EpitrochoidMan

Hey everybody, I first posted this in the 3rd gen area but figured here would be a better place. My goal is to 1)Eliminate the crappy cast iron log, we call a turbo manifold and replace it with something made from tubular steel and 2)To replace the high quality hitachi turbos with garrett BB turbos (a GT25r primary and maybe a GT35R secondary, although fitment would have to be worked out) and 3)Still have a sequential turbo system on the car.

I think this can be done by simply controlling 3 wastegates and a butterfly valve. 2 wastegates to regulate the turbos, 1 wastegate to get the desired amount of pre-spool for the secondary and a butterfly valve to transition to the secondary. I've never tried something like this before and I would like any input anyone has on this.

Please forgive my artwork, I did this on MS paint. It's just an idea.

BTW, please don't turn this thread into a single vs. twin arguement, that's not the point.

EpitrochoidMan

Or maybe this would be better

RETed

I think it's a waste of time.
If you insist on twins, I'd rather go non-sequential parallels.


-Ted

EpitrochoidMan

If you're going non-sequential, you might as well go single. The idea here is to get an extremely broad powerband from the engine and still be able easily match the power of a single. In addition to eliminating the rats nest, and cleaning up the engine bay.

drago86

It looks like the exhaust ports are seperated in the drawing, one going to each turbo,.. how would the rotor that had the secondary turbo run below the transition?

EpitrochoidMan

The drawing is bad, I was thinking each exhaust could come out from the port a little way, then merge into like an X pipe before splitting.

wwilliam54

for a wider powerband,a S/C is a much much better way to go IMHO
no need for the complex routeing BS

EpitrochoidMan

I asked for criticism of my design. Not opinions on what might be better. Which BTW a s/c is not. I would rather have a little more exhaust back pressure, than a bunch of parasitic drag on the engine. I would also like to be able to vary my boost on demand, and also be able to produce more than 8, 10, or 12psi without having to change pullies. Yes, you would have power from the get go, but you wouldn't be boosting 1.5bar, that's for sure.

wwilliam54

well its a trade off
s/c for wider band
single for high-end

a good wipple s/c will do as well as those two turbos considering the complexity of the plumbing, and a adjustible bypass valve will adjust the boost

of course you can always go big single with n2o to spool it

and look at the article in (R&T or C&D, cant remeber) about seq setups in the newer BMW diesels, good info