05-09-2013, 08:23 PM
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Senior Club Cobra Member
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Join Date: Jan 1999
Location: MARKSVILLE,LA.,,
Posts: 3,235
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Neutral
if you mean cylinder pressure as in cranking the engine over with a compression tester in the spark plug hole,then the answer is no.........
Your cam overlap or lack there of will make a huge difference in the actual cylinder pressure and not have anything to do with the compression ratio.....
example, I checked the compression on 2 different freshly rebuilt 351-W's.
engine #1 barely showed 125 pounds when cranking, but had a cam in it that had a split duration and a lot of overlap,this one calculated out to 10.4 to 1 compression........
engine #2: pretty much a standard rebuild, stock 351-W cam has approx. .375 lift, this engine had a cam of only .415 lift, no overlap and was not a split duration camshaft....cranking pressure was 150+ psi and the calculated compression ratio was only 9.7 to 1.........
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DAVID GAGNARD
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