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...
IF you're going to take influence from something when tuning your own engine, I always say don't just copy other tuned road cars, or even tuners demo cars, as they're usually massively flawed, no matter how quick and expensive- Take influence from race cars. When I mean race cars I don't mean just some random persons race car, I mean world class, best there is, race cars. They've got the best budgets, and the best people, so if they're doing something, and it's not JUST because the rules say so, it's fair to say it's good, and it's strong.
The problem is, most modern stuff is shrouded in secrecy, is heavily restricted by rules and regs, or is so out there that it's just not relatable to our own tuned cars.
So what do you do? Well I go back in time a bit. While electronics and so on have improved, the basic principles of tuning are still the same as the 80s, and 90s, in fact there's a lot of stuff from the 70s that's fucking genius compared to what we think of 'top' tuned engines these days, 40 odd years later.
This is still a big issue, as a lot of old race technology was just as secret back then, so nobody ever knew, and by the time it wasn't such a secret everyone had forgotten about it, so the true details are next to impossible to find on paper, but luckily, we have EYES and the internet has PICTURES, and those my friends, are able to put words in our brains, we call them thoughts and ideas and plans.
As any of you who've read my shiz before probably know, I love turbos, and boost, and anti-lag, and frankly anything to do with turbos, and for that reason, despite there being not much legit detail about them, and having zero interest in later N/A ones, I LOVE the Formula One Turbo engines of the late 70s and early 80s.
These engines were totally ground breaking, "inventing" and using many turbocharging methods that are even today only ever used in "Groundbreaking" turbocharged cars, well over thirty years later, and many that were used would be slated in a "WTF, that won't work" way by the typical internet bedroom tuners of today if they saw someones project car with it on, despite it being technology twice as old as some of these dickheads are.
ANYHOW, because of this, I've decided to do occasional features on certain mental turbo race car engines from back in the day (F1, GroupB, Rallycross, IMSA, and so on), as they are often VERY relevant to today's tuning, the info out there is practically zero, and frankly, they're cool as fuck.
What this WILL be though is me explaining what I see via pics etc, as almost none of the stuff I'll talk about is mentioned anywhere on these old F1 pages with engine details etc, which is a shame, as these mental engines are never done any justice due to this- They just talk about power and boost and that's it.
The one I'm going to start with certainly isn't the most famous or sucessful, but it's one of the most oddball, coolest, and most changed over the years, the Ferrari twin turbo V6 from the 126 series of F1 cars...
Right from the start of it's life in 1981, it was a 1496cc 24V V6, which had a tiny stroke of just 48mm. That's really small as these things were built to REV and make POWER rather than potter around at low rpm- A typical production 1.4-1.6ltr engine tends to have a stroke somewhere between 75 and 90mm.
Compression Ratio was LOW, about 6.5:1, despite running the most det-resistant fuels known to man, plus water injection, massive intercoolers, and more, and for a good reason too- to get BIG bhp per litre you need BOOST- These ran, at their peak, over 3bar (~45psi) in race trim (~660bhp), and over 4bar (~60psi) for batshit crazy qualifying 850bhp mode.
This is the equivalent of a 2ltr engine pushing out over 1100bhp (qualifying) or 880bhp (race trim), and to lasting not just a couple of hard laps, a quick squirt up the street, or 8seconds up a drag strip, which is enough for most tuned road cars today to crap their pants, but 1.5 to 2 hours fucking flat out pedal to the metal full revs full boost full anti-lag racing. People can argue about this all day long, but you think even with modern ECUs and sensors you'll easily get an engine with that much bhp/litre lasting 2hr flat to the mat at 9.5/10.5/11.5:1? I don't. A lot of mappers can't keep engines together running 1.5bar and 8.5:1...
Anyhow, on to the cool shit you can see in pics...
First up, as above, at first the thing wasn't even turbocharged! It was "Sort of" supercharged, and what I mean by "Sort of" is it ran a Brown Boveri Comprex Pressure Wave supercharger. Those things are very odd, like a mix between a turbo and a supercharger, but in fact neither. They're rare, and a bit flawed, but very cool. The Wikipedia page about them is HERE. It was only tested like this, in 1981, and never raced, as you know what's better? TURBOS!
