First up, if you've not seen Part One of this feature on some of the maddest tuned cars you're likely to clap your eyes on this year, you better click HERE to check it out...

Now that's sorted, no need for an intro, lets get right on with showing you the rest of these flippin' bonkers cars. 

First up, a car you may have seen a video of on the Stav-Tech Facebook page, a 9second, front wheel drive, turbo, rotary engine, LADA. Yes, a flippin' Lada. This is Russia afterall...

This is what we'd call a Lada 110, though in Russia it's a VAZ 2110, a front drive car produced from the mid 90s until late 00s in Russia, and actually has some performance history, having the aerodynamics jointly designed by Porsche, and competed in the World Touring Car Championship (WTCC) in 2008 and 2009.

Anyhow, while 99% of the world don't realise it, Mazda aren't the only rotary engine makers of modern times, VAZ do. In fact these days VAZ do it a whole lot more than Mazda, for a wide variety of vehicles too, albeit in VERY limited numbers; and the above VAZ/Lada is one of them.
The VAZ rotaries aren't the same as a Mazda 13B, but they are the same capacity, but work very well, and have been adapted for lots more applications, inc front wheel drive...

There you have it, a 1308cc twin rotor engine, transversely mounted and front drive, running 2x Tial wastegates, a Garrett GTX42 with a Tial v-band manifold, and dry sump by the looks of it. Mental. 

While the 9.9sec quarters were done on the old engine it seems, and now it's got a new engine, though no new times yet...

A bloody Lada THREE ROTOR! It's running a Garrett GTX55 too, so likely to be, well, lots! 1500odd, as they're good for over 1600bhp. 
Going by the pic, the engine is dry sump and almost deffo running on methanol as no intercooler, but most interestingly, look at the different design compared to a Mazda rotary- Peripheral exhaust ports on top, one per cylinder, but the inlet ports are below, and seems to be 6 of them, so they're either conventional side ports, or twin peripheral ones? Who knows. I also wonder if this engine is mounted upside down? It's dry sump so it's possible on a rotary.

Anyhow, let's look at something else. Or is it? Might be the same car in an earlier form...?

10.4sec, front drive, 3 rotor Lada, but NON-TURBO this time!

Right, on to something slightly more normal...

An Impreza, that runs low 8s, and has a GT42 turbo hanging out the front of the car!

How about everyone's fave FWD drag car, a Honda Civic...

Nothing to unconventional, but it's VERY fast, 9.7 1/4, which considering the barely prepped surfaces of Russian drag strips, that's properly moving.
And how does it go that quick? Well...

A Honda B18 lump and most importantly. a big fuckoff Holset HX55! For massive turbos they really do spool well, and obv' no issue on this one, despite that being a 25cm housing by the looks of it, ie one of the bigger ones. A true 1000bhp capable turbo.

You know what's even faster though? A fucking massive Jeep Cherokee! 

Fuck knows why it's even a 'thing', but there's a good few mental Jeeps in Russia running 9sec quarters! This particular one runs 9.5 and is powered by a 7ltr turbo V8.

You know what's even faster than both of these things? Another fucking Lada!

Probably the most badass looking Lada you'll ever likely see, this runs 9.1sec quarters despite being FWD, and has a rather unusual engine and box combo...

You might recognise the engine as it's the good old Vauxhall C20XE lump, running a massive GT4202 turbo, and nitrous as well.
Most interesting, the gearbox is a modified Mitsubishi Evo4 box, running FWD only.

You know what's even faster than a C20XE Lada? A Mitsubishi Lancer Evo3, but oddly, it has an engine swap!

Looks like a normal Evo3, and indeed the standard 4G63 engine can produce some ridiculous power, well over 1000bhp, but this car is doing something a little different to get it's 8.9sec quarter miles...

It's the 3ltr V6 normally found in Mitsubishi GTOs and 3000GTs, but running a BIG single turbo and nitrous too. Nice.

Last but DEFFO not least, what's faster than an 8sec Evo3? Well an 8sec Audi S2!

Looks pretty normal from the back, though clearly means business, but the front view is a little less subtle...

Looks like the body is all carbon, and runs 8.8sec quarter miles thanks to, well, check it out...

That's the legendary 5cyl 20V Audi Lump, packing a flippin huge turbo, at least GT55 size by looks of it, maybe GT60 in fact, and likely running the amazingly strong Audi 4wd system too, maybe even a stock S4 box as so many crazy power ones do. Here's another angle of the engine...

The internet is a wonderful thing, it's made this world WAY smaller, and has shown us things, just by searching for them with Google, that we'd either never see otherwise, or at best only see if we were lucky enough to find that a magazine had hunted these things down.

It's not PERFECT though, as while it's not hard to search for stuff from English speaking countries, it's fucking tricky if the country doesn't speak English, and it's nigh on impossible if the alphabet they use isn't even close to what our is- You can't easily Google words that use letters your keyboard don't even have!

Granted, Japan is well covered despite the language and alphabet barrier, partly as they use a lot of English words in their tuning, and partly as the Japanese car scene is world famous, but even from Japan there's a whole lot we don't see unless someone who can speak the language tracks it down and share it.

But other places, less famous places? Well, there's very little to be found, if anything.

I mean, Russia, do you know much about the tuning scene in Russia? I've seen a few things, but nothing much; mostly drift cars. Due to the lack of press it gets you'd think the scene is pretty small and the cars are mostly quite tame, but no, fuck no, their drag cars for example, front, rear, and 4wd, are fucking MENTAL, and that's what this feature is all about.

I can't speak Russian, or read Russian, or anything close, so I don't know all the info, but prepare to mutter "What the fuuuuck" to yourself a great many times, as we take a look at some Russian drag cars...

Well, it's a Mitsubishi Eclipse, the car made famous by Fast And The Furious, and a pretty badass looking one too, and the air filter sticking out the headlamp kinda indicates it means business, but what's under the bonnet? 
Well, some of these have Evo 4G63 turbo engines and 4wd as standard, so you'd imagine this has a big power one of these, right? Well... "What. The. FUCK" moment coming up...

