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...
This is the never ending myth that comes up almost every time someone asks about fitting big intercoolers on forums and so on. You can be assured a knowitall, who no doubt has zero experience of it or he'd not say it in the first place, will tell you long boost pipes and/or massive intercoolers will make your car laggy, especially if you have a small turbo.
Well, let me say, that's TOTAL BOLLOCKS.
In THEORY, and it is fucking basic, primary school, narrow minded, short sighted, theory, the longer the boost pipes, and the bigger the intercooler, the longer it takes the 'boost' to travel from the turbo to the engine, and the longer it takes the 'boost' to pressurise it all before it pressurised the engine.
In REALITY, airflow out the turbo travels at fucking HUNDREDS of miles per hour, and airflow in to the engine consists of HUNDREDS of litres per fucking second, so how in God's name do you really think adding even 10ft and 10litres (and that's massively unlikely) to the pre-throttle intake length/volume will make a car laggy is beyond me.
In reality, and I've tried it over the years with really bloody extreme examples, with poxy little turbos and ridiculously big intercoolers and pipe lengths, it never ever feels 'laggier' or 'less responsive' or 'slower boosting' or any other way people want to say it, and usually (Imprezas are a great example as they have insanely long intercooler pipe lengths and massive front mounts) they actually are noticeably MORE responsive and have MORE low down power than before, as low intake temps are far more effective for performance increases than any theoretical response improvements.
Almost all top mount setups, and most v-mount setups too, usually have pretty horrendous inlet temps compared to a decent front mount, and with no real response improvements, giving up lower inlet temps just to shorten boost piping is a terrible plan in reality, which brings me neatly on to this car...
What we have here is an MR2, with a mid mounted 2ltr (2.1 maybe, can't remember and it doesn't matter) 4cyl engine. But the turbo is REAR mounted, a good couple of feet from the engine. That alone is enough to make Pistonheads forum nobheads cry 'LAAAAAAG' in some dweeby middle class voice. BUT hang on, where's the intercooler? Well, it's at the FRONT! Yes, this mid engine car, with a rear mount turbo, has a front mounted intercooler, and at least twenty foot of boost pipes connecting it all up!
Seriously, I've literally NO doubt if this car was created by some random lad in this day and age, not only would it get fucking slaughtered on whatever forum he made the mistake of posting it on, but it'd end up going viral on Facebook etc etc as the hordes of internet 'experts' ripped the absolute shit out of it for being a ridiculous stupid idea, despite none of them having any experience at all with anything even close to it.
I can picture the unfunny memes about it now...
I'm sure, even now, even after everything I've wrote, a lot of people are looking at the pics above and thinking "Fuck me, that must be horribly laggy and useless".
Well, no, no it's not, in fact the above car won the GT300 JGTC (Ie Japanese Touring/GT championship) in 1999, vs RX7s, S15 Silvias, Porsche 911s, Imprezas, and more.
I'm not 100% as I've not found enough detail to be sure, but the same setup in different livery might have won the 1998 championship too (MR2s with the same drivers did), and I think the 2002 GT300 winning MR-S (below) looks like it might've been a similar setup too, but can't find enough pics to be 100% sure...
I actually wrote this for Banzai Magazine last year, but it's still very, VERY relevant, so I'm gonna put it here too...
You know what makes me cringe in the car scene at the moment? Well, a lot of things actually, but at this very moment, as I write this, it's certain peoples obsession, no, expectation, of sponsorship for their cars.
Some people seem to think being sponsored and blagging free stuff is a main goal for their project, in fact many see it as a expectation, and they deserve it just because they've got a nice car. Well let me tell you, sponsorship isn't like that, it's not a charity, it's a two way thing, and unless they get their money's worth out of you, they're either not going to give you sponsorship in the first place, or you'll ruin it for everyone else by short-changing them; putting them off doing so in the future.