Despite the big deal about a few modern BMW and Mercedes Vee engines with the exhausts inside the Vee and the inlets on the outside, it's far from new, and this Ferrari engine ran like this, as the pic of a very early version above shows.
Twin KKK K26 (Possibly K27 compressor side) turbos, and a single, but fucking massive, external wastegate.
Note the pre-turbo throttles, which was a very early way of helping combat turbo lag (put your hand over the vacuum cleaner inlet and listen to the rpm increase, same thing...).
Also note the inlet plenum design, which is basic, but done in this cone shape as a way to equalise airflow- The furthest away cylinders get the MOST air in a boosted application, which is another reason all these aftermarket 'high flow' box/blob inlet plenums are shite.
Another pic from a fairly early version show the less then sexy, but clearly fine, air filters, but most interestingly, how the wastegate is pushed open- Not by boost pressure like 99% are these days, but by EXHAUST BACKPRESSURE!
(follow the pipe from the bottom port of the wastegate to the turbine housing inlet)
This is actually VERY clever, as pre-turbine backpressure is key to power and reliability, more so even in my eyes than the pressure everyone knows, boost pressure.
As the pic below shows, the wastegate was piped up in the usual twin port way, with a typical vac line going to the top feeding it boost, allowing boost pressure levels to be controlled easier. Also note, below pic is later spec with full EFI.
Next up on the "Blimey, how interesting" list, the intercooler inlets and outlets...
The pic above in an early engine, but the design stayed the same regardless, simple as it's a good idea, and that's equal flow inlet and outlet designs for the (massive) intercoolers. 99% of intercoolers you see have a 3in (or less) round inlet and outlet pipe, but that isn't making the most of the intercooler at all, in fact a lot of the size is wasted. Having it as above makes sure the airflow is spread right across, massively improving cooling for any given size cooler. (also note, yet another different inlet plenum, but still smaller at the far end).
Look at the bottom right of this late spec version of the engine at the inlet plenum design. This is the "Twin Plenum" or "Equal Flow Plenum" style, used by Audi since the Group B days right through to modern LeMans etc cars, and often seen in Rallycross, WRC, and some tuned road cars. A quick google will find you pictures of the internals, but it basically directs air through a long but narrow slot the length of the main plenum, which gives far, far, more equal flow per cylinder than a traditional inlet on a boosted engine.
The more equal airflow per cyl, the easier a car is to tune for maximum reliability as well as power, and overall makes for a more efficient engine too. A BIG reason a whole lot of tuned turbo road cars blow up is because the AFR sensor signal they tend to be tuned from is an average from all the cylinders, but some cylinders get a LOT more airflow than others due to the unequal flow, so some run much leaner and much hotter than others, so while the average AFR might be 11.5, some might be 10.5, some might be 13+, so those lean cylinders pop head gaskets and melt pistons...
YET AGAIN, the above is something pretty ignored in the tuning world, esp in the UK, and when me and Zurawski Motorsport designed one for my RB20 engine, I got no end of shit, fucking pages and pages of it, from internet tuning experts (ie never built a good car in their life) telling me the design is shit, won't work, restrictive, etc etc, totally oblivious to the fact it'd been used on some of the worlds best engines for the last 30+ years.
Lo and behold my engine spooled amazingly well for the turbo size, made fucking mega power for a RB20 of that spec, and most importantly, was stupidly, hugely, det-resistant compared to most- Even 2bar on pump fuel there was no sign of it...
Next up, my favourite turbo thing in the whole world, and something rarely ever mentioned until cars of the 1990s, ANTI-LAG! I've never seen any info on it, but the pics clearly show it...
The type of anti-lag (ALS) used wasn't the basic throttle bypass ALS used on tuned road cars, most 90s rally cars, and still very popular in rallycross, but the better, albeit more complex version where the air goes directly from compressor outlet to turbine inlet, as per WRC cars and other current high-end turbo racers, the later versions of the legendary Audi Group B car, plus late Celica GT4 rally cars, and later Mitsubishi Evo rally cars.
