moper said

Static ratio is fine. The trick is finding the cam with the closing event you need to get the dynamic down to no more than 8.5:1 and fit your Magnums' lift limitations.
That might be worth talking to Scott Brown or a custom grinder. (rather than talking to Comp's tech guys who can be ignorant of the details)

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blue missile said

Octane,

According to the gasoline refiners association the numbers are as follows:
Based on real or “dynamic” compression ratios 7:1req 87 octane, 8:1 req 92 octane, 9:1 req 96 octane. These numbers are based on an engine with a carb and no engine management system.
Based on that, extrapolated numbers are as follows:
7.0:1=87 octane
7.1=87.5
7.2=88
7.3=88.5
7.4=89
7.5=89.5
7.6=90
7.7=90.5
7.8=91
7.9=91.5
8.0=92
8.1=92.4
8.2=92.8
8.3=93.2
We happen to have 93 octane here in Texas but to be safe 92 is offered nation wide.
I think your best bet is to revisit the cam, as others have said the timing events are the easiest way to manipulate the DCR. With 92 octane gas 8.0 will be fine. If you are close to the edge consider some thermal management with coatings, that can be self applied to the valve faces and the combustion chamber.
Andrew

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