Anyone know much about turbo's. I am currently re-engining my kitcar/replica with a Subaru Impreza turbo motor. The Subaru has a turbo with an integral wastegate next to the turbo's exhaust outlet.

Looking at the attached picture which would be better for the turbo downpipe, a downpipe where the wastegate gases are divorced for a distance or one where they they are merged immediately.



Cheers
Guy

 

merged
as the others can cause boost creep

 

Well they both exit the same way, so no real reason to run two separate pipes.

 

open mouth 1

 

I have a split down pipe (not as long as one in your pic though) and no probs on boost creep, even at max 1.65 bar on hybrid turbo! Decent mapper (like Bob) can do magic anyway.

 

Ive got a divorced pipe on mine what is the reason for the twin pipe???
kips

 

On the two you show, there is unlikely to be a lot of difference in terms of performance. Personally, I would go for the open mouth design. The problem with the separate waste gate pipe comes when the WG pipe merges back in to the main gas stream too early.

 

Hi Harvey, how's the 600 bhp monster doing with the help of Bob?

I can see the problem here, the WG gas flow ends up with back pressure on the actuator since its not able to clear the pipe, this then causes boost creep? Mine is split and about 10 percent shorter on length than the one in the picture but must admit I've not had boost creep issue, well, glad to say really!

 

Hi guys thanks for the replies, as an aside to my original question.

If the wastegate was divorced off as below with a divider between wastegate & exhaust outlet to seperate them completely. Could I run a totally seperated exhausts for wastegate and exhaust itself. If so would there be any postive or negative side effects.

 

suppose that would be like having a huge long screamer pipe ! dont see any reason for you to do that actually ? might cause probs but i havent heard of any one doing that !