It's a muthafuckin' 2JZ! Fitted transversely and powering the front wheels! I dunno about you, but I've never seen a transversely mounted 2JZ in my life. It fits amazingly well, and shit, it's a properly mental spec one too...

Badass long runner tubular manifold, huge custom inlet, big coils, huge turbo, dry sump by the looks of it too, and so far it's ran a 9.1sec quarter, and, well, it's got 1127bhp!

Next up, an MR2 Turbo. No engine swap this time, the original 3S-GTE heavily tuned this time, but it runs 9.7sec quarters and pulls some fucking massive wheelies...

They love Japanese cars in Russia, but Russia is the home of Lada, so there's a lot of them too, but nothing like what we're used to here...

This Lada runs 9.1sec quarters thanks to a big power 1.5JZ engine under the bonnet!

It's not the only JZ Lada either, this one runs 9.3s...

Maybe it's a stereotype, but it's easy to imagine Russian tuned cars as awful looking DIY jobs, and indeed some are, but even these are bloody fast. This old Prelude looks ridiculous, serious DIY fibreglass bodywork going on, but it's powered by a naturally aspirated Honda B-series engine and STILL runs 11.1sec quarters!

While we're on the awful looking DIY lightweight bodywork theme, check this out. A FWD Lada, still running a Lada engine, albeit turbocharged, but runs 10.7s!

Anyone who's been in to the Japanese car scene for a long time will remember in the early 2000s the Skyline GT-R drag racing scene was HUGE in Japan, with tons of dedicated and ridiculously fast R32 and R33 GT-Rs, but most seem to have disappeared, not seen for many, many years.
Ever wondered where they all are? Well from what I've seen, they're all in Russia! There's countless 8sec Skyline GT-Rs in Russia, not to mention absolutely tons of them in the 9s- Soo many I'm not going to show them in this feature. But they've got them in the 7s too...

This R32 is the fastest of them all, running 7.4sec quarters via a Powerglide gearbox, but while the others are RB powered, this one isn't...

Yep, that's a Nissan GT-R VR38DETT lump, but running two BIG turbos, and well over 2000bhp if my shonky Russian translation is accurate.

The second fastest R32 GT-R is only 0.1 of a second slower mind, and IS RB powered...

7.5sec quarter mile from a flippin' badass looking R32 GT-R with a mega RB30 lump...

Another red RB30 engine'd one is only slightly slower, at a still crazy 8.1sec, and while it just looks like a red R32, it's got 1200bhp, the exhaust manifold is pretty funky and puts the turbo by the headlamp, and it's got early RB20 cam covers, which always look good...

Last of the Skylines I'm going to mention is this R33 GT-R, again running a ridiculous 8.2second quarter mile, with a similar exhaust manifold to the one above...

Skylines aren't the only 4wd straight six turbo Japanese cars running low 8s in Russia. This 1500bhp 2JZ Soarer runs 8.2s. "Hang on 4wd Soarer?!" Yep, fucking 4wd!

They seem to have a thing in Russia about converted normally RWD Toyotas to 4WD with GREAT effect, as well, here's a Supra road car that runs mid 9s and is also 4WD...

Perhaps the most unexpected 4wd Toyota is this one, a big 4 door JZX90 that runs 8.3s...

It actually runs a modified Toyota A340E gearbox, and a BIG power 2JZ with nitrous too.

I knew JZXs were popular in Russia, but the amount of them, even normal road cars, that run 10sec quarters is mental, but I'm gonna show you this one as not only as it runs high 9s thanks to the obligatory big turbo JZ lump, but also looks cool as fuck...

In the UK we're used to JZXs being drift cars, and are usually 550bhp tops, but in Russia they laugh at a mere 550bhp. The JZX100 below (RWD and 2JZ powered) runs 8.6sec quarters! That will be WELL over 1000bhp then...

Who originally said this shit anyhow? I've seen it attributed to Carrol Shelby, Enzo Ferrari, and Carrol Smith, but did any of them really say it? And if they did, it must have been taken massively out of contact, as frankly, it's a load of rubbish.
Fuck it, as there seems to be no proof who said it, I'm starting a new rumour of who made it up, maybe that'd stop people quoting this shit...

You know though, I'm sure it's a mis-quote, and I think I know where it comes from...

Imagine you had a car with BIG bhp, but a tiny peaky powerband, and a gearbox without close ratios. So every time you changed up a gear, you dropped out the powerband, killing your acceleration. So despite the big peak power number, a lesser tuned car, which was less peaky so didn't drop out the powerband, and no doubt had more low/mid torque, would actually be faster; especially on tighter tracks.
In the old days, where this quote seems to originate from, this would be even more of an issue, especially with heavy "muscle" cars running 4, 3, or even 2 speed gearboxes, which means powerful but peaky cars would easily drop out the powerband and be shit slow compared to torquey but low power cars.
But these days, where you tend to have to either totally fuck up the spec to make it mega peaky, and even peaky engines have closely spaced 5/6/7/8 speed gearboxes, the likelyhood of even a road car being driven properly falling out the powerband is slim, and literally no chance on a well built race car.
That's my theory anyhow- This quote is out-dated and taken out of context.

Anyhow, this quote, almost always used by butthurt turbo diesel owners, low power V6 and V8 owners, and anyone arguing with a Honda owners, just makes people who are trying to be clever just sound clueless, like they've never had a proper race or even driven a performance car in their lives. I mean seriously? One tear up with a lower torque but higher power car would tell them their argument is pretty retarded.

When most people talk about torque, what they really mean is low/midrange grunt, and while it's great (I LOVE torque, it makes cars much more fun to drive, in fact it's why I love big boost turbo engines), and it's certainly something any performance engine, road or race, should aim for the maximum of, providing they've got the traction to make use of it, it's not what wins races, power is.

BHP is just Torque and Revs combined. It's a tricky one to explain in words, it's far easier to experience in reality by driving various cars, but torque is the "Strength" of your engine at a set rpm, but the faster your engine is spinning the bigger effect torque has on performance, so torque+rpm = POWER, which is key to how fast your engine can accelerate (providing it can stay in the powerband though the gears, that is!).

