I hear having the pipe go from 2.5" to 3" abruptly is not the best in the world for exhaust systems, so if I was going to have a section of my exhaust flared from 2.5" to 3", how long does the section have to be to reduce turbulence? 12"? 16"? 24"? TIA

 

are your turbo. if not why go 3" at all. IF so go 3" all the way.

 

i posted this question for a friend who is currently turbo, but with a 2.5" downpipe. he's in the process of getting his 3" exhaust together and this is one of the questions that he had. anyone else with any input?

 

If you flare from 2.5 to 3 after the ac compressor you should be fine. It depends on what kinda power you are looking for. 300-400... no problem. Ide say maybe a little over 400. But if you can go ahead and run full 3" do it.

 

he's doing about 350 to the wheels. he also wants to keep his downpipe, cause with the manifold he's running, he doesn't have clearance for ac and ps if he goes with a 3". so back to the original question...

what is the minimum length the flare has to be to reduce turbulence?

 

I would say 12" but where would the turbulence come from if you had a smooth transistion to 3"? Shouldnt have any problems. The shortest possible length of 2.5" is what im saying.