DK

That's what I thought, thanks

matthewk

actually it has alot to do with turbos. you can inscrese the velocity of the exhaust by pipe size.

RM

Yeah, before the turbo. After turbo its called restriction.

JOEL

With turbos you want no restriction after the turbo period. There is no room for discussion in this area. There are all kinds of things you can do from the heads to the turbo but after the turbos you want the least amount of restriction. Go to race forum if you want to confirm.

Biturbo

Mark did a 13.7 run with just the exhaust at the drag strip.

TurboX2

like some one pointed out, works on NA engines or before the turbo. If you really want to maximise exhaust tuning, make a header that utilizes the principles you mentioned. Once the exhaust gases hit the turbo turbine, none of what you mentioned matters. That is why there is so little hp/torque gain from an aftermarket exhaust. The best exhaust for a turbo is no exhaust. Just like the best intake for a turbo is airhorns.

BrianN

If so, what were the differences in trap speeds? Trap speed is a good gauge for HP production.

Sander

At least in the Eclipse world a free flowing exhaust is considered a good thing. I have a 3" catback on my 2 liter turbo charged 95 GSX. On a normally aspirated engine of similar size 3" would be way to big and cause a drop in low end torque. For turbo chargers things change dramatically. I'm no expert in the matter but the exhaust manifold and downpipe (piece between turbo and cylinders) do need to be properly tuned for a turbo engine. After the turbo just leave disconnected if you can stand the noise :-)

Regards,

Sander (95 GSX, Nogaro S4 on the way)

Bill D

I can see that you are pretty serious about this exhaust...

I am no expert, but I've built a few fast turbo cars here and there. I would guess that most of the effects that you speak of would get muffled or eliminated by the turbo. In my experience turbo's need an exhaust that redirects the exhaust gases to a safe exit with the least restriction...that's the only design principle. That is why HKS makes exhausts with 4 1/2" mandrel bent piping for Skylines and Supras...

About the best set-up for a turbo is an airhorn in...and an airhorn out....Now there is a TON of finite tuning in the intake and exhaust manifolds

mark@velosaudi

thats why the "TUNED" crossover dual design is the best for a steet car!!!my S4 will beat a "comaparably" equipped S4, every time!!!my intake and exhaust designs build boost faster...i have been doing HP improvements on V engines for a long time...i have a "WORLDS" fastest vehicle under my belt...no disrespect here, but come on we are talking a street vehicle...