Amazingly, and I'm still not 100% how it was done, but even on early mechanically fuel injected engines (as above) it was used. The above engines aren't the only mechanically injected F1 Turbo engines that ran it (See upcoming features), but from what I've guestimated from the pics, the increased fueling needed when the ALS was operational even with mechanical injection (rather than EFI, where the ECU has control over the injectors) was done via Hobbs switches and other basic sensors.
You may be thinking "What the fuck on the above pic hints at anti-lag anyhow?" well, that's the T-piece just after the compressor outlet with the green hose on it that disappears under the air filters. Logically that can only be for 2 things, a dump valve, or the above form of ALS. I was 100% sure they didn't run dump valves, but still, I'd like to see more pics before I was sure it was for the ALS. Luckily, there's this pic...
While the mechanics are busy swapping turbos, you can once again see the green pipe, but most importantly, notice one exhaust pipe running forwards, between the compressor housings, to what looks like a clamp, then a valve. That is 101% only one thing, the ALS valve, that lets the fresh air from the compressor outlets in to the exhaust pre-turbine.
EDIT- In fact, to double confirm it, I found this pic too last night, fairly clearly showing the ALS valve between the two turbo inlet trumpets...
The above picture shows a late spec engine showing a good view of most of what we've talked about. The equal flow inlet plenums, the equal flow intercooler pipework, the anti-lag outlet pipe, and also note, as this is a late spec engine, it's running EFI with 2 injectors per cylinder.
Also, look at the temperature sensor stickers, measuring not only compressor outlet temp, but temp at each inlet port, showing not only how good the intercooler is, but will help indicate how equal the flow is too.
Intercooler is made by Behr, who are about the best intercooler makers in the world, and made the standard Sierra Cosworth intercoolers too, which are amazingly good for their size too.
On a related note, the ECU setups on these were Weber Marelli ones with Bosch injectors, just like Cosworths, Integrales, Ferrari F40s, and many other legendary 80s and 90s turbo cars.
Finally for above, can you spot something else different from earlier engines?
Yep, late engines seem to have a different head design, with 2 exhaust ports per cylinder, ie one per valve. Some, albeit not many, road car engines have this, such as the 1.9ltr 16V engine found in the Peugeot 405 Mi-16.
Anyhow, that's about it for this time. Hope it's not just me that finds these fucking mental old engines really interesting. I really do hope it's not just me, as if more people took their design influence from these there'd be a whole lot cooler and faster cars out there in 2016...
PS- Here's a couple more random pics of this mental (albeit nowhere near the best F1 Turbo engine of its era) motor...
RWhen it comes to modifications of turbocharged engines, one of the first things that come to mind with a lot of people are blow off valves, or dump valves, depending what you like to call them (same thing!).
They've been around since at least the 1970s on race cars (though pretty much disappeared on turbocharged works race cars after the early/mid 90s...), factory fit parts on most turbocharged petrol engines from the mid 80s onwards, and from around the mid-90s onwards aftermarket ones became THE thing to have- It was, and to some extent still is, the first engine mod people do to a turbo car.
But what DO they do? What are they REALLY for? Well this is where the confusion/bullshit comes in, not only thanks to the internet, but thanks to the fact most the things said about them to sell them, in the past at least, were lies too.
Christ, the "Blowoff Valve" Wikipedia page even talks total and utter shit about what they do, and why, and how, and whatnot...
THINGS THAT PEOPLE SAY DUMP VALVES DO...
"Reduce turbo lag"
No. They increase it if anything. Turbo shaft speed drops far more with a BOV fitted than without. That's their true purpose, to prevent surge and overspeeding when you shut the throttle. Honestly, anyone with a turbo speed sensor will have seen this, and I've done tests with timing equipment a few times now, that shows, even if it's not noticeable seat of the pants, it makes it worse, not better. This IS fractional though, don't expect a big, or even noticeable difference on most engines- Really depends on the application.
"Prevent your compressor wheel from slowing/stalling (or going backwards)"
No, they actually SLOW a turbo down, that's their actual job, they're a safety thing, to prevent overspeed and surge on a closed throttle, which in some extreme situations can damage the turbo. Honestly, watch a turbo with a turbo speed sensor fitted, the RPM drops far far more with a BOV than without. The 'spinning backward' thing people say is fucking retarded btw.
