9000rpm, then used in 1985 and 1986 in the BMW/March IMSA GTP race car, making 800bhp at 9000rpm.
Here's some pics from the engine in an original BMW 320 Turbo IMSA car...
Clear pictures of the later IMSA GTP engine are harder to find, especially as the engine was hidden under bodywork at the rear, but here's the car and some spec...
After the GTP car stopped racing in 1986, Arlid Martinsen, with the help of BMW Norway, managed to source one to use in his insane new rallycross build for 1987, and here it is...
Looks like it was made to be there eh! Fits lovely. Here's some closer up shots...
What we have here is, as said, an M14 IMSA GTP lump, 2ltr, heavily turbocharged of course, and in the spec in Arild's E30, it made 650bhp at 2bar boost, and was capable of 2.5bar boost if he wished, which although never measured, was without doubt going to be 700bhp+..
Internal spec was pretty typical as you'd expect for a full-on race engine, though one particular thing to note was Titanium conrods- Now that's flashy.
In 1987 the engine was 2ltr built by a famous Norwegian engine builder, but word is (from a good source too) in later years a 2.3ltr version was built for him by a Swiss engine builder.
As the pics show, it featured a big air-to-air intercooler, carbon fibre inlet plenum, twin scroll tubular exhaust manifold (everyone ran twin scroll back then- Madness not to as it really helps spool), HUGE single external wastegate (same one they used on the F1 etc engines), and a BIG single Schwitzer turbocharger (Schwitzer are now what's called BorgWarner Turbochargers, and they actually invented the ETT Extended Tip Technology compressor wheels before they became BorgWarner- In fact the entire BorgWarner S-Series of turbochargers, and therefore the majority of parts in SX, SXE, and EFR turbos too, use what was originally Schwitzer turbo parts).
Yep, Jubilee clips and rubber hose at 2.5bar boost... ;)
Perhaps what's MOST INTERESTING, and different, in fact pretty much unknown to most people these days, is this car ran FIVE throttles! In fact, so did the insane 1400bhp Formula One version of this engine too.
So yes, I can hear most of you already... "Five throttles? What the fuck are you on about? It's only got four cylinders". Well, do you want to play "Spot the throttles" on the next pic? Check it out...
Spotted them all? Well, it's not easy, but they're there! The first four are in the typical place for a race engine- Ie it's running individual throttle bodies, one per cylinder, right at the inlet ports of the head. So where's the 5th one? Well, look at the throttle cable, it comes over the strut brace, to the ITBs, then continues forward somewhere and disappears. But to where? Well look at the bottom right. As well as a big cone filter, what's that in front of the turbo? Yep, throttle number five!
Confused? Well I better explain then eh, that's what Stav-Tech is all about after all.
Well, it's a form of anti-lag that was used before anti-lag as we know it existed. And while it's not as effective as what modern ALS can potentially be (ie full boost all the time), and has issues (unless you have a specially modified turbo, you'll be sucking oil in to the compressor side badly when off the throttle, filling the entire inlet system with oil and making the exhaust smoke badly for a start), but done right it really is very effective- It was used in Formula One after all.
How does it work? Well, in essence it's the same as when you put your hand over the inlet on a vacuum cleaner, blocking the airflow. What happens? You can very audibly hear the motor speed up as it's doing less work, that's what.
On a turbo, the compressor side is the equivalent of the suction fan on your vacuum, and the turbine side is the equivalent of your vacuums electric motor.
With no airflow the fan/wheel has nothing to do, it's literally spinning in a vacuum doing no work at all, no air to push, and therefore the motor/turbine can turn far faster for any given power input to it (ie the electricity on the vac, or the exhaust gas on the turbine).
On a vac it serves no purpose, BUT on a turbo, if it's spinning far faster when off throttle, it also gets up to speed far quicker when you're back on the throttle; in fact potentially it's already at the required speed!
This is exactly what modern anti-lag does, ie keeps turbine rpm as high as possible even when off throttle, just done in a totally different way.
In related news, I want to test this setup for StavTech, as while it's got issues, A- I think I may have a solution to that, and B- I want to see, and show YOU, how effective it is!
Anyhow, back to the car...
While as I mentioned previously, details on these Rallycross monsters is scarce, but thanks to one of the top motorsport photographers from back then, the legend that is Eddi Laumanns (who took many of the pictures in this feature too!), I got hold of a feature on this car from a German car magazine when it was first built in 1987, and it has some VERY interesting details, in fact some of them can only really be described as pretty fucking insane.
The car was tested in the feature by Jochi Kleint, works rally driver for Opel, Ford, VW, and others in his career, and driver of the Golf Bi-Motor, the twin engine Mk2 Golf that VW entered in the Pikes Peak hillclimb in 1985, 1986, and 1987, with as much as 650bhp!
In the feature Jochi not only says the car feels at least as fast in a straight line as the Golf Pikes Peak monster, but he says it's very tractable, no need for 1st gear even in tight hairpins, and FULL BOOST is by just 4000rpm! A ~700bhp 2ltr turbo engine, making peak power at 9000rpm, but full boost by 4k! That's a 5000rpm+ power band, ie HUGE, far far more than 99% of cars even today, and this was 1987.
Like I've said before you can have all the new technology you like, but a correctly specced and set up engine even with very old spec parts will still wildly out-perform most stuff.
We've pretty much covered engine performance, so to finish this section off, and to go nicely on to the next bit, here's a great pic of the underside of the car, showing the big intercooler and 4inch exhaust system...
Anyhow, as bonkers as the engine is, the TRANSMISSION is probably at least as wild!
For a start, the gearbox is by possibly the best known brand from rallycross- Xtrac. What makes this special, especially for 1987, is not only are they ridiculously strong and capable of handling huge power and abuse, but they had in-car adjustable front to rear torque split, which on this car was meant to be between 28F-72R, right down to 50F-50R.
In the magazine testing Jochi stated he felt the car was fastest at 40F-60R.
The transmission had another setting too, again selectable from one of the buttons within reach of the driver, and I don't know if this was a 1-off for this car or a feature of other Xtrac transmissions of the time, but it's deffo the first time I've ever heard of it- It had a BOOST OPERATED four wheel drive!