While it seems pretty obvious when you think about it, a lot of people don't 'get' the concept of car sponsorship, so let me spell it out for you. First of all, it's not a charity, it's not like asking your Gran to sponsor you for a charity bike ride, there's no “Tuners In Need” fundraising events, and it's certainly not some free stuff you automatically get by having, or indeed thinking you have, a cool car.
Car sponsorship is simply exchanging goods, services, or maybe even money, for advertising, and a big problem is people seem to grossly overestimate the advertising value of their cars. Sticking a few stickers on a car almost nobody sees isn't value for money advertising unless you've been sponsored to the tune of 50p. Competing in some race or drift championship, or going to a lot of car shows doesn't automatically make you a media darling either; like it or not, 90% of competition or show cars are almost never stand out from the crowd enough to get serious amounts of coverage.
Fact is, unless your car is truly special, and by that I don't just mean a nice car that's popular in your local area or club, but truly something stand-out and world-class that has a serious following, it's unlikely it can justify any serious amount of sponsorship over a company simply spending the equivalent amount of money on conventional advertising.
Unfortunately this sponsorship craze has become such a big deal to some that it's become a badge of honour, to the extent that some will happily plaster their cars in company logos in exchange for 5% off an exhaust and a free T-shirt, but in reality they mostly want 'sponsorship' so they can try and show off about being a big shot sponsored car/driver to anyone who will listen.
If people spent more time truly working out how to make a good car, rather than mass emailing badly written begging letters to companies for undeserved sponsorship, the tuning world really would be a better place; especially as so many 'sponsored' cars are far from as good as they could be, as instead they're just a clothes horse for a companies products, no matter how unsuitable they are...
The title says it all really, and that's not opinion, that's cold, hard, fact.
They're not useless, in fact they're a handy guide if you have them, but the only tell a tiny part of the story when it comes to how useful a turbo is. For this reason, basing your turbo choice on what you see on a compressor map is ridiculous, and just shows that you, despite no doubt feeling smug that you understand how to read a compressor map, also shows you don't really know how engine tuning works...
I've actually seen a whoooole lot of people choose not to buy a turbo because there's no compressor map publicly available (or just doesn't exist). And considering pretty much no aftermarket turbo has a map available, and not even all OEMs publish theirs, this is pretty ridiculous.
The fact that the vast majority of the fastest and most powerful tuned turbo engines on this planet runs turbos with no compressor maps available for them is a hint at how "Think they're clever but in fact are stupid" (what's a good term for that, barring dickhead?) so many people are.
So what are compressor maps good for? Well, lots of things. They tell you the maximum (roughly, it's not gospel, most can do a bit more) airflow of a compressor. They tell you the maximum (roughly again, most can do more) pressure they can achieve. They also show you what sort of pressure and boost they're most efficient at, though if you're aiming for the most efficient point you'll be giving up both spool and power compared to a different spec turbo, which is a bit daft.
As the above sounds useful, why am I saying they're not that important? Well, while it's not as accurate as a compressor map, compressor wheel inducer and exducer sizes are a fairly good indicator of these things too. How much a compressor will flow is indicated by how big the inducer diameter is, and how much pressure it's happy to push is generally indicated by a bigger exducer diameter compared to inducer.
The another big reason you can't rely on them is because, as mentioned, the vast majority of the worlds best turbos simply don't have compressor maps available (Only some Garrett, some BorgWarner, and very very few from others), so you'd be likely hugely missing out on the best turbo for you if you went purely by maps.
Also, and this is a biggie, thanks to the wonders of the internet, plus the experts who create and sell these turbos, you're hugely unlikely to be venturing in to uncharted waters by using a turbo, and a bit of research can almost always find out how much they flow, how much boost they can produce, even without seeing any hint of a compressor map.
And this brings me on to the main reason Compressor maps aren't that important- ALL they show is the compressor side, HALF the turbo, and on most applications the less important side...
Compressor maps don't show, in any way, shape, or form, the number one question for 99% of people- How a turbo SPOOLS. Not only that, but it also doesn't show if the turbine side is far too small for the application; something that's often ignored, but is a HUGE factor on reliability and power.
