Simple Exhaust Questions

RotaryProphet · 10-03-2008, 07:34 AM

It does seem wasteful to go from 2.5" to 3"... with that bottleneck in there, there's either not going to be nearly enough flow to justify a 3" pipe, or there will be enough, but you'll have some serious backpressure issues in the manifold pre-turbo. Finding a T3 to 3" adapter might help, but it really depends on the size of the turbo itself.

Is it a real T3? Because they're very small turbos for a 13B, even on the smallish size for a 12A, really. Even a hybrid T3/T4 is going to have the smaller T3 exducer, which is bound to create a huge flow restriction unless you're running low boost (6 psi as a guesstimate, you'd need an exhaust backpressure gauge to find out where your "max" is) and have a large external wastegate which dumps back into the downpipe.

10-03-2008, 07:34 AM	#1
RotaryProphet Rotary Fanatic Join Date: Sep 2008 Posts: 147 Rep Power: 17	It does seem wasteful to go from 2.5" to 3"... with that bottleneck in there, there's either not going to be nearly enough flow to justify a 3" pipe, or there will be enough, but you'll have some serious backpressure issues in the manifold pre-turbo. Finding a T3 to 3" adapter might help, but it really depends on the size of the turbo itself. Is it a real T3? Because they're very small turbos for a 13B, even on the smallish size for a 12A, really. Even a hybrid T3/T4 is going to have the smaller T3 exducer, which is bound to create a huge flow restriction unless you're running low boost (6 psi as a guesstimate, you'd need an exhaust backpressure gauge to find out where your "max" is) and have a large external wastegate which dumps back into the downpipe.