First up on the explanation list, a BMW F1 engine dyno graph (allegedly) from the a 2007 2.4ltr F1 engine...

So, what do we have here? Well, it's about 740bhp, and a pretty tiny 230lb/ft of torque.
So 6lb/ft less than a Golf TDI. And with about 150lb/ft at 6500rpm, it's got about the same torque at that RPM as an EP Civic Type-R, which frankly, isn't a whole lot- People make fun of Type-Rs for being torqueless, but F1 engines are no better.
Next up, a standard BMW 335D, 3ltr twin turbo diesel engine...

The above dyno is at the wheels, so I'm going to add about 30bhp/30lbft to these numbers, which about tallies up with the official 282bhp and 428lb/ft figures.
Either way, say peak torque is 428lb/ft, that's 200lb/ft more than a Formula Fucking One engine. And a remapped one is something upwards of 500lb/ft if I remember right, over DOUBLE what one of the modern V8 era F1 engines were.

Does that mean Formula 1 teams are stupid and they should've just used a 335D engine with a £150 plug in remap and be shitloads faster? Fuck no, as only retards think that.

Fuck, even comparing like for like cars, 335i vs 335d, and the 335i is plenty faster, despite "Only" having 20bhp more than the diesel, and about 130lb/ft LESS. Basically, it's not true.

The above picture is about the predictable thing every "Torque wins races" person says next... "But, but, but, WRC cars only have 300bhp but like 700lbt/ft, and they're mega fast, they win races" YES, but they've not got '300bhp' by choice- That's all they can manage because the rules dictated an inlet restrictor to prevent power going higher.
With no option of more power, no issues with traction due to 4wd and sticky tyres, AND a style of motorsport that involves a lot of very slow corners where instant momentary punch of acceleration is a big advantage, you'd be out of your mind not to go for maximum torque to go with the limited bhp you're stuck with.
But for next year the rules in WRC are changing once again, inlet restrictors bigger than ever, allowing more than 400bhp if I remember right. So will they still go for maximum possible power, if it's "Torque that wins races"? Fuck yes they will, as it's power that's the no1 performance enhancer.

Another argument by these people are "So, if torque isn't important, why do drag cars run big V8s?". Err, mostly as they're the easiest to get POWER from you clowns. The above car is Larry Larson's S10 10ltr twin turbo V8 pickup truck. Yeah it's got fucking shitloads of torque, but the reason it runs 5sec quarters at over 240mph is because the bloody thing has upwards of 3000bhp!
Torque is a BAD thing for him, and because of this he deliberately launches at just 8psi of boost, as at full boost it'd make so much torque it'd just smoke the tyres. In fact it's only ramped up to full boost (50psi!) by most the way down the track and he's already doing over 180mph! "Low RPM V8 Grunt" is literally no issue on fast drag cars either- Larry's car never sees under 8000rpm for the whole run after 1st gear!
So once again, power wins races, and in fact, torque can slow you down if you've got more than your tyres can handle...

Why do so many really, really, fast drag cars run centrifugal superchargers, despite turbos giving far more power, and positive displacement superchargers give far more torque? Because turbos and positive displacement superchargers give TOO MUCH torque for the grip, meaning too much wheelspin for any given power level, making them slower overall. Centrifugal chargers increase boost linearly with rpm, giving LOTS of power, almost as much as turbos, but adding only a little extra torque, especially at low and midrange rpm, so they are FAST due to the big power, but still don't wheelspin due to the lower torque.

It's the same reason a lot of the fastest FWD track cars run centrifugal chargers too- FWD is grip limited, and they need big power to "win races", but don't want too much torque or it overpowers the tyres, and thanks to the power delivery of the centrifugal charger they can use more throttle more of the time without it being wasted in wheelspin.

It's the same reason many production turbo cars, and most the fastest turbo race cars, run lower boost in lower gears and lower rpm, compared to in higher revs and rpm- To limit torque so they've got more traction, making them far faster overall.

It's also why naturally aspirated 2wd rally cars are often as fast, or faster, than the 4wd turbo rally cars, on grippy dry tarmac surfaces (where 4wd was no advantage), despite having the same power and often well over 400lb/ft LESS torque- Because its POWER that's the number one performance enhancer, not torque. This happened a lot in the late 90s, with the 4wd turbo WRC cars vs the N/A FWD F2 Maxi Kit cars...

Fuck no! Torque is awesome! Generally, I fucking hate cars with no torque! Surely, if you've any experience of driving at all, you know torque is great, but despite all this, it's not the key need for pure performance.
Low/midrange torque makes for a nicer, easier, car to drive, especially in slow/fast/slow/fast/slow driving, saving you constantly rowing the gearbox to stay at high rpm where the power is. It's why things like Type-R Hondas need driving hard and dropping gears constantly to be fast, and a Golf TDI just needs the throttle planting in almost any gear to go fast- But ultimately, the Honda, with more power, despite loads less torque, is the fastest if both are driven on the limit.
I drive like a dick and love drifting, so LOTS of torque to smoke the tyres is great for me too. I actually find a lot of drift car setups bizarre, as they ideally want torque but the engine isn't tuned/specced for it.
And regardless of drifting, I like BIG boost, as boost = torque, and torque = fun to drive, BUT if I wanted to go as fast as possible, while I'd want the MOST torque my tyres could handle- I'd not want more than that, as it'd be pointless.

So overall...
TORQUE = GOOD.
TORQUE IF YOU GOT THE GRIP FOR IT = FAST
BUT FAST? = POWERRRRRRRR

After the huge popularity of the feature I did on the awesome but barely heard of Ferrari twin turbo V6 HERE, I decided to do one about an even more obscure F1 Turbo engine...
​
​Alfa Romeo are famous for making oddball stuff, and this engine is no exception, having a turbo setup I've honestly never seen on any other engine before or since, but this engine was never raced, info and pics are scarcer than any other...

