kc8oye Posted December 28, 2010 Share Posted December 28, 2010 A guy on another forum explained how to calculate static compression for my engine.. so I figured I would share since it's simple and easy to follow My pistons are SpeedPro L2256F +.030 here's their info from summitracing.com Bore (in) 4.000 in. Piston Style Flat top, with four valve reliefs Piston Material Forged aluminum Compression Distance (in) 1.563 in. Piston Head Volume (cc) +6.10cc Let's just go through it for the benefit of others reading here. A 350 bored +0.030" will have a bore of 4.030" and a stroke of 3.480". Using our cubic inch formula of .7854 times bore times bore times stroke times 16.387 = 727.4 cc's. The stock 350 crank will have a radius of 1.740" (half the stroke). The stock rod length will be 5.703". Your pistons have a compression height of 1.563". If we add up these values, we find a stack of 9.006". Now, given that the nominal block deck height of a 350 is 9.025", that would theoretically put the piston crown at 0.019" below the deck at TDC. We would use the same formula to figure the piston deck height volume. .7854 times 4.03 times 4.03 times .019 times 16.387 = 3.97 cc's. Let's say we have 67 cc chambers in the heads. And we know that the pistons you are using have 6.1 cc's in the crown. 727.4 in the cylinder 67 in the heads 3.97 in the piston deck height 6.1 in the piston crown 9 in the gasket (generic 0.040" gasket) total- 813.47 total less cylinder- 86.07 divide larger by smaller = 9.45:1 static compression ratio. Quote Link to comment Share on other sites More sharing options...
amsterdam84 Posted December 28, 2010 Share Posted December 28, 2010 If I was as handy with html as I used to be I would think a web calculator on this site would be very nice to have. Might have to play around a bit. Maybe I could make something. Quote Link to comment Share on other sites More sharing options...
kc8oye Posted December 28, 2010 Author Share Posted December 28, 2010 i could probably do it too if someone told me what language to do it in Quote Link to comment Share on other sites More sharing options...
Sam (Bones) Posted December 29, 2010 Share Posted December 29, 2010 or you could just bookmark this page Quote Link to comment Share on other sites More sharing options...
Mike 57 Posted December 29, 2010 Share Posted December 29, 2010 I was thinks the same thing Sam! Quote Link to comment Share on other sites More sharing options...
kc8oye Posted December 29, 2010 Author Share Posted December 29, 2010 yeah..b ut then it's not the FGMCC's calculator... Quote Link to comment Share on other sites More sharing options...
kc8oye Posted December 29, 2010 Author Share Posted December 29, 2010 and the next evolution going to 64cc vortec heads takes me to 9.75:1 which I think is tolerable on pump gas... maybe.. Quote Link to comment Share on other sites More sharing options...
Sam (Bones) Posted December 30, 2010 Share Posted December 30, 2010 that's close with iron heads Quote Link to comment Share on other sites More sharing options...
kc8oye Posted December 30, 2010 Author Share Posted December 30, 2010 yeah kinda what I Was thinking sam. Quote Link to comment Share on other sites More sharing options...
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