Yes, you read that right. One of the settings this car had made the car 100% RWD until boost pressure hit 3psi (0.2bar), and then the 4wd would kick in! Clever as hell, especially 30 years ago!
In theory I can imagine an advantage on turn-in off throttle to eliminate understeer, as chances are this car had a pretty serious plated LSD front diff, but according to Jochi in the magazine feature, he felt it was faster when in permanent 4WD mode.
Away from all that madness, the clutch was a Sachs triple plate item, the front diff was based on the E30 325iX setup, the rare factory 4wd version, and the rear end and diff was full Group A E30 M3 setup. This is a pic of the rear end actually...
And here's the front suspension setup..
The interior of the car was pretty sparse as you'd expect from a race car, but notice the bank of switches, most of which within reach of the driver to adjust the trick 4wd system settings, not to mention the all important boost pressure.
For cooling, the car had what has become a bit of a trend for drift cars and even some Time Attack cars in recent years, and that's a rear mount radiator, and you can see the holes and ducting for it in these pics...
As well as the radiator, there was two other things in the boot of this car, two VERY unusual things, something to mental that if it wasn't for me reading the words in this very sensible and technical German magazine who tested and reviewed the car when it was brand new, I'd be 100% they were joking...
It had the alternator and A MOPED ENGINE in the boot! Seriously! It really says that! It says it has a small moped engine mounted in the boot that has the sole job of spinning the alternator, which in turn gives the electricity for all the trick parts this car runs. Crazy!
So, I've already mentioned that, despite it being absolutely incredible and hugely spectacular, this car wasn't actually very successful in rallycross.
According to Jochi Kleint in the feature, the car was almost undrivable as it simply had TOO MUCH POWER for the tyres and suspension to handle, even with the trick 4WD system, and he felt on loose surfaces a well-sorted 200bhp FWD Golf would be as fast if not faster.
The feature also says the owner/driver, Arild, was having to change tyres after every race, which wasn't normal for rallycross, and was due to the combination of massive power and running hugely soft tyres in an attempt to get decent traction.
There's another alleged issue too, which does tally up with the fact the car always seems incredibly tail happy, and it's said in recent years his son has talked about the car and stated the 4WD system or the front diff at least wasn't actually working like it should, making the car far more rear-bias than it was meant to be.
Either way, win or not, the car has become a bit of a legend and deffo my fave car, and even Arild himself is said to be incredibly surprised people now, 30 years later, still talk about the car. He will probably be a lot more surprised if he sees this feature!
.ANYHOW, that's about it for this feature on this insane and amazingly interesting car, and I hope you've liked reading it as much as I loved writing and finding out about it.
There's a LOT more incredible cars from this era of rallycross, and as long as you guys want to hear about them, and as long as I can find out the long-lost info about them, you'll be seeing more features like this in the future!
Also, please, if you liked what you see, and want to see a lot more, want to see and read exclusive content and even get help on your own project, help Stav-Tech grow to bigger and better things by becoming a patron of the brand, giving whatever you feel it's worth to you, simply by following this link- www.patreon.com/stavtech.
Of course, don't forget to check out the StavTech Facebook and YouTube channels too, as I regularly post great stuff on both channels, so don't miss it!
Since I created the StavTech YouTube Channel (Click here!) I planned to put everything on there from now on, as unlike here, there's money to be made, and I need to make a living after all, BUT some things just work better as words, so I've decided some things will be on the website regardless (plus Facebook and Instagram), so here we go...
A few weeks ago I saw a post where a bunch of retro-rallycross fans were confused about the strange 'loop the loop' inlet manifold in the above picture (by rallycross photography legend Eddi Laumanns), and were discussing what the hell it was all about.
I replied and explained exactly what it was, but I got the feeling they didn't really believe me. It was only once someone posted a clearer pic that proved I wasn't talking out of my arse that they finally seemed to accept it.
BUT the whole situation made me think it's ideal as a cool bit of tech for you lot, so here it is!
This funky looking inlet manifold is used only on certain variations of one engine, the XU8T, which is the 16 valve turbo race engine version of the PSA (ie Peugeot + Citroen) XU series of engines that are found in countless production cars, and was first used (unless very late spec 205 T16 Evo2 Group B engines used the same? If so I've never seen one!) on the 1987 Pikes Peak 205 T16, ie this one...
It was then used the year after in the 1988 Pikes Peak winning Peugeot 405 T16, the world famous car driven by Ari Vatenen which starred in the famous 'Climb Dance' video.
In fact, here's a few pics of this inlet as fitted to the 405 T16 Pikes Peak winner...
The next time this inlet was seen on a car was in Matti Alamäki's 205 T16 E2 rallycross monster in 1989, which made well over 550bhp from it's 1760cc (I understand? Slightly less than the GrpB versions for some reason?) engine...
Soon after this it also found it's way in to Jean Luc Pailler's Citroen BX4TC rallycross monster...
And after a good few years Jean Luc Pailler pretty much swapped the engine and running gear in to the BXs replacement in the production car world too, the Xantia, where it was used for the number of years in the 1990s...
ANYHOW! Enough of the history lesson... What the FUCK is that crazy looping inlet all about then?
Well, it's actually a lot more 'normal' than you might think...!
As crazy as it looks, all this inlet really is, is a variable length inlet manifold like a lot of production cars have these days, albeit a super trick one running two sets of individual throttle bodies, really long runners (which should have a far greater effect than typical ones), and a boost-operated (rather than rpm) switchover point.
Variable length inlet manifolds are quite common these days, used on everything from MX5s to Ferraris. As you probably know, in conventional inlet designs, longer inlet runners tend to improve low rpm performance at the expense of high rpm performance, short runners improve high rpm at the expense of low rpm performance, but a good variable length inlet should be the best of both worlds.
The common myth is that inlet length makes no difference to turbo engines, hence why it's rare to see factory turbo cars with them, but in reality it makes a difference no matter what; it's just turbos are so good at making a wide powerband, and masking flaws in an engines powerband, that they're rarely used on boosted engines.