Alfa already had a F1 Turbo engine in the 80s, a twin turbo 1.5ltr V8 that's very fucking cool and I'll probably do a feature on in the future, but allegedly due to the plans to change the capacity rules down to 1.2ltr in 1988, they designed a new four cylinder engine, which was to be used by Legier (in current spec 1.5ltr form) for the 1987 season.

As the pics show, while the engine was a normal inline 4, twin cam, 16 valve engine, using two fuel injectors per cylinder, it was also twin turbo, but in a VERY unique way, which to be fair, I'm still struggling to understand the reasoning for.

Twin scroll single turbo setups on 4cyl are very common and VERY effective (25psi+ typically by 3500rpm on a 2ltr with a 600bhp capable turbo), which split the exhaust gas flow from cyls 1+4 in to one scroll of the turbine housing, and 2+3 in to the other.
Using twin turbos in a similar way, using cyls 1+4 to one turbo, 2+3 to the other, works in the same way, though rarer as there's little/no real advantage over a single.
Look at the piping on this one though, it's not twin scroll or twin turbo as we know it, in fact I'm not 100% what it is to be honest.

There's 8 exhaust ports, one per valve, which is rare, but not unheard of even on some production engines (Pug 405 Mi16 for example), but if you look, the ones from cyl 1+4 don't go to one turbo, and the ones from cyl 2+3 don't go to the other, in fact it looks like the front exhaust port runner from each cylinder goes to the front turbo, and the rear exhaust port runner from each cylinder goes to the rear turbo!
Exactly what good that would do I can't figure out, in my mind it would do no good at all, as it'd be no different to a single scroll single turbo setup.

The engine produced 850bhp at 4bar boost in early testing/development, but was massively slated by the test driver for terrible drivability and reliability, and was canned before ever being raced, so maybe this bizarre turbo setup really was as cool looking but pointless as it seems. Here's a few more pics, about the only ones out there, showing how the intercooler and external wastegate pipework was laid out...

There's rumours initial testing used a single turbo and 4 exhaust ports, then twin turbo but still 4 exhaust ports rather than the final version which had eight, but I've never seen proof of this via pics or anything else; it's really about the least documented engine there is, which is a shame, as I'd love to know more...

To finish this off, here's a couple of pics of the test car running the engine, showing the fucking enormous Behr intercoolers these badass F1 Turbo engines of the 80s ran...

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...

Stav

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...

Ok, here goes. First, let me introduce you to Mr Compressor Map, with some basic annotations via the amazing medium of MS Paint...

As you may or may not know, the horisontal axis of the map is airflow in lb/min, the vertical is pressure in bar (1.00 being atmo, anything above being 'boost'), and anything within those lines drawn on the map is the 'safe' area that turbo is happy enough to run in constantly, in this case, up to about 2.4bar of boost and 49lb/min.

The three dots I've added show three different situations.

ON BOOST- 1.7bar, 42lb/min airflow, well within the map, it's loving life.

SUDDEN CLOSED THROTTLE WITH A BOV- BOV opens, so pre-throttle pressure rapidly drops to zero, while an open BOV means airflow is less but exists, and therefore the compressor drops to a very low speed point on the map. It's still safe and happy.
​
SUDDEN CLOSED THROTTLE WITH NO BOV- Throttle closes, so airflow drops to practically zero, while pre-throttle pressure momentarily spikes, putting the compressor in to somewhere on the top left of the comp map (ie lots of boost pressure, but fuck all airflow), well in the surge zone, which, if there were speed lines shown, would be a shitload of rpm too.

Ok, this is where the THEORY vs REALITY thing comes in to tuned cars yet again.

There is NO DOUBT the sole use of a vent to atmo BOV is to help prevent turbo damage via compressor surge and overspeed, as that deffo, deffo, does no good for performance.

In THEORY then, running one is a very wise move indeed.

But in REALITY, how many people genuinely have issues when running without one, even with big boost and hard use over long periods? Well, not fucking many at all.

The issue people seem to forget is severe surge and overspeed happens for a TINY amount of time on a turbocharged engine when you close the throttle.
It's not like a belt driven supercharger, or a gas turbine, or when surge happens ON THROTTLE. That is fucking continuous until the power is shut down, as the compressor is being FORCED to operate at that condition- THAT can be bloody disastrous in some applications as there's huge forces turning it regardless, hammering the shit out of the compressor.
But when you close the throttle on a turbo engine you are stopping power to the engine, and in turn stopping practically all power to the turbine wheel, which is what turns your compressor, so once the slight momentum from being off throttle is gone, there's no danger.

In all honesty, in my 18 odd years of messing about with turbo cars, working around and with turbo cars, testing and timing turbo cars, and reading every worthwhile turbo-related thing on the internet, I've personally seen TWO instances I think 'probably' were no-BOV related turbo fails (both on the exact same type of (uncommon) turbo with a known weak shaft, both at over 30psi), and heard of a few others on huge turbo mega boost V8 drag cars where the turbo failed at the end of the run just after they got off the throttle.

All the other times I've seen turbo fails, it's been other issues entirely. And that's thing, though a turbo CAN fail due to this, it's usually broken due to some other reason long beforehand!

On my own personal cars, even running 1.5-2bar boost for long periods on loads of cars over the years with no BOV I've had no issues, and know countless others doing the same. Christ, I've not ran one on anything since the year 2000 now I think back. And by then I'd experienced plenty of split/leaking BOVs, and have since on other cars too.

Ignoring my own experiences, and the fact I love the sound of turbo chatter, let's look at things logically...

Instances of people talking about their turbos failing that's honestly likely attributed to no BOV- VERY FEW.

Instances of people with fuck all 1st hand experience of the subject telling you to run one for whatever reason- FUCKING LOADS.

% of people with turbo fails that do run BOVs and dont run BOVs- About the same, as frankly, turbos tend to fail for various other reasons before the fraction of a second of surge and overspeed would kill it.

