DCR help
12-27-2011, 12:56 PM
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DCR help My cam has a 42 degree ABDC closing point on a stock bottom end LS1 with 62cc heads and a stock thickness head gasket. I plan on switching to some AFR 230s and I'm wondering if I can run anymore compression on 91 pump gas.
12-27-2011, 04:27 PM
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Your SCR now should be around 11:1 and with a DCR of around 9.26
Your SCR with AFR 230s(small bore 65cc) should be around 10.6 and a DCR of around 8.92. 91 octane will be kinda on the edge with your 9.26, so an additive might be in order. A REALLY good tuner can do wonders, so invest the money/time on finding the right one to keep the engine away from harmful detonation.
Your SCR with AFR 230s(small bore 65cc) should be around 10.6 and a DCR of around 8.92. 91 octane will be kinda on the edge with your 9.26, so an additive might be in order. A REALLY good tuner can do wonders, so invest the money/time on finding the right one to keep the engine away from harmful detonation.
12-27-2011, 07:17 PM
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I am under the opinion that actual pressure (cranking pressure) is a much more accurate number to use. This is "Real World" information not just a mathmatical ratio. I have seen several posts where guys are running 190-200 psi cranking pressure and some are doing more on pump gas. Combustion chamber design and quench area have a notable impact on what can be tolerated with pump gas. AFR heads are suppose to have an excellent chamber design. This calculator will give you both pressure and DCR... http://www.wallaceracing.com/dynamic-cr.php