Rarely used or not, it doesn't take Sherlock Holmes to work out that if Peugeot, who were one of the world leaders in turbocharged motorsport at the time, used it on multiple Pikes Peak cars, including an outright winner, and then it was used for about another decade in high end rallycross, it's fair to say it had a very worthwhile effect- They didn't fit stuff for fun or just guessed at that level, that's the stupid shit road car tuners do, not them!
The main reason they fitted this inlet to these engines was to improve low rpm performance via the long runners, which has the positive side-effect of spooling the turbo faster, while also having the switch-over to short runners, shorter than most typical non adjustable inlets, for maximum high boost high rpm power.
The engines this inlet was used on were as small as 1760cc and up to only about 2.1ltr, but all made somewhere between 550 and 800bhp depending on the application; we're talking really big turbos that needed all the help they could get to spool, especially for the tight and twisty rallycross and Pikes Peak events they were used in.
So, what are we actually looking at here? Well the top-down shot of it mounted in the Citroen BX is a good one to check out... Follow the boost pipes!
The air comes from the filter (bottom right), through the Kevlar inlet pipe, and in to the turbo compressor housing (top centre). It then leaves there and enters the chargecooler (top right), then heads down to a centrally mounted plenum as part of the inlet manifold this feature is about (middle right).
Just to the left of the central plenum are 4x individual throttles, one per cyl, but these aren't the engines main throttles, these are simply to block the short inlet runners, forcing the air to go around the long looping runners you see exiting the right hand side of the centre plenum.
The aforementioned throttles are opened at a set boost pressure via the turbo wastegate style actuator you can see painted black on the right hand side of the inlet, near the air filter outlet.
The engine itself also has 4x conventional throttles, one per cyl, but they're mounted VERY close to the inlet ports, and are pretty much invisible in the above shot, but you can see the the springs and rods that operate them on cam cover.
For a MUCH clearer view of both sets of throttles, which will also easily show you how the inlet works, check this pic out...
This style of inlet isn't seen in modern motorsport anymore, mostly as modern anti-lag systems are so effective at spooling turbos, which makes setups like this a bit redundant for most race works race engines which have pretty unlimited budgets.
Having said that, this style of inlet makes no noise, adds no engine stress or heat, and is purely mechanical, so for us road car based people, indeed for race car people without a works race team budget, variable length inlets do potentially have a worthwhile use on turbo cars, despite what many people think...!
Or do you (think you!) know better than Pikes Peak winners...? (Hint- You don't!)
I was all set to do a big feature on the fact that, while low down and mid-range torque makes a car nice to drive, easier to drive fast, and is handy if you got the traction to use it, it's mostly BHP that makes a vehicle fast.
That's providing you can stay in the powerband in your BHP car of course- And if not, it's not torque winning races, it's because you've got a massively flawed setup that's losing you races.
BUT it turns out I did one of those features about a year ago! If you've not already read that, check it out first, as that covers 99% of the points so no need to repeat myself.
Check it out HERE- bhp-sells-cars-torque-wins-races-total-bollocks.html
ANYHOW, I found some performance data from when I timed some tuned Turbo Diesels at Bruntingthorpe Proving Ground some years ago, and I think it explains my point well. Of course, the results are just as relevant to low rpm low BHP high torque V6 and V8 petrol engines too, so that's what Part 1.5 is all about.
Basically, torque FEELS fast.
Even my 1.9TDI PD100 Skoda Fabia daily driver FEELS quite quick, as it's got 180lb/ft at barely over idle, so you put your foot down, turbo spools, and it accelerates very hard at low rpm. Try that in something like a typical performance 2ltr car, say a EP Civic Type-R, and it will accelerate slowly and not feel fast at all.
But does that mean my Fabia is faster than a Type-R? Fuck no. Not unless the Type-R driver doesn't know how to change gear and is driving around at low revs. Even though at peak torque a Type-R is a good 30lb/ft down on my shitbox Fabia, it's got about 200bhp, so, as long as the driver is in the ~6000rpm+ rev range, it will leave me for dead like I'm not moving.
Diesels often SEEM like they're faster than a lot of cars when on the road too, and that's because cruising rpm and maximum performance rpm are about the same. You're pottering along in 6th in your tuned TDI, getting your great MPG, and you see a something quick you want to try and race come up behind you. All you have to do is put your foot to the floor, and fuck me, off you go in a cloud of smoke and big torque, and next thing you know you've 'won the race' and you're screaming "No smoke no poke bitches! Black smoke racing! WOOOOOOO!" to yourself like a fucking lunatic and you've left the bird in the S2000 wondering what the fuck just happened.
Why'd you leave the other car for dead so easy? Because unless they'd already dropped 2 or 3 gears (3 for anything N/A with a small high rpm rev range) ready to race you, which is unlikely, fuck, even less likely as most typical car drivers wouldn't even realise they'd need to do that to go fast, you've left them for dead before they even realise they're in the wrong gear.
But what would happen if they were in the powerband? Well, if you've got similar or more power to weight, you will likely win, but if you've got a torquey diesel but making less power, you're still gonna lose a 'fair' race.
When it comes down to it, it's your POWER, more specifically POWER TO WEIGHT, that is the big key providing the cars are in the rev range.
Saying a diesel is faster as it's faster up to 4000rpm is like saying some hunk of shit 1ltr petrol car is faster than a quick diesel just because it's faster from 5000rpm on. Unless your car hasn't got gears, or you don't know how to drive, neither are excuses.
ANYHOW, ON TO THE DATA I WAS ON ABOUT...
Back in 2010 Redline did a 'Diesel Special' issue, and one thing we did was time 3x Seat Ibiza TDIs in different stages of tune.
We did this to see, or prove even, if it is worth tuning diesels. I think we all know the answer to that, and it's FUCK YES. Diesel tuning gives massive gains over the original performance, and unless you go totally spastic you keep your drivability and economy too- In fact as a daily tuned car, esp if you do a lot of motorway driving, a tuned diesel makes the most sense of all- Great all-round fun daily cars.