% of turbocharged works race cars since the early '90s that run BOVs- Very very few. Even in the 80s and early 90s they were rarely seen on a lot of applications. If they could improve the odds of ending the race, even slightly, and not cause other, much more serious, downsides, would they run them? Of course they would. Having said this, they use some good, strong, expensive, turbos on works race engines...

Neither, there's no simple answer- I'm saying read what I've told you and make your own mind up- I'm not taking responsibility for your decisions.

For me, personally, no, I never run one. Ran tons of cars at mega boost, hard used, all kinds of turbos, for years, never and issue. Loads of mates do the same, even on fancy big bucks ball bearing turbos, no issue. 
My old R32 Skyline I built, what, 4+ years ago? 1.5bar+ boost, 470bhp, from a journal bearing Holset-based turbo I bought from Compressor Racing (their RS341 model- Like a slightly improved HY35). No dump valve fitted of course, used hard as fuck by me, and hard as fuck by the owners since, track use, drift use, top speed, all sorts- Turbo is still going strong.

Does this make it gospel though? No.

Would I still not run one if I happened to own a turbo with a KNOWN issue of shaft snapping or wheels exploding with not running one? No, I'm not fucking stupid.

Would I risk not running one on some crazy expensive turbo I couldn't afford to fix? No, as I'd not buy one in the first place. Should you? Well, read the above, do your own research, and make your own choice...

Remember though- Only listen to people with NO motive either way (ie they don't sell turbos or BOVs), only listen to people with proven experience on the matter, and remember, someone saying "Well I've got a BOV and my turbo hasn't ever broken" is like me saying I've got a magic stone that protects me from Gorillas and that's why I was never attacked by Harambe...

Stav

Rear mount turbos are pretty new to the tuning scene as 'tuning' goes, having only becoming well known in the last decade or so, and even now are relatively unheard of in the UK. Therefore almost every time they're spotted they're always treated with amazement, both in good and bad ways...
​
The problem is, people's opinions of them tend to be polar opposites of each other.

MOST people, due to it being totally against everything they know, instantly say it will be laggy as fuck, won't spool, will be shit, and so on and so forth.
They're wrong if it's done right.

On the other hand, you got people, again have no actual experience of it, but love the idea and have seen a few on the internet, who tell you rear mounts are amazing, the best way to turbo, as good as a front mount, and so on.
They're also wrong.

Basically, rear mounts are neither shit or amazing, though they're perfectly possible to be shit if done incorrectly, just like a front mount turbo can be. What they are is simply another option if a front mount isn't viable for some reason, and done right can work fantastically well, often far better than most front mount setups, which are often sub-optimal, even when a 'pro' has designed them...

If ALL ELSE WAS EQUAL, a front mounted turbocharger IS BETTER, no iff's or but's, it is. But things never are equal with turbocharging, and there's a multitude of reasons a rear mount setup is useful in some applications, and if done right, they can perform as good or better than a typical front mount setup.

The E55 AMG rear mount I helped build for Compressor Racing was a perfect example of the above. Just like a whole lot of cars, there's next to no room in the bay for a turbo or two, so even IF it's possible, you'll likely be spending a few grand on custom manifolds, even before anything else. And then you've still got to find room for the intercooler, and then deal with the heat management issues for all of that too.
The only other option for the E55 is a supercharger conversion, that costs at least £7000 plus fitting, and makes about 500bhp at 9psi boost, about the limit of the stock (albeit modified) ECU, as we found ourselves.
The E55 rear mount turbo we built was on full boost by 3000rpm (despite a turbo capable of 1000bhp!), and the only time we put it on the dyno it made 465lb/ft at just 4.5psi and due to boost control issues we were only at 2psi by peak power but it still made 440bhp- About 90bhp more than standard.
In the end we sorted out the fuel and boost control issues and got it safely at 9psi. It was never dyno'd at this level, but it WAS timed with Racelogic timing equipment, the proper pro stuff magazines and companies use, not some crappy app or a stopwatch, and the results, despite horrendous wheelspin, were pretty impressive to say the least...
60-100mph time was 4.4seconds at best (backed up by a number of 4.5s runs).
To put that in to perspective, the later, best part of 500bhp, factory supercharged version of the E55 AMG does 60-100mph in 5.5seconds, over a second slower, and even a supercar like the Ferrari F360 is 4.6sec!
And it even made a pretty fun drift car, despite being a huge, heavy, rusty old boat, as these pics show...

And how much did the full rear mount conversion on the E55 cost to do, inc all the non-turbo related bits, such as the uprated fueling parts and so on? Under £2500. 
You'd not even get a pair of custom manifolds made for a front mounted turbo setup on the same car made for that, and even if you did, will be spool a 1000bhp capable turbo much sooner than 3000rpm? Would you even want it to? Probably not for both accounts, and it'd be highly unlikely to make much more power at the same boost either.

While it's MOSTLY pure lack of room that makes a rear mount particularly tempting, it's also been done, even with very high end race cars, for weight distribution reasons, and the simple fact that, done right, it isn't a big disadvantage...

So does this mean we should ALL have rear mount turbo cars? FUCK NO! If you've the room to easily do a front mount turbo setup that's not a complete fucking bodge or cost an absolute fortune, you may as well just do that. As said already, if all things are equal, it will spool faster and make more power than a rear mount. It might not spool loads faster and make loads more power, but still, really no point for a rear mount unless it makes things a lot easier for whatever reason.

BUT as it often does make life easier, I'm sure most are you are thinking "Ok, but say if I do want to go rear mount, how the FUCK do I do it so it's not the laggy mess the naysayers say? How DO I make it as close to as good as a front mount as possible?"
Well, I better tell you what I know and have experienced...

MANIFOLDS- Use standard cast log ones, or short runner tubular ones at very most. For fastest spool you want to minimise exhaust length and maximise heat retention, and regardless of turbo position, long runner exhaust manifolds have very little effect on peak power on turbo cars anyhow.