An overly big turbine side won't spool well, or indeed at all- Compressor size has very little effect on spool.
An overly small turbine side not only can restrict power and usable rpm, but high-pre turbine backpressure causes huge reliability issues that wouldn't happen with a correctly sized turbine- What goes in has to come out! Check out my earlier feature HERE regarding backpressure for more info on this...
So to sum up...
Compressor maps = Useful yes, but vital, hell no.
Choosing a turbo via a compressor map = Stupid, as ignores all the main factors.
THE BMW M54B30 (AKA e46 330) ENGINE- GOOD, BUT WITH A HUGE, ENGINE SMASHING, WALLET DESTROYING, FLAW...
About a year ago I was in the market for a new daily driver and part time drift car, and thanks to E46 BMW prices being absolute rock bottom at the moment, an E46 330i Sport was the winner. The 330i is powered by the 3ltr M54B30 engine, and it was ok, but less revvy than I expected; feeling a bit dead beyond about 6000rpm. That turned out that was because the stock ECU is deliberately holding the engine back, partially closing the electronic throttle at high rpm. A remapped ECU totally wakes it up- Making it pull strongly to 7000rpm+ and feeling like a different, much better performing, engine.
I presumed BMW did this to make the M3 seem much more special, and maybe that's part of it, but there's another reason too- When you rev these things they explode in a fucking massive, engine wrecking, nothing worth salvaging, kind of way. Ever wondered why 325 and 328 engines are cheap and common and 330s cost so much more despite being so similar? It's because most of them are fucking broken!
My engine was running great, totally reliable and great, being both my hard used daily driver and used on drift days all over the UK with no problem. Then one day, at 6700rpm in 5th gear, the oil light came on, and stayed on, and it sounded like a bag of nails. I knew this meant game over for the engine, and seemed likely the oil pump failed. But I didn't know why. Well, it turns out it's because of this...
You know what that is? That's the nut that holds the oil pump pulley on! It turns out it's a VERY well known problem with 330i engines revved hard on track, and basically the harmonics of the 330i engine shakes it clean off, even though it's reverse threaded. The other, smaller, M54 engines don't suffer from this anywhere near as much; it's mostly a 330i thing.
So what happens? Well, the nut falls off, which then means the chain and pulley falls off, so the oil pump stops, meaning instant zero oil pressure, which as you can imagine, writes an engine off pretty instantly.
If you catch it super quick and at low rpm you'd likely get away with rebuilding the engine with new bearings etc, maybe a crank polish. That's debatable if it's worth doing over buying a good used engine, but mine fell off at 6750rpm and 3 figure speeds, and I likely didn't notice for at least 5 seconds, so it was deffo game over.
I limped it 5 miles home, and then thought 'fuck it, I'm not rebuilding it' so limped it as far as I could to my mates garage 10 miles away. Amazingly, it made it! Well, it got to about 200m away before it expired, and I coasted it the rest of the way.
What was the damage? Well, this...
Ever seen a cam worn down so much you can see inside it? No me neither, but it's pretty cool. That's a hole in the sump from a conrod in the 2nd pic. 3rd pic is the oil pump with the pulley that had fell off. 4th pic is the alternator bracket with a hole in as the conrod went flying through the block and that too. 5th pic is, among other things, a very bent and broken rod. And 6th is the remains of a cam bearing cap after being ran with zero oil for about 15 miles!
So what the hell fuck can you do about it? As it's mega common, and pretty flippin' disastrous lots of people have looked for a solution. There's a few expensive things that 'seem' to fix it, and a few cheaper things that seem to just delay the inevitable...
So, 'fixing' it. Well first up, BMW clearly knew of the problem, in fact to the extent they fitted a different nut to later engines (bottom right) which basically just seems to have thread lock on it. This supposedly helps, as it seems almost any M54B30 you take apart, even low milers in good nick, will have a loose nut, and earlier ones are worse regardless of miles, BUT it will still happen in the end, threadlock or not.
