Trying to fill time in work, for me and apprentices.Thought making a new exhaust would kill some time, at the mo I have one with a cat, 3" going in, 2.5" exit. I forget where it came from.Now I don't have to worry about emissions and its an easy project for the apes, thought I'd get them to stick a 3" straight through pipe together. Question is do exhausts make much difference on turbo motors, , especially over such a short length? That fan the gasses hit must cock things right up from the start!

Chris

On my little car I run a 3" pipe all the way even though the turbo has a 2" exit, this runs at 102db, if I need to run below this I have 12" of 2" perforated tube with wadding that goes up the tail pipe so effectively adding a 2" restriction at the end.

When this is in place it is noticeable that it is down on power, the top end is slightly stifled.

Regards Mark

[Edited on 12/12/15 by mark chandler]

Any back pressure on a turbo exhaust system can degrade performance (e.g. spool time, maximum boost), so it's important for it to be as free flowing as possible. Gas velocity isn't an issue downstream of the turbo, which is why you see huge 3+" systems used on high power GTRs etc.

Yeah larger is, within reason, always better with tubby engines.

Best gains tend to depend on the engine in question, but try to concentrate on keeping diameters matched and blending the wastegate flow in smoothly further away from the turbine rush oem would.

[Edited on 12/12/15 by coyoteboy]