The thing is, what this feature ALSO shows, is how fast, without any bullshit like both cars starting from 1500rpm in 6th, how hard these cars, all with huge amounts of torque, accelerate.
And the answer is pretty much what I said in Part 1 of this feature, and indeed in this 1.5- Only about as fast as a petrol one with the same BHP PER TON would...
Ignoring standing start times, which are never going to be good for 2wd cars with tons of torque unless you've got drag tyres, let's look at the most real world, not traction limited, and easy to compare times, 60mph, to 100mph.
So, let's start with a stock PD130 Ibiza 60-100mph time (real time, not bullshit speedo time)- It's over 20 seconds. Not fast, 230lb/ft of torque or not.
An EP Type-R, with only 145lb/ft, is 9.6sec, in fact other similar hot hatches like Clio 200s and R53 Mini Cooper S's also do it in the ~10sec range.
A late spec Mazda 3 MPS is 8.2sec, but has over 50bhp more.
So what about with some minor mods, to 145bhp and a pretty huge 270lb/ft- About the same torque a Ferrari 360 has, and that does 60-100mph in a touch over 5sec, and is over 150kg heavier than an Ibiza TDI!
Well, 60-100mph time is 19seconds now, very noticeably quicker, but still, nowhere near as fast as the similar weight cars with more BHP.
In fact, it's about as fast as other similar weight cars with 145BHP, funny that...
So what about when we do about the most common level of tune for TDIs, ie a remap, intercooler, and exhaust? In this state of tune they have around 180bhp and a bonkers 310lb/ft, the same power as the 1.8ltr 20V turbo petrol Seat Ibiza Cupra model, and that does 60-100mph in about 12sec, but the Cupra has 130lb/ft less torque than this, so...
Oh fuck me, lo and behold, it's WAY faster than the less tuned one, it's a legit quick car, but despite mental torque, it's 60-100mph acceleration is almost identical to a 180bhp Cupra. A 180bhp car is as fast as another 180bhp car? Surprise? Well, no.
Last, and deffo not least, as it was legit rapid, a semi-stripped Ibiza TDI with 245bhp and 410lbft! An Audi R8 V10 has 20lb/ft less torque than that, and weighs about 500kg, half a ton, more, and is 60-100mph in about 4.5sec.
SURELY, IF torque wins races (Spoiler alert! It fucking doesn't!), surely being half a ton lighter and having 20lb/ft more would make you way faster, right?
AND THE RESULTS ARE! Well, unsurprisingly, it's about as fast as a 245bhp ~1100kg car would be!
It's rapid, it's mental fast vs the stock car, but it's 60-100mph time was 8.8seconds- Much faster than hot hatches with ~40bhp less, and, lo and behold, what a similar BHP PER TON hot hatch does. Funny that!
I raced him in a Lexus IS-F (A fucking fast car- I did 60-100mph in 6sec in it that same afternoon) afterwards, and it was bizarre only being able to pull away from what looked like a Mum's school run diesel from 30-120mph fairly slowly (destroyed it beyond 120 as TDI ran out of gears, but to be that close is still a FAST car), but it wasn't the torque that made it that fast, it was the fact it was a pretty light (IS-F is 1700kg!) 245bhp car!
I think we all know diesels can be CRAZY fast, fuck me, the Darkside Developments Seat Arosa TDI runs 9sec quarter miles at ~150mph! But it ain't the torque as such (But power IS torque and rpm combined), it's the fact it weighs nothing and has well over 500bhp! Check it out, it's fucking mental....
I think between what was said in PART ONE, and the results from this one, says it all.
Torque is useful, torque is enjoyable, torque is fun, torque feels fast...
...But does TORQUE WIN RACES?
FUCKING FUCK NO, BHP WINS RACES!
ACTUALLY... Torque and RPM combined win races, because...
Torque x RPM ÷ 5252 = POWER
As we all know and have experienced, the car world is a hive of bullshit and excuses, as people can never admit anything is their fault, so either blame the car or someone else.
From people blaming poor performance on a misfire when it's actually shit driving or them lying about how quick their car really is, to companies not honouring a warranty by making some kind of excuse to blame it on user-error- Excuses are a 'car thing'.
The inspiration for this mini-feature was hearing one of the most ridiculous excuses I've ever heard, and something that I'd not heard for about 15 years, and even back then it blew my mind someone supposedly respected had the balls to claim this...
Step back to 15 or so years ago, and the first example of this was about the Skyline GT-R RB26DETT engine, and most notably the ceramic turbine wheels the turbos have, which are known to snap off the shaft or shatter to many pieces.
While the above is an unfortunate and common fact, one of the big name tuners of the time used to convince their followers they needed an engine reubild as soon as this happened, as bits of the turbine wheel will have been 'sucked' in to the engine.
Some of you right now might be thinking "Well can it?", and some others are thinking "WTF?", so let's break it down in to a way even a tuning novice can understand...
Fast forward to today, and I heard a very similar thing, used as another bullshit excuse, but actually even more far-fetched in my eyes.
The basic story is an engine has severe pitting (IMO severe detonation, but that doesn't matter for this) on the squish/quench pads on all cylinders on a turbocharged engne, and on the exact same opposite areas on the pistons too.
No marks anywere else- Untouched bores, untouched centres of pistons, untouched valves, untouched combustion chambers- Basically only the areas most affected by det.
Certain people (And to make it even more stupid, these people AREN'T the tuner either! This is honestly people just trying to defend him off their own back, despite it not being strictly blamed on him- Retarded or what) flatly refuse to see it as detonation, and claim it's FOD (Foriegn object damage), and back that up by the fact ONE of the cylinders has broken a piece of valve guide off in an inlet port.
My comment was "Even IF somehow it can only damage areas either side of the piston/chamber without touching the center or the bores, how can FOD in one cylinder account for the same damage in all the others?"
The reply was "Doesn't matter which cylinder was damaged, if one goes they're all going to get damaged as the metal will travel back up the inlet manifold and in to the other cylinders"
Again, some of you are already thinking "WTF", as it's probably even more far fetched than the first, despite being said by a bit of a hero of the tuning scene, so let's once again break it down...