Another 'solution' is lockwiring the nut in place (top left). You can even buy kits for this, but again, it delays it, not fixes it. The entire pulley ends up shearing off.
Next up is almost the same solution and same 'in the end' fail, spot welding the nut in place, as the top right pic shows.
A better solution is a modified pump with a 4 bolt pulley, as per center bottom. Shame it costs about 750quid, which is nearly twice what a used engine costs.
Because it's crank harmonics that cause it, an ATI crank damper (bottom left) supposedly helps too, but again, it's big money, which turns most the appeal of a 330i in the UK (ie they're cheap as chips) down a little.
Best of all, but serious money that would certainly make you wonder why you didn't buy an M3 in the first place, would be a dry sump setup (top centre).
So what have I done on mine? Well, I picked up a low mile engine for £450, got the nut spot welded in place, which deffo isn't the full solution, BUT I hope it lasts a long time. Finally, partly as I wanted one anyhow for performance reasons, and partly as it's entirely possible it will change the damaging harmonics to a different RPM that it's no danger any more (but literally no way to know, it's SWAG- Scientific Wild Ass Guess, but a hopeful one) I've got a super lightweight flywheel to replace the fucking mental heavy dual mass setup they come with.
WILL IT LAST LONG? FUCK KNOWS! But the theory is fairly sound, I'll pray to He-Man that he can help it hold together, and one thing's for sure, I'll have fun until the time when it does happen again, if it happens.
If it does fail, I'll let you know!
The one thing I miss since becoming a freelance writer, is the fact I miss out on the new cars manufacturers send magazines to test. I miss it not because they're amazing cars, as tbf my own cars were usually faster and more fun, but I genuinely do enjoy testing cars, seeing how they really drive, and see if there's the potential to actually make them awesome with a few modifications; especially as most reviews I read sound like someone who's had a 30min jaunt around the streets, sat back down at their computer, and made up a load of cliche filled crap they think the reader will want to hear.
Some cars we were sent disappointed me, in fact most cars did, but some were a surprise, and one of the biggest was the then-new Corsa VXR. I honestly HATED it for the first few hundred miles, and didn't like the Astra VXR I tested before it either, and that was much faster...
While they look pretty decent in press photos (it was a red one, exactly as above), in the flesh it looked much taller and bulkier than expected, and from behind the wheel, despite the badass Recaro seats, it felt like the car and seating position was about a foot too high, which is a huge negative point for driving in my book.
For the first couple hundred miles I still didn't warm to it. Yeah it went well for a standard hot hatch, with decent torque from the turbo, all the VXRs do really, though it also had a very noticeable performance drop with sustained hard use that felt to me like the standard intercooler was heat-soaking.
The main killer of enjoyment was the fact it still felt like I was sitting on the roof due to the seating position and tall thin chassis, which made it feel, well, far worse than any actual timed performance shows it is.
While the car was certainly capable, it didn't stand out at all compared to countless other cars I'd tested, and just like most standard cars, any real fun or feel was sucked up by the fact the manufacturers try to make a refined car that will stop your average Joe from either hating it for being too unrefined, or crashing it.
But I'm not Average Joe, I'm Stupid Stav, so it just felt a let down, too normal- Until I started driving it like a loon that is...
As the miles piled on (I had a lot of shoots to do that week, and I did about 250 miles a day in the thing) my frustration with it feeling a bit numb and crap made me chuck it about far more than it initially felt capable of, and then, well, something just clicked.
It turns out, while still a bit too 'standard' for my liking, was actually bloody good when driven on/over the limit; not at all like it felt when driving at 7/10ths. When driving in maximum attack mode it almost shrank around you, and was in fact incredibly adjustable with both the steering and throttle, to the extent you could get lift-off oversteer at will, and a friend I gave a lift to, after about 10mins of saying nothing and just holding on tight, suddenly goes "So is this thing rear wheel drive then?".
