drewmcinnes Posted November 28, 2011 Report Share Posted November 28, 2011 Ok so I'm rebuilding my 4k and have 5k pistons (8cc volume) pistons. Just wondering if any one can point me in the right direction to what my compression will be. Head is a ke70 4k head. Hope this is enough info. Thanks in advance Quote Link to comment Share on other sites More sharing options...
Evan G Posted November 28, 2011 Report Share Posted November 28, 2011 wait wtf? are you trying to put 5k pistons in a 4k? or a 4k head on a 5k block? Quote Link to comment Share on other sites More sharing options...
Des Posted November 28, 2011 Report Share Posted November 28, 2011 He is trying to make a 1500cc 4k. Quote Link to comment Share on other sites More sharing options...
Evan G Posted November 28, 2011 Report Share Posted November 28, 2011 ah i see, *awaits altezzaclub reply* Quote Link to comment Share on other sites More sharing options...
altezzaclub Posted November 28, 2011 Report Share Posted November 28, 2011 lol! thankyou Evan! "Flat top" or "O-dish" 5K pistons have about a 5cc dish in them. Your stock 4K head combustion chamber is about 31cc, gasket about 7.5cc. Motor is 80x73 now isn't it, = 367cc. So you have (367+7.5+5+31) going into (5+7.5+31) or 410.5:43.5 or 9.4:1. Not high because the dish in the piston is 15% of the head volume. A real flat top piston would be (367+7.5+31) into (31+7.5) or 405.5:38.5 = 10.5 to one! Measure a piston dish for volume and make sure! Quote Link to comment Share on other sites More sharing options...
drewmcinnes Posted November 28, 2011 Author Report Share Posted November 28, 2011 Thanks guys I'll measure the piston Quote Link to comment Share on other sites More sharing options...
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