Remote mount turbocharger

[71camaro]

Hello all, I'm a new S8 owner and love the car, however a bit more power would certainly be nice. Over the past several years, I've built a 650 hp turbo 24v VR6 Golf GTI, a 250 hp supercharged 16v Scirocco, and a 700 hp Chevrolet Camaro on nitrous. The S8, with its high compression ratio and very cramped engine compartment presents a challenge for further power production, particularly on pump gasoline available here in the USA however.

Coming from the American muscle car community originally though, remote mount turbo setups are actually somewhat common. The premise of the setup is this: a turbocharger-or two- is placed further down the exhaust track, perhaps even as far back as where the original muffler would have been, and the turbo is sized in such a way as to add correction for the distance from the engine. The boost is usually not intercooled as the piping length acts in such a manner as to provide surface and low ambient temperatures to cool the air moving to the engine. Also, being so far from the engine, the turbocharger runs cooler and therefore doesn't heat the boosted charge as much as the air leaves the compressor.

Negatives are obviously going to be slightly more lag from the charger(s), and placement under the car, though both can be corrected, and with the automatic transmission equipped in the S8, brake boosting can help solve the issue of lag to some degree. The biggest concern, in my mind, would be our weak transmissions and torque converters, though an aftermarket solution does exist here in the US for the TC concern, and that may add some life to the transmission. The other negative is that, with only 93 octane gasoline, boost is very limited due to detonation issues-even 6 PSI would seem dangerous on a moderately sized charger.

In the USA, there is one gentleman I know about with a traditional looking charger setup using a pair of K03 chargers. He runs 6-8 PSI and claims about 480 hp. He is limited due to tuning and available fuels, as well as the charger he selected. There are a few other cars internationally I've read about that are charged as well, though I know nothing of the setups used.

I'm going to be building a remote mount charger setup. I'll be speaking with a company called Squire Turbo Systems to work on proper charger selection. I'm also going to be looking into variable geometry chargers (they're used in a number of OEM applications, and the Subaru community has been adapting them) though controlling the shift in turbo turbine AR will be difficult to do (some have simply added a solenoid that shifts the unit at a particular RPM, not the most glamorous or efficient solution, but one that works).

Perhaps the most important thing I have on my side is the tuner with which I'll be working. I've worked with Jeff Atwood (US head of United Motorsport) before. He's a genious. He and his UK associates have built ridiculous cars and performed ridiculous swaps. One of the great things Jeff has done is crack a number of Bosch engine management systems. He has gone on to create flexfuel tunes for these. (For those not informed, flexfuel is a system GM has worked heavily on in the US that adapts seamlessly between gasoline and e85 ethanol fuel-along with any mixture of the two-to give correct fueling and timing maps for the two fuels). With an e85 tune, boost can be raised greatly, and power increased greatly as well. Thus, when running gasoline I can run 6PSI and have no problems, and on e85 I can run 16 PSI and do the same.

This is an entirely new style of charging than anything I've before done, though the basics of forced induction still apply. With Jeff tuning, and myself and my good friend Sam doing the fabrication work, the project should work and open up a door before kept closed. While remote mount setups are certainly not ideal, they have benefits and do work surprisingly well. I'll be updating here as we commence work and move forward. Expect slow progress at first, though it will speed up as spring comes around.