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Old 07-31-2012, 02:54 AM   #81
serialk11r
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Garage
Quote:
Originally Posted by Coheed View Post
there are "twinscroll" divided entry housings available out there I've used the .78, .82, and 1.06 housings on a divided GT3076r. The results? Monster response in the mid-range, gains of 40lbft at 5000rpm, with a 10% loss up top.

It isn't worth it overall. The small turbine gets choked powering the larger compressor, and the divided housings don't flow nearly as well as their open-counterparts. For response, the twinscroll stuff is pretty good. But to be honest, I prefer the top end rush the open housings give. The engine just seems smoother and makes more power on less boost with the open housings.
Increase the size of the turbine slightly, and match the turbine inlet area? If you say the top end loses power, then part of that response gain is coming from the increased exhaust gas velocity (and thus backpressure).

Twin scroll allows more efficient exhaust wave impulse transfer to the turbine, "all else being equal" (in this case I mean how restricted the turbine is).
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