exhaust size

[crazygt]

what do you guys use when puttin in a straight pipe,is there anyone on here with 3inch piping?i have on 2.5 now do u think there would b a difference?i would like to no urgantly so i could do this tmrw if anything

 

[CMR]

2.5 flows fine for anything upto and over 300 bhp.

3.0 all the way through is too big imo

 

[turbojim]

like cmr said bud 2.5 is big enough i have 2.75 and its definately big enough even a little too big

 

[dac69er]

i had a full 2" exhaust and replaced it with a new system that when from 2.5" most of the way to 3" towards the end. i noticed no difference in performance with a hybrid

 

[crazygt]

ok gd gd thanks to no,now i dont have to go and spend nuff money to replace it lol

 

[I_<3_Boost]

Just out of curiosity, when people say, The think its to big would there be a performance loss, if the pipe was to big? Because I always thought turbo cars need little or no back pressure, then I was told difference, this woud therefore change spoolup times?

 

[munday]

Just out of curiosity, when people say, The think its to big would there be a performance loss, if the pipe was to big? Because I always thought turbo cars need little or no back pressure, then I was told difference, this woud therefore change spoolup times?

You won't loose any power with a larger bore exhaust, bigger is always better but it's a law of diminishing returns. Upto 300bhp going from 2.5 to 3" piping will get you a minimum power gain (if anything) and a louder exhaust note.

With a turbo car you want to maximize the pressure difference between before and after the turbo.

 

[CMR]

Its just overkill, its only worth going 3" all the way through if you are some how flowing so much gasses through the turbo that you are restricting power on 2.5" piping. On a starlet I dont think even the big turbos people fit would flow enough to be restricted on 2.5" piping.

I might be wrong on that last point, but in general 2.5" is fine for most people.

 

[dantheman]

2.5" is fine even for high powered motors. 3" is overkill but shouldnt see any negative effect other than changing the exhuast note and loudness.