size of exhaust tubing?

[Martin Broon]

im getting a front exit made up, my car is running 220 bhp with a tongs turbo and a access ecu, what size of tubing should i go for? 2.5 inch or 2. 1/4 inch?

 

[fowcbler]

I wouldn't do anything smaller than 2.5"...you might even consider 3"

 

[Skalabala]

2.5"/63mm is perfect

 

[STARLET N/A]

2.5 will be fine

 

[glanzadude]

I am doin the same thing and my pipes are only 2ins, I dont see why it has to be 2.5 are 3?????

 

[weeJohn]

2 inch is ample for that turbo, on a short front exit you will loose power with to big an exhaust.

 

[glanzadude]

2 inch is ample for that turbo, on a short front exit you will loose power with to big an exhaust.

i was thinking so mate as the standard exhaust is only 2ins too dont no why people think it has to be 2.5 are 3ins

 

[Rev]

I read 2.25" still gives a little back pressure 2.5" will give boost creep so is freer and I guess less back pressure. Some back pressure is present from the turbo blades but you need sufficient to get good torque when the engine is not boosting. If you ignore back pressure then reducing pressure before and after the turbo helps get the most out of the turbo, decat, free cat and bigger exhaust all assist in that regard. With an auto car keeping back pressure is essential as the engine uses lower revs so torque must be maximized, with a manual car you have more choice. That being the theory in practise I have 2.25' auto and the initial torque I notice most is at or just before 0 psi so whatever gets me to 0psi quickest is what I would really prefer.