So yeah, more utter shit.
The WORST thing about all this kind of crap is though, is that this isn't words of random idiots, the 2nd example wasn't even from a tuner making an excuse either- This is coming from RESPECTED names in the modified car world, 'FAMOUS' names some might say, and because they're "Somebody", people blindly believe them, despite it being insanely far fetched.
My question of it all is, do they BELEIVE what they're saying, or are they LYING? Either way it is REALLY fucking bad considering they're influential, aspirational, whatever the fuck you want to call them, names, in this stupid hobby we all have.
And this is exaclty why I'm hugely skeptical of what even 'Big' names say, partly by being untrustworthy, partly by not knowing as much as you think (or they'd like you to think) they'd know.
It's terrible really, being a skeptic or having trust issues isn't a good thing, and it'd be amazing if this tuning world was just people being honest and helping, but instead the kind of people and the kind of advice in the tuning scene is a big reason why so much of it is fucking awful and so slow progressing.
You have 2 choices, you can either listen to these people and be one of the crowd getting ripped off or having mediocre stuff, or you can take everything you hear with a pinch (ok, a fucking huge road gritter full) of salt, and fact check stuff from even supposed big and trustworthy names, which should, while it's a lot of work, get you a seriously good car.
While it's popularity and media coverage is increasing in recent years (Yet it was on prime time TV on in the 70s and 80s- A long way to go before it's back at this level!), Rallycross is, in my eyes anyhow, the most under-rated motorsport there is.
And more than under-rated, it's genuinely fun to watch, and by far the most relevant to UK tuning fans of any motorsport.
Formula One is world famous and has the biggest budget of any motorsport, but is it exciting to watch? Not really. And it's all so secret that any possible relevance to the tuning we all do we either won't know about for decades, or never will.
WRC cars in 2017 will be the most powerful than they've been since the GroupB days, but it's still not a great spectator sport, despite being hugely famous and featuring wild cars.
BTCC is hugely popular in the UK, and as circuit racing goes, it's pretty badass, but in my eyes it's not even a patch on Rallycross, and strict rules make things quite samey too.
I've seen people talk about Rallycross like it's fucking Grasstrack oval racing, in fact I've seen the same people go "If you want to see a real mans sport, check out BTCC". FUCK knows what they've been watching, but it sounds like they've never seen Rallycross in their lives.
If you haven't watched any before, go check some out on YouTube or something. 600bhp 700lbft 2ltr flame throwing anti-lagged 4wd turbo cars door to door, sideways everywhere, on a twisty track which is a mix of tarmac and gravel. As the races only last 5 laps (It was usually 2.5 laps in the 80s/90s), so unlike most racing, it doesn't have boring parts where they're trying to save the car, or tyres, or engine- It's flat out from the start to the end.
Anyhow, as I love tuning (and presumably if you like Stav-Tech you love tuning too), the main reason I love Rallycross is the insane acceleration of these things, and that's because the engines are fucking MENTAL...
In recent years engines in the top class are restricted to 2ltr (turbo, of course!) and with a 45mm inlet restrictor, which keeps power back to around 600bhp and 700lbft of torque, though previously there was no restrictor as such, but instead different minimum weight classes depending on engine capacity.
Things did vary country to country, year to year, but for example, in the late 80s early 90s in the UK, the 4ltr class, which mostly consisted of 2.3ltr turbo engine cars (turbo or supercharged meant a multiplication factor of 1.7, and 2.3x1.7 is a touch under 4ltr), had a 1100kg minimum weight limit.
Cars in this class were things like Will Gollop's Metro 6R4 which was the V6 de-stroked to 2.3ltr then twin turbos added, giving it 750-800bhp, and other similar crazyness, such as the 4wd Turbo E30 BMW M3 of Arild Martinsten which also had 750bhp+
Due to the various weight vs capacity classes, it was common to see 1.4ltr to 3ltr+ cars all in the same race, and due to the lighter weights and the fact almost everyone had BIG turbos fitted, everything was, just like it is now, fucking mental fast.
You'd imagine maybe that everyone would be aiming for the 2.3ltr turbo engine for the maximum power, but this wasn't actually the case, as these were days before seriously effective ALS systems, so power was always a trade-off with lag, and also, when it boils down to it, on a slippery gravel surface with few straights there's not much grip or opportunity to use big power.
It was often said that around 550bhp was the maximum usable power, and many ex-GrpB cars either stayed at, or were even de-stroked to around 1.8ltr, which was enough for their 550bhp power goal, but allowed them to be much lighter than the 2.3ltr turbo cars.
Having said this, there were some cars with MUCH more power, 750bhp+, but if you watch old Rallycross videos on YouTube it was spectacular but unless they were in the lead it was very little use on the twisting tracks, and usually have about a 2second oppertunity of full power per lap!
Here's a few older rallycross engines. I say a few, as despite the wonders of the internet, it's not a time machine, so despite some pics being uploaded from the 80s and early 90s, there are literally NO pics around of some of the greatest, wildest, and most interesting rallycross engines ever made.
Gollops twin turbo 6R4 lump? Nope. Martinsetens F1 Turbo M3 lump? Nope. All the countless Group B 205 T16s, Delta S4s, Audis, etc made better than ever that ran in Rallycross? Nope. Unfortunately there's very few pics out there on internet land, which really annoys me, but here's a few...
In the 80s Renault Gordini turbo engines (Which are, in essence, the Renault 5 GT Turbo engines, but with a better, crossflow, cylinder head), from 1.4 to 1.6ltr were popular and used in both Renault and Volvo rallycross cars, often pushing well over 350bhp, and as they were fitted to cars that weighed well under 900kg, it's fair to say they went like hell.
Another mega successful and popular engine in the 80s and even 90s were turbo'd versions of Ford BDA lumps, often built by Zakspeed, from 1700cc upwards, and pushing out well in excess of 500bhp.
Beetles were popular in 80s rallycross too, with all kinds of specs, including 4wd turbo versions, like this one that's still around to this day...
