devin mac

iTrader: (2)

for the mother ******* WIN

Atlanta93LE

iTrader: (5)

Stretch bent 1 7/8"

Saml01

iTrader: (9)

Whats the diameter of the drinking straws they hand out at the movies?

Markp

That's because the turbine exducer is 3", btw 7-11 degree tapers are thought to be optimum and yes there is proof that this is the case but you can get away with more taper than that. The idea is to keep the transition smooth and yes, it does make a difference on the dyno.

Mark

Markp

On the dyno I was not able to tell the difference between a really nice 2.5" system and a 3" dump pipe that exited under the car on the dyno. It didn't make a damn bit more power. This was with a GT2860R with an internal wastegate.

It didn't even spool any better to be honest. With that small of a turbine at 240 RWHP, the 2.5" system was plenty adequate and a lot more quiet than the 3" dump pipe. I subsequently made 300 RWHP on that same 2.5" system with a T3/T4 hybrid, but I am pretty sure that it is now an issue compared to a 3" system. 2.5" systems are fine up to about 250 RWHP. (I will concede that on a well designed 3" system with an external wastegate you can see benefits of a 3" system as low as 200 RWHP. YMMV)

Mark

TURNS101

iTrader: (10)

Well then, I will have my BEGI DP go into a nice fatty 3" back pipe with the external waste gate dumping to the atmosphere.. By 2008 that is..

Stephanie Turner

We've done 250 whp on a stock exhaust before. (2" or 2.25" I think?)
My car has done 243 on a 2 1/2" exhaust.

Now that the 3" dual is on, I think that the power band is much smoother. There is not the sudden sit you back in the seat. But it has not been back to the dyno. The 3" sound is deeper. I wish I had put the 3" on sooner.
Stephanie

jwarriner

The best exhaust for a turbo is no exhaust at all. Period.

Probably the pinnacle of turbocharged piston engine technology was WWII era airplanes. They ran no exhaust, turbine housing straight to atmosphere, along with lots of other fun stuff (nitrous, alky injection, cockpit boost controllers/overboost). No exhaust is unrealistic on a car but I'd never suggest smaller is better. I may suggest that smaller is sufficient but you'll always have gains with a bigger exhaust, no matter how minute they may be. Period.

If you have the ability to go 3" all the way from the start, do it. If not, 2.5" will probably be fine for anything under 300hp.

spike

^

The pinnacle of turbocharged piston engine technology was the F1 turbo era.Where cars were making 1300+hp in qualifying trim on 1.5 liter 4 cylinder engines.

jwarriner

You got me there.

What did they run for exhaust?

spike

^ I'm pretty sure it was open header/flame thrower.

cjernigan

iTrader: (13)

Ahhh skeet skeet skeet
Man i love F1.