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copbait73 copbait73 is offline
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Join Date: Nov 2003
Location: Chesterfield IN
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Yesterday I was playing on a Turbo calculator website. I put in the factory data for the '77 930 Turbo motor (no guessing the intercooler eff.). I was somewhat surprised to find the assumed VE had to be dropped to only 75% to make all other knowns work.

Obviously this is low for a performance design like the 911. It shows how much was left on the table to meet all other requirements like emissions, fuel economy, noise, etc while still producing more power reliably. In many ways a diamond in the rough compared with say the MFI 2.7RS.

This exercise also shows expensive hardware only marginally improves HP with no changes to improve VE. The best turbo and best intercooler will add little compared with good old basic hot rodder VE improving techniques of intake tune and balance, port/valve sizing (flowing), cam timing/lift and exhaust tune and balance.

This does not say the most efficient compressor and CAC are not extremely important. They are, after the high VE gets that charge in it needs to be cool not simply a high BOOST pressure.
Old 01-17-2010, 02:18 PM
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