Most interesting about this one is the engine, which is still a VW block, but as Rallycross rules allow any heads to be fitted, it's got Subaru heads...
One thing I'd like to know, and I've yet to see pics or info confirming it, is turbo position on this Beetle. Going by what I can see, I'd say it's mounted inside the car, where the rear seats would normally be, which is pretty cool. In fact I 'think' you can just about see it through the hole in the bulkhead on this pic...
Rallycross gave a new lease of life for the Group B cars after they were banned from rallying too, showing what they could have been like with more development, making them wilder than they ever were in rallying. Check out this Citroen BX4TC. They were rubbish in GrpB due to lack of development, a total disaster, but in rallycross it got it's chance to be as mad as it should've been, and they were fucking weapons...
If you're wondering how batshit crazy fast these cars were, even in the mid 80s, check out this article from 1984. No it's not in English, but enough of it is written in words we understand to get the rough idea of the 1984 spec of Rallycross legend Matti Alamaki's Porsche rallycross car...
So this is 1984, and this Porsche 930 has 4 wheel drive, a twin turbo 3.2ltr flat six pushing out 750bhp and 6200rpm, and weighs, well, 1130kg I think? Check out the old-skool timing gear wheel on the back in the main pic too! Now page two...
0-62mph in 3.1sec (so 3sec dead to 60mph), 0-100mph (160kmh) in 5.7sec, and 10.5sec quarter mile time. And this is 1984, 32 bloody years ago!
EDIT!!! You might think the above acceleration sounds mad, and it is, but according to one of our helpful Finnish readers (who can read the above words, unlike me lol), those times were not only done in the WET, but the cars stop speed is 206kmh and hit it by just 260m, so did the last 140m just bouncing off the rev limiter in top, no more acceleration!
So if it had the gearing for it, and a dry surface, that car is easily in the 2s to 60mph, 4s to 100mph, and running 9second quarter miles.
In 1984, and not remotely a straight line drag car. Crazy shit right there.
Rallycross is also where you see the engines that, while we all NOW know are massively tunable, have often been tuned to 600bhp+ for decades already. But as most people don't notice race engines, and just look at tuner cars for inspiration, people never realise. Like Saab lumps...
Or the Opel/Vauxhall C20XE...
Rallycross is amazingly unknown by tuning fans in the UK, and to me I find that fucking bizarre, as frankly, the engines are THE most relatable to the shit they do of any motorsport; just usually way, way better.
I mean, look at all these engines so far, they are ALL stuff you'd recognise from typical big power tuned engines we love to see in road/drift/timeattack cars, but frankly, these are usually done far far better, and cleverer, by people who know what they're doing rather than just pretend to.
Not many parts on Rallycross engines are bits you recognize as the big money off the shelf tuner parts everyone likes to fit to their road cars though, as funnily enough, despite the hype, those bits are rarely, if ever, the best designs.
That to me is a big reason why I love Rallycross- The engines are something I know, understand, relate to, agree with the design, and more to the point, they're my inspiration when tuning- Not some nobhead with a lockup who calls himself a tuner.
THESE are the engines you should look up to in my eyes, not some shiny shit you see on FB, but more on this later...
ANYHOW, moving on to the '00s to present day, Rallycross top classes around the world mostly changed to a 2ltr turbo class with an inlet restrictor (This was in 1997 if I remember right in Europe, and maybe 2003 in the UK?) to hold back power to vaguely sensible levels as things were getting ridiculous (and frankly, with today's tech, a 2.3 non-restricted turbo engine like the old days, would now have about 1200bhp, and costs would be fucking insane), though this 'vaguely sensible' level is still about 600bhp and 700lbft, which frankly is insane fast, like '0-60 in sub 2sec on tarmac' sort of fast.
This is the usual 45mm turbo inlet restrictor fitted...
Though at least once a twin turbo setup was attempted, which meant two smaller restrictors instead...
One other big advantage the newer (and by that I mean in the last 15yr or so) engines have, despite less power than some of 80s ones, is fucking everything has something very noticeable fitted, usually a setup made Swedish company Tibuc...
What the above is, well, the 2 blue hoses coming from the box on top of the plenum to the box after the throttles, is the electronic adjustable air bypass valve, a fucking big air bypass too, for the anti-lag system. And ALS is, if you speak to most Rallycross drivers these days, is THE most important part of the engine.
The engine performance difference ALS makes is an incredibly hard thing to imagine unless you've experienced a really seriously good working system yourself, but the difference between it being on and off is like two different engines, and the difference between being competitive and not in Rallycross.
Realistically, the 2ltr turbo engines of current cars, without ALS activated, are going to have a powerband of 4000rpm+ and not the most responsive things when on and off throttle either, as the turbos fitted are BIG.
A small high rpm powerband and poor throttle response is NOT ideal for Rallycross, which is incredibly close and tight, on and off throttle constantly, and where a whole lot of the cars steering done with the gas pedal rather than the steering wheel.
Basically, if you switch the ALS off on a Rallycross car they will get left for dead by the other cars with it active; you just can't compete without it.
With ALS on (and Rallycross ALS is mental, like full boost all the time regardless of revs and throttle position style, proper fucking mental), the cars are totally different animals, like driving an 12ltr+ naturally aspirated engine that somehow also revs really high, rather than a typical 2ltr big turbo engine- Basically you get BIG torque and instant response constantly, regardless of revs.
Some more pics, all with Tibuc ALS setups, as almost everything had/has it...
As the above pics might hint, Cossie YB engines dominated Rallycross from the late 90s until recent years, as despite what the Jap fanboys etc like to think, if you wanted a 2ltr engine that could bash out 600bhp/700lbft and win you races, the YB was the one to have. How many SR20s have you seen in Rallycross? I can think of one tbf, in Finland, in a Mazda RX7..
But again, variety has always been key, I mean, here's a Mitsubishi 4G63...
And here's a VW lump...
Going bang up to date now to the present day, while the engines are the same principle, some of the ALS systems are even more advanced, more like mega power versions of current WRC engines, and now the airflow bypass isn't just past the throttles (though it usually is too, via fly-by-wire throttles now though more often than not), but it's direct in to the exhaust manifold via a valve and a series of pipes, which is more efficient.
