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RarlyL8 RarlyL8 is offline
Crotchety Old Bastard
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Join Date: Jan 2000
Location: Huntsville, AL
Posts: 13,614
Turbos produce power using heat and velocity. Heat is easy, it is velocity that I fucus on. This is covered well in Corky's book. The primary internal diameter must be matched to the ports and the application. Too big and you lose velocity (increase lag) but increase top end HP capacity (huge turbo airflow). Match the primaries to the ports and you optimise off boost torque and reduce lag. We use merge collectors to further optimise the flow transition toward the turbo. The path is continually restricted until it reaches the turbo flange where all the energy is focusted.
I have posted dyno graphs of short tube versus tuned headers when we were testing these headers. Controlling boost creep was thrown in the mix as well due to the poor design of the elephant nose waste gate circuit of the short tube headers. That muddied the water a bit as more boost equals more power. I'll look up the graph.
RarlyL8 Motorsports / M&K Exhaust - 911/930 Exhaust Systems, Turbos, TiAL, CIS Mods/Rebuilds
'78 911SC Widebody, 930 engine, 915 Tranny, K27, SC Cams, RL8 Headers & GT3 Muffler. 350whp @ 0.75bar
Brian B. (256)536-9977 Service@MKExhaust Brian@RarlyL8
Old 05-10-2014, 07:45 AM
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