I've never tested a car that look me this long to like it, but once I did like it, I really, really didn't want to give it back, not because it was amazing, but as standard cars go, it had the potential to be one of the most hilarious modern hot hatches there is. Just a few basics, lower seats, lower ride height, better intercooler, and a more audible exhaust, and I felt the car would be the same hilarious fun it was at 11/10ths, but unlike when standard, it'd still be almost as fun at less licence losing, car crashing, speeds.
Funnily enough, a few months later Vauxhall sent us the Corsa VXR 888 edition, which was lower, stiffer, faster, and noisier (to the extent of pretty loud pops and bangs on the over-run), and that pretty much confirmed what I thought it'd be like after driving the standard one; great fun, and stupid enough to not get bored of quickly.
Honestly, if I was in the market for a modern-ish hot hatch to tune (and I'm not), while it's not the 'best' one, not the fastest, for me driving is about fun, and I'd get a Corsa VXR...
If your turbo doesn't work as well as it does for others, you need to face facts, it's probably your fault...
Turbos are amazing things, they're a big reason the vast majority of the worlds fastest cars in almost every discipline are as good as they are, and for us tuning obsessed idiots it means we can go a whole shitload fastest for our money than we could if they didn't exist.
BUT, and this is something a lot of people either underestimate or seem to be totally oblivious to- They're not fucking magic! You can't just throw a turbo at a pile of crap and expect it to work as well as proven results elsewhere, you need to do things properly...
Some people are just plain stupid, and I mean the ones who wonder why they've not instantly got the same 800bhp another engine with the same turbo has, despite the other engine being of a totally different spec, running twice the boost pressure as them, or not even being the same fucking engine. But forgetting people who shouldn't be allowed near a turbo in the first place, it's the smaller, but almost as drastically important changes, that most seem to miss. There are literally hundreds, but this is some of the most common...
PORT MATCHING- Christ, the amount of people I see who copy someone elses turbo and manifold spec, spend well over a grand on some fancy 8Boost/Part-Race tubular job, but just slap them together and think that's going to work great is unreal.
Look at the pics at the top of the page- Just because something has a T2/T3/T4 bolt pattern flange DOES NOT mean the port sizes are the same, in fact they're almost always far, FAR smaller than the manifold ones. And that flippin' massive flat step between the manifold and turbine is a killer for flow, and a good way of buggering up how fast your turbo spools, and if you're anywhere near it's limit, even what peak power is coming out of it.
A lot of BorgWarner 'T4' flange turbos have typical T3 sized ports, so the step is huge, and to be honest even most T3s, especially things like twin scroll Holset ones, the ports are far smaller. It's an OEM thing too, look at the top middle pic, that's a Skyline GT-R turbo, R32, R33, and R34 ones are all like that- T2 flange, but the port only goes 2/3 the way along compared to a typical manifold/gasket, leaving a 5cm by 1cm flat plate for the exhaust gasses to smash in to, causing all kinds of flow destroying turbulence.
Do what do you do? Well, you port match it. You don't have to be an engineering genius, it doesn't need to be perfect, and you certainly don't need to open up the entire port, but if you can use a Dremel, die grinder, even some files, and turn these big flat edges in to smooth transitions from the manifold port size to the turbine port size, you can drastically improve flow and performance.
TWIN SCROLL TURBOS-
Fair play, twin scroll turbo setups can be damn good. A good example of how good they are is a little 2ltr engine with a big Holset HX35 12cm on it. Even using the standard Cosworth YB 2wd exhaust manifold (that big cast iron rusty thing centre bottom of the pics above), which is twin scroll, a HX35 12cm (a big, journal bearing, cast wheel, 600bhp+ proven turbo, not exactly a new design either) is well proven to hit 25psi boost by just 3500rpm. Same results on Mitsubishi 4G63s with twin scroll setups.
Awesome when you consider a single scroll setup with a similar size turbo, even fancy BB core ones with £1500+ price tags, tend to not hit full howl until upwards of 5000rpm- That's a whole different world of drivability.