This particular ALS system isn't actually new though, the earliest versions of this were used on the Audi Group B rally car in the mid 80s.
This ALS system is the valve at the front by the exhaust manifold on the below pics, and the small bore pipes from it is feeding air to each exhaust runner.
Anyhow, regardless of age, the fundamentals of turbo Rallycross engines hasn't changed in 30odd years, and they're still fucking awesome and even the oldest ones should be the inspiration to most of us tuning turbo cars in my eyes.
I'm not saying copy them exactly, as I dunno about you but I sure as shit can't afford to build a 700bhp/700lbft 4cyl turbo crazy thing, but what I mean is check them out, check out what they do and often DON'T do, as you can be sure as shit they do or don't do it as they know what's best.
Not sure what I mean? Well...
For example, people often get all giddy and excited telling the world about their amazing boost pipe clamps that cost them about 50quid each, and those same people tell the world jubilee clips are shit and don't hold under high boost, etc etc, usually despite the person saying this having a car that don't even run a lot of boost.
WELL, let's look at some Rallycross engines shall we? Money is NOT an issue for them, they are mega spec, the best of the best. The engines often run 3bar+ peak boost. But what holds the vast majority of their hoses on, from the early 80s to the present day? Yep, that's right, normal Jubilee clips.
YES, shit twisty soft Chinese shit fake Jubilees are junk, but proper ones are strong as hell, can be done up mental tight, and hold a fuck sight better than most the wide Mikalor etc etc ones people like to shout about loudly on the internet.
What about massive fuckoff inlet plenums like so many people pay big bucks for on their tuned road cars with barely 200bhp per litre? Well, these Rallycross cars are 300bhp/litre+ and do they have massive plenums? Fuck no, as there's nothing good to gain from it at all, and plenty to lose in response. A better than standard plenum? Yes. But IMO 80%+ of aftermarket plenums are just some badly designed, often oversized, shiney shit that does no good barring lighten your wallet.
I've mentioned it in the past, but what about big cone filters in the engine bay? If you listen to internet car experts, they suck in hot air and kill ruin performance, seemingly oblivious to the fact ENOUGH air matters 100 times more than COLD air. Thankfully Rallycross people aren't keyboard tuners, and as the pics show, they put a massive air filter where ever it fits best.
Oh, here's a good one you can see in these pics that everyone in the tuned road car world ignores, fucking TURBO HANGERS.
On the internet you can't fail to read people constantly crying as their turbo manifold has cracked, or the bolts have worked loose, for the 20th time this month.
What gets me is peoples solutions, or advice, are all kinds of crap, such as fancy bolts and fasteners, different exhaust designs, even fucking welding the turbo straight to the manifold like they're auditioning for fucking Roadkill or something.
But despite all this, never do they have the sense to look at pretty much ANY proper race car and notice they fucking ALL run turbo hangers, taking the weight of that bloody turbo off the exhaust manifold, off the exhaust system, off the exhaust nuts, and bolts, and studs, and gaskets, and everything else that fucking breaks. And lo and behold this stops them breaking.
Dunno if I ever mentioned it before on here, but on my old Cossie (they have a form of turbo hanger fitted as standard, nothing fancy, but they have them) I ran 2 years no issue at all without anything blowing, leaking, cracking, anything, despite 30psi boost, anti-lag, and serious abuse. THEN my turbo hanger got a bit tired looking so I removed it to sort it out, presuming it'd be fine without it for a bit (this was like 2002, I knew no better), and within a WEEK it was blowing at a join due to loose bolts, and from then on it would loosen bolts or blow an exhaust gasket within a few days of doing them back up.
Refitted the hanger a week later and it never happened again.
That taught me a lesson for sure, but despite telling people for about 15 years since that their issues would be solved with a turbo hanger, does anyone listen? Do they fuck, you still never see 'em.
And the above are just a few examples of the many many many things just checking out some proper race car engines, and ignoring typical shitty tuner cars, will teach you.
And ignoring teaching you anything, go watch some fucking Rallycross, it's mental! There's tons of 80s, 90s, and current Rallycross all over Youtube, and in fact, if you wanna see the craziness of modern ALS on Rallycross cars, find some vids of the Gymkhana Grid Championship finals in Greece from last weekend (ie end of October), there was various Rallycross cars in that, most notably Liam Doran's Citroen. The finals was at night, so it's flames galore, and by the end of a 1min run the entire exhaust, right to both tailpipes, was glowing red hot- Properly amazing looking.
So yeah, Rallycross is awesome, and Rallycross engines are surprisingly educational AND awesome. Check them out...
Brian Hart isn't a name many know of these days, but from the 70s to the 90s he was a bit of a legend in the UK tuning world, especially the Ford world, and this feature is about the wildest engine he and his small company produced, the Hart 415T.
While Cosworth famously initially produced the legendary Ford BDA engine, what most don't realise is that is was Brian Hart that made is the success it was, producing the 2ltr BDG version that dominated the World Rally Championship (and practically every other rally worldwide) in the 1970s, and it was also him who developed the full crazy Group B rally version of the RS200 BDT engine, the BDT-E.
Anyhow, what was known in the Ford Motorsport world as the BDG was initially developed by Brian Hart as a Formula 2 engine, firstly as the 420S, then in full developed, kick ass, practically nothing left of the original BDA (not even the block) version, as the 420R. Hugely powerful for it's size and weight, and there's versions right up to 3ltr that's been made, and still are to this very day.
The Hart 420 kicked ass Formula 2 from 1976 on, and it was so good that the Toleman F2 team agreed in 1978 to help finance development, which clearly worked, with the engine taking Toleman to a 1-2 in the 1980 championship.
And this is where shiz gets interesting, as for 1981 Toleman decided to step it up a notch, and despite being a small team vs the big manufacturers, they decided to enter Formula One, which by now allowed either three litre naturally aspirated engines (the Cosworth DFV still powered most F1 cars by then, though Alfa and Matra both had versions too- 14 out of the 17 teams used non-turbo engines), or 1.5ltr turbo engines, which Renault, Ferrari, and Toleman chose to use in 1981.
