Turbo setup with open exhaust, still bad low end?

[sniper]

With NA motors i know that if you have a totaly open exhaust you will lose low end torque, is it the same for a turbo setup? Would there be lots of lag on the bottem end or would the turbo be able to spool faster?

 

[JBrady]

Generally speaking it is hard to put to "open" of an exhaust on a turbo. It is also hard to put too large of an air inlet pipe on a turbo. The compressor and turbine sections on turbochargers separate and completely change the dynamics of the inlet and exhaust tuning.

That said, back in 1990, I installed a 3" pipe on my Ford 2.3 liter turbo engine in my 1987 TBird Turbocoupe. Boost response improved as did all around drivability. A co worker with a near identical TBird tried a 4" pipe and claimed it lost low end. I never drove the car but he did change out to a 3" pipe and said it was better. I am not certain if his observations were even accurate. On a turbo engine I would be more concerned with manifold design.

 

[Pro]

the turbo provides enough 'back pressure' (and please don't crucify me for using that term - i hate it myself. there's so much more to low end response than 'back pressure'...) or exhaust scavenging thanks to the spinning turbine to eliminate any concerns about lost low RPM driveability. in any case, the differences will be negligible, and well worth it for the power gains above it.

but the drone.....well, that's something else entirely.