The thing is, twin scroll manifolds are expensive and relatively uncommon, so a lot of people can't run them, certainly not as easily as they can find badass twin scroll turbos. That's not the end of the world, as while a lot of people ask me if it's possible, I can assure you you can 100% run a twin scroll turbo on a single scroll manifold. Of course it won't spool like a twin scroll setup, but done right it's as good as the single scroll version, so yeah, go for it- Thousands of people do with huge success.
BUT, just like the port matching mentioned earlier, the divider on the turbine inlet flange is a big ol' turbulance creating flat plate when ran on a single scroll manifold- So again, smooth it off rather than just bolting it on.
TBF you really don't need to fully knife edge it like the one pic at the top, that's a whole lot of work and super thin metal is asking for it to break off and take your turbine wheel with it, but massaging it from a flat plate to a nice smooth curve is well worth the 15min work it will take to do.
POXY LITTLE DOWNPIPES-
Just like I explained in THIS feature the other day, the first few feet of exhaust after the turbine wheel is by FAR the most important part, especially for spoolup. Unfortunately people often don't realise this, so fit god awful 2.5in downpipes despite the turbos being 600bhp+ beasts, and then they wonder why their spoolup sucks ball.
Some make the excuse of "Well, the turbo outlet is 2.5in, so why would I need bigger?" Because reasons, that's why. Honestly, it makes a huge difference, even swapping to a big downpipe on a 2ltr engine fitted with little 350bhp turbos can make a big difference to spool, never mind turbos twice the size.
To be honest, to get the best out of a lot of turbos even the standard turbine outlet needs modifying. Good examples of this are most Holset HX35s and HY35s, which have a 2.5in outlet which is cast as part of the housing for the first 4inches or so. People have seen VERY noticeable improvements in spool, over 500rpm, by chopping off the back section and welding a 3-4in v-band right from as close to the turbine wheel as possible.
OIL FEED AND RETURN-
I'll finish this off with a non-performance one, but one I get asked all the time, and that's oil feed and return sizes.
I've lost count of the times I've seen people buy a brand new turbo, fit it, it smokes its tits off, and they remove it crying that it's broken already and it's completely shit. No mate, it's you that's shit.
Of course some turbos are faulty and oil is pissing past the seals through no fault of your own, but that's pretty rare as the oil seals are a design that just don't wear or break easily.
90% of the time it's because whoever has fitted it has fitted too big a feed, or most commonly, a comedy small oil return.
"Oh I fitted a dash12 billet anodised alloy amazing one I found on eBay, it must be fine" they say. Until you ask how big the internal diameter is. And they don't know. And then they look, and it's 10mm or something, hence the oil can't get out fast enough, and it's forced past the bearings instead. The fact is, oil returns need to be BIG to work well, most turbo manufacturers specify 19mm internal diameter minimum, and changing a little pipe to a big one usually stops the smoke. So bin the fancy looking but restrictive aero fitting and just use a normal but big metal and rubber return line that actually works properly- It's not as if anyone can see it anyhow...
Oil feed is similar, but a bit more complicated- Too big and you can get oil flooding past the seals again, but too small and you'll starve it of oil and kill the bearings in no time. Why it's complex is all turbos are different and engines have wildly differing oil pressures.
Almost all manufacturers state a maximum oil pressure, but as this is measured at the turbo inlet, almost nobody checks this, so just guess- often wrongly.
A rule of thumb I tend to have luck with is non-BB turbos use a -3 line with no restrictor, the more common -4 can be too much for some, which leads people to use restrictors, and they they fit one way too small and run the bearings dry. Then cry a lot and blame the turbo even though it's their fault 100%.
BB turbos always in my experience have manufacturer recommendation on oil feed and restrictor size, so that's rarely an issue unless you can't read.
But most of all- Make sure the bloody oil return is big enough, has no kinks, and ends above the sump oil level. A great flowing oil return can usually counteract a slightly overkill oil feed in my experience...
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.