As Brian Hart showed his amazing talent for mental 4cyls, it was decided that was going to be the new format for their 1981 F1 1.5ltr Turbo engine. Bear in mind this is a small team, and a small tuner, producing his own engine from scratch, to compete against engines built by some of the biggest companies in the world. A serious David vs Goliath battle, it seems and insane plan, but they did it...
The Hart 415T engine looked similar to the 420R, and they were both 4cylinder 16valve engines, but the 415T was another ground up development by Hart, a 1.5ltr purpose built turbo engine that was actually a monobloc, ie the head and block are cast as one piece- No head join = No head gasket to blow!
According to an old issue of MotorSport magazine at least, until this engine Hart had never seen a turbo in the flesh, didn't understand intercooling (might explain the chargecooler- reality>theory!), and the original 1981 engines were NOT monobloc either, though how true that is I don't know (Maybe just test engines weren't mono? that'd make more sense, but I've not found that info out).
Unfortunately, as with all this old F1 Turbo stuff, most the truth is lost because of both secrets and age...
Anyhow, here's some bare engine pics you can click on to check out the construction of this all-alloy monobloc lump. Note no head to block join, 4x throttle bodies, and individual external water ports above and below each exhaust port.
The 1981 and 1982 seasons used a single Garrett (I've heard KKK mentioned too, but never confirmed this to be true) turbocharger mounted on top of the engine, and an alloy chargecooler under the inlet manifold to help keep temps down. Here's a 1981 engine, which made a touch under 600bhp in the race, and I think 700odd in qualifying...
This is a 1982 engine I'm fairly sure, much the same basic setup, but a nicer manifold, especially for the wastegate take offs. These were also, as per all F1 Turbo engines of the era, a little more powerful than the previous year, as development progressed.
Here's a few more early spec 415T pics showing the chargecooler etc, before we get to the big change and where things get really interesting...
ANYHOW, the 415T engine so far, while getting a lot of praise for being a pretty amazing and strong engine considering it was developed from scratch by a very small UK firm with an absolutely tiny budget (in Formula 1 terms at least), it was still down on power versus the others, and while it often showed flashes of it's potential, the results so far didn't really materialize.
With bigger sponsors and therefore bigger budgets appearing for 1983, the layout changed a little, with the engine looking a bit more conventional; a big intercooler, and the turbo mounted to the side on a long runner tubular manifold. Power was up, and the car overall was better, scoring points in the last 4 GPs of the 1983 season- Finally starting to show what this clearly very strong and capable engine can do.
And then came 1984, and the appearance in Formula One for the first time ever, of the now legendary, and then reigning Formula Three champion, Ayrton Senna.
Unfortunately things did NOT go well for Senna or his Toleman teammate in the first race of the season in Brazil, as BOTH cars retired with blown turbos, a problem that has always held the team back from the beginning, Senna after just 8 laps, his teammade Cecotto 10 laps later. Senna was pissed off, everyone was pissed off, but they had a solution, and rather than write it myself, here's it straight from one of the team...
In yet another fantastic example of "Most famous names sure as fuck don't mean the best stuff", they fucked off the Garrett turbos that had held them back all these years, and went to the Holset turbos that they only really knew about due to their sponsor using them on their trucks.
Holset knocked them up some suitable spec turbos in FOUR DAYS (More proof, if you need it, that the BS about 'truck turbos' not being made of the right materials for cars is bollocks- You think they magically fashioned them some stronger custom stuff in 4 days? Not possible. They were 100% off the shelf Holset parts), and lo and behold suddenly Toleman's unreliable turbo days were over.
In fact, from what I understand, the one time a turbo did blow (unsure if it was 84 or 85), once inspected it turned out it was because a bit of valve seat (supposedly a weak point on these engines) went through it.
These 1984 Holset boosted engines made 800bhp at 4bar boost, pretty insane for a 1.5ltr 4cyl engine, and while only about 50bhp down over the top cars at race boost, they were still around 200bhp down on the top cars at qualifying boost, simply as they didn't have the budget for special grenade-spec qualifying engines like some top teams did. Aside from that though, if it was BHP per £££ spent, they would've been the top by miles.
These engines were 6.7:1 compression and revved to 11,000rpm in 1984.
The actual Holset turbo used I'm unsure, but looking at pics, especially the compressor side and the compressor back plate, it looks to be a HX50 of some description.
Unfortunately, despite the engine finally showing it's full potential in 1984, with 3 podium finishes for Senna, the following season didn't go well.
While the engine was no longer an issue, Senna left for Lotus, and as the Toleman team had a habit of pissing off tyre manufacturers, first Goodyear, then Pirelli, meant they could only use Michelin, which massively backfired when Michelin withdrew from F1 after 1984 too, leaving them with no tyres at all for the start 1985.
They missed the first three races due to having no tyres, and by the end of 1985 Benetton fully took over the team, which then became the works Renault team, and that was the end of the badass little Hart 415T engine.
The last thing worth mentioning is the majority of the modern pics in this feature have been taken at Geoff Page Racing, who is pretty much the god of Group B and Formula 1 turbo engines, and looks after pretty much every legendary car from that era you can think of. I'd love to go there and do a feature on the place, as there a whole crapload I've yet to learn no doubt, but as yet it's never happened.
Christ, if I could go back in time (this time armed with a decent camera) to about 2000-2001 when Joe Stevens from Bluesprint built my Cossie engine, I'd be able to show you some amazing F1 Turbo stuff- That place, both the actual workshop and warehouse, was full of BMW/Hart/Zakspeed/etc F1 turbo engines, manifolds, wastegates, all sorts, it was pretty incredible.
Anyhow, that's all I know, I wish I knew more, but it's a pretty amazing story considering how much of a (in F1 terms) shoestring budget they were on!
Hi, I'm Stav...
You may or may not have heard of me, but I've spent the last 15 years working full-time in the tuning scene, and the last decade or so writing for various car magazines.