Quote:
Originally Posted by TurboKraft
One result of this mis-matching is higher exhaust backpressure at the turbine inlet (header) flange. 930s are bad enough, and the long, undersized tube feeding the wastegate on most aftermarket headers doesn't help matters, either.
Anyone else have exhaust backpressure data they would like to share?
We just dyno tuned an ex-Ruf 3.4L that had been in storage for many, many years. Another shop converted it to EFI and "600hp" -- not with a K29-7006#13, buddy! At 17.2psi boost in the manifold, the exhaust backpressure was just a hair under 30psi. About a 1.75:1 pressure ratio (backpressure:boost) despite the larger #13 turbine housing. Car is choking on the backpressure, spooling up slowly, keeping the Group B cams from doing their work.
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Perhaps a little off topic but I'm curious...
Would a larger diameter header (say from the standard 1 5/8" to 1 3/4") help to reduce the backpressure? Or is it something else?
thanks!