PRE-TURBO EXHAUST DIAMETER- This is one so many people get massively wrong, and hugely over-do. Treat all your pre-turbo exhaust like you would your manifold on a front mount system, so with a T3 flange and even 600bhp+ a single 2.5in pipe is more than enough, and a single 2in or 2.25in is plenty for lesser power cars. Even with big V8s running over 140mph in the quarter mile, a single 2.5in pipe leading to a T4 flange turbo is well proven. Overly big exhaust diameter will drastically slow spool, and is the biggest killer of performance on rear mount setups.

PRE-TURBO EXHAUST LENGTH- To minimise heat loss, shorter is better, so if you can actually have a mid-mount turbo rather than rear, even better. Just behind the front seats? Instead of passenger seat? It's all been done...

PRE-TURBO CATS- I've not experienced this one first hand, but while basic theory says they'd be bad for power and spool, they're fitted to a great number of very powerful but emissions legal rear mount cars. It's possible the reason they're not the spool killer you might imagine is because post-cat exhaust temp is incredibly high (it's part of their job), which will help maximise exhaust energy and heat at the turbine. But I've never tested this so that's speculation...

BOOST PIPE LENGTH- As discussed in THIS feature, boost pipe length isn't actually a big deal at all. Don't make it longer than it needs to be, but of all the things to fuck up spool on a rear mount, this is a minor one.
One thing you might want to take in to account, though on smaller engine applications (or just using bigger boost pipes) it's likely not an issue, is the instant off-boost punch at very low rpm or just as you open the throttle. On small capacity cars there's not a lot unless there's boost anyhow, but on the AMG it had a huge V8, and once it was rear mount turbo, sucking through inlet pipes 10 times as long but about half the diameter of standard, it lost a little of this punch. You'd not notice unless you drove it back to back, and even then I only really noticed as I wanted maximum punch for drifting, but it was there.
I had a solution though, I fitted this flapper valve taken from a Volvo boat engine, allowing the engine an alternative way to breath in N/A mode...

INTERCOOLING- Yes, compressor outlet temp is lower in a rear mount. Yes, the long boost piping allows for more heat loss. But regardless, the inlet temps aren't that much lower, so if you've got room at all, you'd be mad not to fit an intercooler or chargecooler.

POST TURBO EXHAUST- As explained in THIS feature, bigger is better, and with rear mounts needing all the help they can get, as big, and as short, a post turbine exhaust, the better. Even with a 2.5in pre-turbo exhaust, noticeably faster spool has been achieved by going from a 3in to 4in post-turbo exhaust. As a rule of thumb, your exhaust diameter should be AT LEAST 1.5 times your turbine wheel exducer diameter for best spool...

HEAT RETENTION- This is a big part of spool for any turbo, and a HUGE issue on rear mounts. Basically, the hotter the exhaust gas is by the time it gets to the turbo, the better your spool is. So heat wrap ALL of the exhaust, front to rear, double layered if you can, and of course, put a turbine blanket around the turbo too. The difference between heat wrapped and not is very noticeable.

TURBO POSITION- Under the car is most common, and nothing wrong with that at all, as long as ground clearance isn't an issue. On the Merc we went boot mounted, which personally I prefer for packaging reasons. When we did so we got no fucking end of people saying how can it breath in there, we need to cut holes to let air in, etc etc etc.
Nah, not really.
Boots are FAR from air tight, thousands of small holes and gaps which overall make up to far bigger than a typical 3-4in inlet of an airbox, and the boot itself works as a giant airbox.
No matter how many times we said this, people still said it, so in the end we drilled some holes in the boot to see if it made any difference at all.
Nope, not a fucking sausage, exactly as expected.

​WASTEGATE POSITION- The "Normal" rear mount position is right by the turbine inlet, but IMO they've decided that with zero testing and just their guess. IMO it's wrong. For me, the closer to the engine the better. The WW2 planes and the top drag cars have the wastegates just after the manifold collector. And I'd be more inclined to listen to war winning aircraft and cars that run 190mph in the quarter than some random other person who's probably not tested either way.

OIL FEED AND RETURN- While you certainly can have a stand-alone oil system for a rear mount turbo, it seemed like added complication for little benefit to me, so on the ones I've had dealings with, we've always just fed the engine oil the traditional way- An oil feed pipe direct from the engine.
Oil return is a bit different though. You NEED an electric scavenge pump so suck and pump the oil back to the engine, it won't go on it's own, you'll just end up with a smokey fucked mess. One bonus is, you don't have to return to the sump like on a conventional gravity oil return, anywhere will do- On the E55 we returned to one of the cam covers! 

TURBO SPEC- This is the biggie. Compressor side, well, it should be the same as you'd choose front mounted for the power you want. Turbine, well, smaller improves spool, but also increases backpressure which kills power, and personally I'd not be going much smaller than I would front mounted, maybe not any, and just concentrate on optimising the setup as per above. Just be conservative on turbine size, sensible, as you can't get away with overkill as easy as front, but the exhaust gas still needs to come out, and having a tiny turbine to try and get good spool is why so many rear mounts make shit power for their boost level.
Of course, there's OTHER options to allow a massive turbo without the risk of killing spool.
On the E55 AMG we did for Compressor Racing we used a variable geometry turbine turbo, a Holset HX55V VGT unit in fact, a flippin' huge 1000bhp capable beast. VGT turbos, while not the magic solution to all our woes, have the ability to spool like a small turbine, and flow like a large turbine, so are very useful for rear mounts.
The issue is big VGT turbos are rare as hell in the UK in good condition, and the poxy little ones used on diesel cars are useless, so it's not an easy solution.
Another idea is twin rear mount turbos, compound style, one small for spool, one big for power. I'm currently building a rear mount setup like this now.
Finally, and one I've never seen tested, but I'd like to try one day, is the effectiveness of twin scroll. I don't think it will be a magic solution, but for cars with a very easily done twin scroll setup, mostly inline sixes and twin rotors, I'd be inclined to run two small pipes to the turbo, one to each scroll...

AND THAT'S THE BASICS FOR YOU...
There's a whole lot of bullshit, incorrect 'facts', guesses, and downright lies about rear mounts, but hopefully what I've told you will set a few things straight, and to be honest is plenty enough, if you choose to follow my advice, for a pretty well performing rear mount setup.
BUT DON'T FORGET! Don't do it if there's no good reason to...

