Twin Turbo Project - The Unofficial BMW M5 Messageboard (m5board.com)

Lonewolf · 4th September 2008, 07:50

Hello e34 members,
I wanted to share this with all the members here. I do appreciate the great wisdom on this board and I am a huge fan of the e34 M5.

Although I do not post often, I thought some of you may enjoy this. This project was born from a blown head gasget. It is in the final stages of pre-fabrication and the motor will be pulled next week and sent to Jim Rowe at MM for a low compression complete rebuild. Car is a 92 3.8 with about 70K mi in really nice shape that I bought about a year ago and put much TLC and $$ into.

the plans are a driveable TT with a powerband resembling the original. plan to drive in cool weather mostly. The chasis was ready before the blown head, has many nice upgrades.

The muscle behind this is my friend and head mechanic Jon Firpach here in Arizona. He is a real talent, a BMW fanatic to the core, and a stickler for detail. I must admit that I was very hesistant initially, not wanting to ruin any part of this car. After seeing (and driving) and realizing how far turbo technology has come, I slowly became convinced I could make something worthwhile and still honor the original. I'll be the first to acknowledge if I in fact turn out to be wrong.

I'll try to keep those interested posted in the next several weeks. the photos are of simlpe pre-fab placement, the manifold is being fabricated as we speak. There will be an air/water IC in place of the old air box position.

vadas1 · 4th September 2008, 09:05

Sounds a very intriguing project. Best of luck!

ralph (vadas1)

nebpor · 4th September 2008, 10:06

Looks like a good job!

What are you using for mapping / ECU?

daytonaM5 · 4th September 2008, 10:51

wonderful. beautiful...

Very nice project.

I believe your power band will be full of torque from 3000 rpm till redline.

Your are using twin Gt28? Gt25?

I pondered about twin turbo`ing S38, but went single GT47-88. Right now i am also working on my S38.

Are your turbo manifolds log type or tubular?

Keep up the good work.

Mert

farrell · 4th September 2008, 11:01

Hi
Thats different.

The location for the Turbochargers.

They seem very close to the bulk oil of the engine & transmission.
(Might be the angle of the pics)
Are you going to shield these parts from exothermic heat soak ?
The vehicle has an aux oil cooler which does its job on the std engine.
Have you got any generic or projected engine bulk oil temps ?

I notice that you are running integrated poppet valve wastegates in exhaust housings.
I have found that heat stressed areas where heat can be trapped or exhaust gas temps get
high for extended periods, I have had these poppet valve waste gates seize part open.
The cure was inconel poppet valves or remote waste gates.
The remote waste gates is best solution imho but space is tight here.
How much MAP will you run at ?

Good luck with the old girl

Cheers

Lonewolf · 4th September 2008, 18:22

Thanks for the replies. As to the mapping, this was the luckiest part. Turns out there is a company making a piggyback system to the edc that uses air speed vs. MAF. we went with this system. I'll get the name for you.

The turbos are GT2871R. the manifold is tubular 3". I'll post pics when the manifold is done, Jon does beautiful work here.

Farrell, you are right, the location is unusual. we wanted the car to appear as "stock" as possible from above, and the group in charge felt there was plenty of room properly shielded to place them close. We had already prepared modified engine mount brackets to make sure we could fit dual intakes but we ended up not needing them. We really wanted this car to have minimal lag and I think going with two smaller turbos and placing them where we did should give us the best shot. We plan on extensively shielding that entire area for sure. We are planning an auxillary oil cooler as well. As for the wg we have no plans for remote but I will pass your point along to Jon, appreciated.

The motor is going to be 8.5cr with all lightweight internals, Weisco pistons etc... We plan on running about 12 to 15 psi.

farrell · 4th September 2008, 18:58

Hi
Good reply

The numbers make sense.
The FI profile is shadowing Nissan RB26 DETT engine except with much greater
engine displacement.

Heat is concerning around exhaust hsg's
Depends on use I guess.
In Europe, on Autobahn or some tracks here...phew !
I think your man knows his sh1t though.

Very interesting.
Good luck