2" stainless

[johnny]

Had my car up on a ramp only to find out my stainless is only 2"

Is it worth changing it to 2"1/4 for power gain?

Will there be much differance?

No wonder ive never had overboost.


Matey in the garage says its not worth messing with.


Just thought id ask.

[TomE]

Depends whether you think £300-350 for a 20% power increase is worthwhile. It's one of the cheaper ways of increasing the power, but you may find you have to do some other mods to get rid of boost creep, like replacement ECU chip and/or wastegate porting (see the other exhaust threads for more info). Confusingly, there doesn't seem to be a pattern re which cars suffer from it and which don't.

Larger bore exhausts, particularly the PECO, also give you a much improved exhaust sound.

If you've got a standard car, are happy with the performance and might want to sell it in the next 1-2 years, it might be worth keeping it standard. But if you've already get mods, want a bit more power and don't mind budgeting for possibly some extra work beyond the exhaust then go for it!

[johnny]

I have a ported wastegate, done it a few months ago, and chip in ECU.

300-350,hmmmm, may just leave it as it is, as its already stainless 350 is not worth

1/4"..


Cheers.

[Nige]

I think you will find a real difference if you fit a larger exhaust. Its a shame to take off a sound 2" stainless but if you want to realise the power the chip will provide (and having already ported the wastegate) the exhaust is the one key element that remains, I hope your brakes are up to it .

[Doug]

I think you will find a real difference if you fit a larger exhaust. Its a shame to take off a sound 2" stainless but if you want to realise the power the chip will provide (and having already ported the wastegate) the exhaust is the one key element that remains, I hope your brakes are up to it .

think of exhaust flow in terms of area of the output tube

using area=pi x radius squared



2" exhaust has 1" diameter ---> area of 2" = pi

area of 2.5 inch = 1.5625 pi

therefore a 2.5 inch exhaust has 156% as much area to blow through!


my point is to show you that a small change can make a significant change!


however remember that any pinch in the system reduces the diameter and affects the flow similarly!!

that said you can get a 2.5" thru the front crossmember area without crimping it if done right!!

[rip]

2" exhaust has 1" diameter ---> area of 2" = pi

I think Doug meant radius.

Figures were correct though. Actually, you don't need to use PI at all. All you have to do is find the ratio of the diameter squared.

2½ = 125% of original diameter. 1.25*1.25= 1.5625 of original area so 1.5625 flow available.

2¼ = 112.5% of original diameter. 1.125*1.125= 1.27 of original area.

Remember that, unlike an NA where everything is balanced for each other, on the SE & S2, the turbo forces the charge through so at high flows, the exhaust's resistance to flow can make a significant difference.

[Gazza]

that said you can get a 2.5" thru the front crossmember area without crimping it if done right!!


Correct Doug

[johnny]

I think you will find a real difference if you fit a larger exhaust. Its a shame to take off a sound 2" stainless but if you want to realise the power the chip will provide (and having already ported the wastegate) the exhaust is the one key element that remains, I hope your brakes are up to it .

Youve just made me spend the misses money.

I could put my 2" on e-bay.. get her a little bit back.