is going to big of an exahust for a turbo car pointless? anything over 3 inch. the turbo outlet is only 2.5 big but i have a bnr stage 3. i currently have a 2.5 inch exahust and i cant build high boost.

 

if you have a large turbo, then you will want something 3" or above! Some guys run 3.5 to 4. But with your size turbo you dont need anything huge.

 

ok to4b 60-1 just to make sure......

 

I've always heard if you have a turbo. the bigger the exhaust. the better,

 

3" would be a better size, you need the low compression behind the turbo. its diff from NA engines IIRC.

 

I was told by an old school rotary guru that 3 inch is good for a TII

 

Cant build high boost, how high are you getting? What kind of wastegate are you using?

 

There is such a thing as too big an exhaust on a turbo car, or any car for that matter.

 

Yes, there is. With a non-turbo car, there is an ideal exhaust velocity to obtain maximum scavenging from the cylinders/chambers (and best efficiency/power). The smaller the pipe, the lower this peak occurs. Hence econoboxes with tiny exhaust systems - they're hitting ideal flow rates right around normal cruise. An insanely big exhaust system on a NA will just leave you with less low end torque and generally an unhappy engine.

For a turbo, the only factor is pressure differential over the turbo. The ideal case is the turbo venting to atmosphere. The exhaust system here is just a convenient way to route fumes through some baffling and out the back. There's no such thing as too big for performance, but there is a point of diminishing returns.

-=Russ=-

 

and the weight factor of carrying around a 5" sewer pipe sticking out the back of ur car

 

hmm ill try for 3 to 3.5

 

*DING*DING*DING*
We have a winner!
Lower pressure on the back side is always better. It's the only reason a turbo works in the first place.

 

downpipe with a exhaust runner tube... around 26inches....