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patkeefe patkeefe is offline
one of the great unwashed
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Join Date: Apr 2004
Location: Ringwood, NJ
Posts: 2,850
The secret is to maximize the charge in the cylinder. There are a million combinations to do this. Also, at low RPM, I suspect a 930 has about the same CR as a VW 1300 engine. Efficiency is a function of CR, with the caveat of maximized charge.
I suspect SC cams decrease the parasitic losses in the induction system, and thus increase the efficiency at low to mid in the 930 powerplant. I also suspect that when not making boost, the compressor wheel is just a restriction in the path of the air going to the cylinders.
I run DC-20 cams, but I have a turbo SC engine, with static CR of 8.5, and boost limit at 5.8 PSI.
I also firmly believe that the factory considered possible warranty issues with the 930, and made it rather tame for production.
Patrick E. Keefe
78 SC
01 Boxster
Old 01-31-2010, 09:37 AM
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