It's the AIRFLOW that stalls, not the turbo, something I'll explain further down...
"Help prevent compressor surge"
Yep, they do this, but only off-throttle compressor surge, which isn't that damaging or sustained to turbos, as there's no load on the turbine off-throttle. It's on-throttle surge that can be hugely damaging, and it does nothing to help that. "Certain" turbo manufacturers and their badly mis-matched compressor/turbine combos are the main cause of on-throttle surge...
"Help stop turbo damage due to (whatever)"
Well yes, this is the real reason they're fitted, and can be useful for this, but their need is often hugely over-stated, and how they help prevent it is ass-backwards too. The usual bullshit myth is they help prevent turbos stalling, and the sudden slowing of the turbo is what damages them. NO. They help SLOW the turbo, as without them turbos can overspeed when the throttle is shut, and surge all over the shop, and in certain applications that can damage the turbo.
"Help MAF sensor equipped cars run right (recirc ones ONLY)"
While it's indeed true many engines with MAF sensors run like shit off-throttle if you fit a vent to atmo dump valve, the common info that you HAVE to run a recirc with a MAF is bollocks too in everything I've ever experienced.
Running no BOVs at all is absolutely fine almost always.
It's possible there's a car where the MAF sensor does shit itself, but so far I've not found it. I've heard a whole lot of rumours, I was told by countless people without a shadow of a doubt it'd cause the 2.7TT (ie S4) Audi engine to run like shit and so on if removed, but I tried it, and it's fine- Turned out, as ever, none of these people had ever tried, just 'heard' it did.
EDIT- Now I think back, I do recall a time when it made the MAF go crazy for a second, but that was a BIG aftermarket turbo on BIG boost on a small engine, and that was the only time it happened. Generally, no issue at all.
"Makes that cool chatter noise"
I know most of you know better, but it's rare to see a video of a car with decent turbo chatter without at least one comment saying it's the BOV making that noise, or asking what BOV it is as they want one that makes that noise.
IT'S NOT! HAVING NO BOV AT ALL IS WHAT HELPS MAKES THE NOISE!
Fuck, when I was 18 (1998!) even I at first thought the same, as MAGAZINES TOLD ME SO. In fact these "expert magazines" told me that it was HKS SQV valves did that noise, and though they were about £350 back then, and I wanted that noise SO BAD I would've paid that.
In fact, after a tuned MR2 Turbo came past and chattered like fuck one day I rang Torque Developments (they were the only HKS dealer back then) to order one. THANKFULLY, the sales persons tone of voice and choice of words made me very suspicious, while also accidentally giving me some hints that helped me research what REALLY made the noise (No internet back then!), so I thankfully didn't get skanked out of £350...
THINGS DUMP VALVES DO THAT PEOPLE DON'T TALK ABOUT...
"Help suppress noise"
The main reason they're fitted to OEM vehicles is as noise suppression devices, in fact that's the exact name they're given in many official workshop manuals. The noise I mean is turbo chatter, which is a lot harder to silence with an airbox than the ptschhh of a dump valve. We might like chatter noises and induction noises, but your average Joe new car buyer doesn't. In fact back in the day I worked at a dealership and an Impreza STi we had in on a P/X that we then sold was returned to us by the customer due to "Funny noises" it was making, as it had slight chatter as it had an induction kit on it.
"Help slow the car when in limp home mode"
A lot of new cars also use a system that holds the BOV(s) open, preventing boost/power being made in case of an issue that puts the car in limp home mode. Useful as an OEM.
"Leak like bastards, causing underboosting and turbo wear"
I know they're not meant to do this, but this is a major and common issue, and often impossible to detect unless looking for it. A dump valve is another potential leak point, and split diaphragms and/or weak springs means they leak surprisingly often, especially OEM and cheapo ones, and even if your turbo is still making full boost, a leak can cause a slower boost rise, and a turbo (and therefore entire engine) working far harder.
Confused? Don't be. I'll clear your mind (a little) in this next bit...
""SO! I was always led to believe that turbos stall with no BOV, and now you're telling me turbos SPEED UP?
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.