compression ratio and horsepower

Old 12-27-2009, 07:31 PM
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chevyart
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Default compression ratio and horsepower

say you have a real healthy sbc with the good heads and cam and intake etc and you eith add or subtract a point of compression. how much hp is lost or gained with each 1 point change of compression ratio. would appreciate help in understanding what a change will make on my engine thanks chevy art
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Old 12-27-2009, 07:41 PM
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cam67152
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It's usually 2-3% per point in compression between 9-12 but I think it drops down to 1-2 above 13:1 this is assuming your using the same cam. your obviously going to make alot more power if you use a cam that is matched to a higher cr.

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Old 12-28-2009, 12:05 AM
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russ67chevelle
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complicated, correct though, its like this going from 9 up a point is say worth 5 percent.going from 10 up a point might only be worth 4 percent.going from 11 up a point might be only worth 3.5 percent....get it?
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Old 12-28-2009, 12:48 PM
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poboyracin
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This is a pretty good article by David Vizard that does a good job explaining what happens in "theory" with compression changes.

http://www.popularhotrodding.com/eng...eze/index.html
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Old 12-29-2009, 08:37 PM
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chevyart
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Default compression ratios

thanks guys for the response. before i saw the chart i understood how it worked from the frist two posts and the chart gave more final figures. now i know how this works and will use it in the future chevy art
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