OH! Forgot to mention something that's actually a BIG plus point, as childish as it may be... IT SOUNDS FUCKING MENTAL. All you can hear is turbo spooling up and down, super loud chatter and spool and everything else. Sounds like your car has a jet engine rather than a normal engine, which is amusing. Click HERE to see a short vid of the AMG, inside and out, to see what I mean...

​And of course, it looks cool too...

This isn't tech for once, it's more of a rant, or a public information service. Partly as this came up in my 'Facebook Memories' earlier, and partly as it happened to me yet again this afternoon.

In case you don't know what the 'loser flyby' is, it's when two cars end up having an impromptu race on a quiet road, and once it's over, the loser, in a fit of rage/butthurt, does anything he can to get in front, even though the race is long over, and usually while driving in some retarded dangerous way...

Most of us have probably seen this plenty of times, and the car doing it can be anything. More often than not it's not a modified car though, it's just some dick with either something 'quite' quick who's upset and can't fathom/bear another car to be faster than him, or some nobhead with a new but slow lease/finance car who thinks just because it's new and he is spending half his monthly wage just to pretend he owns it, it cannot lose.

Undertaking once the race is long over doesn't make up for you losing, it doesn't save face, it doesn't make you the winner, it just makes you look like a fucking dickhead and tends to show you're really wound up about something that was just a bit of fun to the other driver.

BUT, to be honest, I love people doing the loser flyby, mostly as it's really funny seeing someone getting wound up about nothing, fighting back the tears, being so angry that they think doing such a retarded thing is going to save face.

The one this afternoon was some random de-badged, newish, modified Audi A4 that tried to race me in my E46. Whatever it was it wasn't very fast, but then once in traffic it did the loser flyby undertake down a bus lane about 2 miles after the little tear up has finished. Yeah mate, impressive.

The one in today's Facebook Memories was from 4 years ago, and I don't remember it, but I think I was in my YB Cosworth powered MX5 at the time. It says...
"BMW tries to race, gets destroyed, does the loser flyby on a roundabout to make himself feel better, but misses his exit by doing so. He then has to right round the roundabout and back behind me. Then has another go, gets destroyed again, then sits right back for a few miles until his turnoff, and then does the loser flyby once again." 
I mean, what the fuck?

It's most fun when the attempted loser flyby massively backfires though...
I remember an E46 M3 owner so desperate to do the loser flyby on the motorway when I was in my old Skyline he had to literally cut me up at stupid speeds leave at his junction, and then proceeded to almost wipe out in to the Arcmo, fishtailing all over the shop on the sliproad.
Also seen a car plow in to a ton of road cones in some road works in an attempt to do a loser flyby, and no doubt you lot have seen plenty of similar stupid shit.

There's nothing wrong with a little tear up vs another car if it's safe to do so, it's fun, and win or lose I'd be like 'thumbs up' or whatever. But people being so butthurt about losing that they do a loser flyby just makes them look like massive, massive, dickheads.

I'd hope anyone reading this isn't one of 'those' people, but if you are, fucking don't! Feel free to send anyone who does to this a link to this article mind...

TECH ARTICLE TOMORROW! Promise...

I've known Thomas Zurawski for years, right from when he operated from a tiny little workshop in central Gloucester, in fact we now live 5min down the road from each other, but he has nooo fucking idea I'm writing this (TBF I only decided it'd be an interesting feature earlier today), so this will be a surprise to him to say the least.
One thing's for sure, I'm glad I know him, in fact I think all of his customers are, as he's the type of tuner I think we all expect/hope tuners to be in our heads, but in fact are rare, and that's someone who can basically create pretty much anything you can dream up.
No matter how unusual or one-off, he finds a way to do it.

I've worked with and for tuners constantly for the last 15 years, and I've seen it all. From amazing unsung geniuses, to appallingly bad and shouldn't be in business. From basic hot hatches to Formula 1 and WRC cars. From backyard tuners to enormous warehouse sized places.
Ignoring the bad and even the average tuners, and just talking about the great ones (I'll try and talk about some of them in future features), they generally do whatever they specialise in brilliantly, but most, totally understandably, stick to what they know, stay well within their comfort zone, and just do what they do best. If any requests come in for something very different, it's generally either discouraged/refused, or will be hugely expensive as any work they don't specialise in will be farmed out elsewhere.

When it comes to custom fabrication it's a similar situation too, as I know a lot of absolutely incredible fabricators, some of which would make a good feature on here too actually, but again, wisely enough, they stick to what they know best.

Because of the above, I've found over the years, and no doubt most of you have too, getting custom work made, unless you're very rich or can do it yourself, is very, very tricky.

But this is where Zurawski Motorsport is different, as Thomas is genuinely the only person I've ever met who I can go to with strange/crazy/one-off tuning ideas, and not only does he always say "Sure, we can do that", but he's not bullshitting either. He not only has the fabrication skills, but he genuinely understands tuning too, so what you have in mind, what you hope for, is what the end result actually is.

I first used him when he was fairly unknown, 6-7 years ago, to weld a few things for me. It was simple stuff, but I heard he was a shit hot welder, and was local, so it was ideal. From these basic jobs and talking to him, it became clear he knew what he was doing with tuning as well as fabricating, and as I had an idea in mind, and couldn't previously find anyone who'd do it, I went to him with a couple of bits of metal and what seemed to me like a good idea, and the rest is history.
What I wanted, but didn't exist, was a super short runner twin scroll turbo manifold for a 13B rotary engine. All manifolds available then were longer runner than I wanted, single scroll, or both, and was told what I wanted didn't exist as it wasn't possible.
I explained what I wanted and why, and within a few days he calls me and says it's done...

As time's gone on, Zurawski Motorsport has moved to a much bigger premesis in Ledbury, and the main things he now does are almost 'production' parts rather than 1-offs, albeit ones that didn't exist (or indeed were called impossible) until he designed them, such as the Toyota 1UZ V8 engine and manual gearbox conversion parts for 3-Series BMWs, big power twin scroll turbo setups for RHD inline 6 BMWs, and 1UZ V8 big single turbo conversions, all of which he sells to customers all over the world...

