Originally posted by fastcougar:
I have searched EVERYWHERE and I can't find what I'm looking for: I need to know the optimal exhaust pipe size for this application (3.0L Turbo). I'm leaning towards 2.25" for the up-pipe and 2.75 or 3" for the down-pipe. I want to keep it a little small on the hot side to keep the velocity up to keep the turbo spooled for quick response. I would greatly appreciate your advice/links to resources!



I'm going to tell you that 2.5" is small enough for the up pipe, 3" if you have an incorporated wastegate should be fine for the down pipe, or you could do a stepped down-pipe from 2.5 to 2.75 then to 3" where the wastegate pipes back in. Or just dump to atmosphere and keep 2.5" back since about 1/3 of your full throttle exhaust is dumped out the wastegate, you won't need bigger than that.

Mine spools quick even with a .82 exhaust trim
With these pipes I have now, I get full 7psi by 2700-2800 rpm, by 3000 rpm it will be at least 10psi and by 3500 it will hit 14psi. Above that I don't know but any lower and you will always have traction issues on a 3L. Hell it is already bad enough at 7psi even if I smooth into the acceleration.

Former owner of '99 CSVT - Silver #222/2760 356/334 wHP/TQ at 10psi on pump gas! See My Mods '05 Volvo S40 Turbo 5 AWD with 6spd, Passion Red '06 Mazda5 Touring, 5spd,MTX, Black