Compression
03-13-2007, 04:45 PM
#1
5th Gear Member
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Join Date: Sep 2005
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Compression
hey i just downloaded an engine compression ratio calculator from fordstrokers.com and put in 408w, 4.030 bore, 4.000" stroke, 6.125" rods, 212cc comb. chamber (as refered by some of you), .04" gasket, 4.030" gasket diameter and flattop pistons and got a CR of only 4.8:1
i was looking for something more in the 10-11.5 range, and by adjusting the combustion chamer size i found that the only way to do that is to get a 70-85 cc combustion chamber... is this thing wrong, did i put something in wrong, or am i just ****ed for compression?
i was looking for something more in the 10-11.5 range, and by adjusting the combustion chamer size i found that the only way to do that is to get a 70-85 cc combustion chamber... is this thing wrong, did i put something in wrong, or am i just ****ed for compression?
03-13-2007, 05:03 PM
#2
6th Gear Member
Join Date: Sep 2005
Location: Hamilton, NJ
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RE: Compression
212CC ??? [sm=alcoholic.gif][sm=icon_rofl.gif] Who the f*ck told you that ?!? LoL Thats WAAAAAAAAAAAAAAAAAAAAAAAY wrong. 70cc sounds more like it... that sounds toobig though... depending on pistons, gaskets, etc. try something smaller.
03-13-2007, 10:43 PM
#6
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RE: Compression
okay next question... now its too high
http://www.camshaftinnovations.com/SBF212.htm
those are the heads im lookin at
i used the 65cc chamber and changed the bore to 4.060" cause thats what those heads are made in and now i have a 12.5:1 ratio... am i going to be able to feed it pump gas?
http://www.camshaftinnovations.com/SBF212.htm
those are the heads im lookin at
i used the 65cc chamber and changed the bore to 4.060" cause thats what those heads are made in and now i have a 12.5:1 ratio... am i going to be able to feed it pump gas?
03-14-2007, 10:15 PM
#10
2nd Gear Member
Join Date: Jan 2007
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Posts: 213
RE: Compression
No, you wont be able to run 12.5:1 on pump gas. The maximum compression ratio you can run will be determined by your total combination. Not only do you need to know your bore, stroke, rod length and the heads you'll be using,you'll also need to know which camshaft. Once you know these things then any experienced engine builder could recommend the best compression ratio for your combo.