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.

[s8 d2]

would K03 turbos be up to the job? i mean running 21 psi on my old s4 2.7 v6 twin turbo car was running 340bhp/585nm but k03's were maxxed out

would have thought using k04 rs6 turbos would make more sense no? just didnt think k03's running 6-8psi would do anything on a 4.2v8

just my 2p worth

[71camaro]

Originally Posted by s8 d2

would K03 turbos be up to the job? i mean running 21 psi on my old s4 2.7 v6 twin turbo car was running 340bhp/585nm but k03's were maxxed out

would have thought using k04 rs6 turbos would make more sense no? just didnt think k03's running 6-8psi would do anything on a 4.2v8

just my 2p worth

I won't be running k03s in this configuration, that was just an example of what has been done stateside in terms of turbos on these cars. For more info on that particular setup, search TozoM8 on the Quattroworld board.

Most likely I'll be using a Garrett turbo, either an older style T04e T4 based turbo or one of their newer GT or GTx designs. The trick is going to be to size the hotside correctly and sizing the piping so that it doesn't become a restriction while also maintaining decent velocity and therefore maintaining boost levels.

[71camaro]

Just spoke to the turbo company and Jeffrey Atwood, my tuner, here's the plan. We'll be running 2 inch (stock sized) piping that has been ceramic coated to a Y in the exhaust. From there, we'll be using 2.5 or 2.75 inch pipe into the turbo. The turbo will be a custom GT35 unit with a .64 A/R exhaust housing. We'll be boosting 8 pounds on 93 octane fuel for an estimated 460 whp. Jeffrey will also be writing a flexfuel tune capable of modifying fueling and timing on the fly. This tune will be capable of producing over 500 whp. At this point, our main worry is the rod strength, as such a setup is also going to produce a lot of torque. Because of this, the car will be receiving a 6 speed swap as well. I've gotten the price for that swap down a lot, into the $2300 USD range. I'm expecting to start collecting parts in the upcoming few weeks.

[Nollywood]

Interesting. I'm still considering turbo charging my S8 motor that's going into my B5 A4Q Touring Car, but may well mount the single snail in the bay. I'm removing the secondary firewall, so that may give me more space. Transmission will also be 01E.

My daily driver '01 S8 will remain stock, bar the 01E conversion she'll be getting.

Just a thought: Have you considered running RS6 pistons? That way, you'll have a safer 9,3:1 CR, allowing more boost and aggressive timing advance.

[71camaro]

Originally Posted by Nollywood

Just a thought: Have you considered running RS6 pistons? That way, you'll have a safer 9,3:1 CR, allowing more boost and aggressive timing advance.

It has been a consideration, but sourcing them is quite difficult here in the US, and costly. The setup I'm looking at, with water/methanol injection, should deliver much cooler charge temps than a standard underhood layout, and so I want to experiment some. My goal isn't having the most power, just much more than I do currently.

[Singh]

Water methanol works well. Grizz's B5 RS 4 does 590 BHP without water meth, and 630 BHP with.

[71camaro]

Originally Posted by Singh

Water methanol works well. Grizz's B5 RS 4 does 590 BHP without water meth, and 630 BHP with.

Have it on my Scirocco 16v G60, only form of intercooling, and the engine is 10:1 compression, no issues, works well

[71camaro]

Well, in my research, I've come across quick spool valves. These are used on divided housing turbos and effectively cut the exhaust housing's A/R in half up to a certain boost level. So, a very large A/R turbo, best suited for high RPM power can still spool and build power at lower RPMs as well. These would seem to be an effective route for a remote mount setup, taking a well breathing turbo (say a GT3582r with a .86 A/R housing) and making it spool in a manner similar to a K03. I'll be most likely using one of these in my build in order to manipulate the turbo behavior and power potential. On an E85 tune, I could effectively build 600 whp (if I don't break internals) while still being able to see boost at 2000-2500 RPMs on a 93 tune and build 450-470 WHP. Exciting stuff, and fairly cheap too thus far (compared to other turbo builds I've done), that I'll be doing.

[71camaro]

Turbo choice has changed. A small company here in the States called Comp Turbo (started by some old Garrett engineers) are producing turbos that don't require oiled center sections, they're self-contained lubed. They spool quickly and are more efficient, and though requiring a bit more money up front, end the need for an oil scavenging pump, and avoid the possibility of a pump failure. They are still watercooled, but that's a trade off I'm willing to make.