But why Thomas, and Zurawski Motorsport in general, has ended up with the large following and the respect they have, is because everything the company has done originally comes from an individual customers crazy idea/dream, and while others say they can't do it or expect horrendous money to do so, it's always the same "Sure, no problem" from them, and the result is mad shit like this...

Mid-engine SR20 Time Attack Silvia? 
​"Sure, no problem"

No, forget the SR20, fit a 1UZ Toyota V8 and a flippin' massive turbo in the same place.
​"Sure, no problem"

Twin scroll tubular manifold on a tractor with a massive Holset turbo?
​"Sure, no problem"

What about a BMW V8, in an E30, with twin turbos, massive intercooler, and a WRC style direct port anti-lag system?
"Sure, no problem"

Why not build a completely custom bike, and I mean REALLY fucking custom, even make the bloody frame and wheels yourself?
"Sure, no problem"

How about build a twin turbo setup with ITBs and insane custom plenum for some crazy off-road lightweight race truck?
​"Sure, no problem"

Make a WRC/Rallycross style twin plenum equal flow intake for an RB20 and help it produce 470bhp (on stock head/cams) that has full boost by just 4000rpm (despite a 600bhp rated single scroll turbo!) that's still going strong after many years of hard use?
"Sure, no problem"

Massive single turbo setup for an E34 BMW 540i?
"Sure, no problem"

E36 BMW with a 1UZ V8 engine, massive turbo, and WRC anti-lag setup?
​"Sure, no problem"

But these things don't just look mental, the ARE mental. A big thing I like about Zurawski Motorsport, and why I've used them for so many of my stupid projects and ideas, is Thomas REALLY gets tuning, and works things out properly via a mix of sound tuning principles and his own experience. Steve Will's awesome E36 M3 turbo is a good example of this. It already was a 700bhp turbo monster with a fully forged engine, but he went to Zurawski Motorsport not looking for more power, but similar power but with a much improved powerband.
So off came the log manifold 99% of RHD turbo BMWs use, off came the stock inlet plenum, and what was fitted instead was the Zurawski twin scroll manifold and twin plenum equal flow inlet manifold, a setup Zurawski Motorsport now has available to any customer who requires it.
And, well, the difference in how the car performs, despite the same size turbo and not a single change to the engine internals, is nothing but incredible, as the dyno comparison below shows...

A big big reason why his stuff works is, unlike many (though they'd never admit it), he really does calculate and measure everything rather than make a best guess, and it's actually quite odd/bizarre when you see him do it, especially for someone like me that sucks at maths, as he does it mostly with a pencil and paper, like so...

It's also worth mentioning his shit is STRONG too! Unlike so many exhaust manifolds which crack all the time, his stuff is made from thick, and top quality, stainless steel, and welded not to look pretty in internet pics (though it does), but to be fucking bulletproof, even with hard anti-lag use and so on.
​To the extent customers have had quite big crashes in their cars that bent chassis rails and so on, but did the manifold crack? Nope.

So yeah, it's not a big flashy company, but what Zurawski Motorsport does it pretty unlike anyone else I've found in all my years of pissing about with cars in the UK, and while I'm not easily impressed (there's only a handful of other tuners I can think of off the top of my head I'd like to write about), anyone who can so consistently produce such mental stuff as him, without the kind of WRC-style budgets and huge staff levels this kind of craziness normally comes from, gets my vote...

To see more, check out the Zurawski Motorsport Facebook page HERE, and there's a website HERE too.

This might be obvious to most of you, but it's a very common mistake a lot of people make, and actually leads on to some interesting points others might not realise either, so this is worth a little feature...

While turbine housing size is hugely important, and plays a key part in how a turbo performs, on almost all turbochargers, compressor housing A/R isn't a performance issue at all, so don't worry about it, and stop quoting it, please.

The reason I'm writing this is because it's very common for people who aren't exactly turbo experts, especially when someone asks them what A/R the turbine housing is, or when they're listing one for sale, to quote the compressor housing A/R instead. The reason they do so is pretty understandable, as it's usually pretty noticeable on the front of the compressor housing, so it's much easier to spot than on the turbine, especially when still fitted to an engine.

While it's easy to spot, in 99% of applications it doesn't mean anything, and will be near as damnit optimal from the factory, and with no other options available anyhow.
For this reason, it's only really Garrett and BorgWarner who ever even print it on the housings- It's never mentioned on Holsets etc as they're all damn big and therefore pretty much perfect, and because of this there's no other options regardless.

Having said the above, and maybe it's a coincidence, but the only manufacturers where occasionally a larger compressor housing can benefit some turbos, especially when they're pushed hard, is Garrett and BorgWarner. 
On Garretts the ones that benefit are things like the GT28RS, GT2871R, and even GT30R, that have optional smaller 'compact' compressor housings available, which make them direct replacement turbos on things like SR20DETs etc. These smaller compressor housings aren't the optimal ones for flow, but they serve a purpose to make larger than normal turbos fit in the stock space, so it's a compromise you may have to make in some applications.
On BorgWarners, some S200s, S300s, and S400s it's an option sometimes too. Thanks to the HUGE amount of OEM engines they're fitted to, Borgs often have a variety of compressor housing sizes fitted to what's essentially the same size turbo, and the bigger ones generally perform better than the smaller ones.
With Borgs it's become such a big thing that these bigger, higher flowing compressor housings have become known as "RACE COVERS", as they're proven to perform significantly better, despite the fact they're mostly the OEM parts from JOHN DEERE turbos; yes, tractors and so on! Of course, "RACE COVER" sounds sexier and sells more parts than "TRACTOR COVER", despite the fact most modern John Deere engines have some of the best turbos in the world fitted to them as standard.

Better compressor housings for Borgs have actually become big enough business that true aftermarket ones exist too, and they're not cheap, but they look cool...