compression ratio vs octane

Andrew, cool post... Thanks. There is a dynamic compression ratio calculator at KB-Silvolite.com that i use a bit. In terms of the DCR vs octane, the only time that might be really accurate is if the fuel is.... Pump gas is a bit less precise. I build for use with 89 octane.. Around here that's 10% ethanol too, and it accounts for things like liars and mixups where the high octane is contaminated or simply not what is advertised. You know the factors that effect the DCR. Those are rod length, stroke, intake valve closing event, and mechanical(static) compression ratio. To that end, with the rod ratios and typical stock strokes, I've run 185psi pretty easy on pump 89 with open chamber iron heads using the stock 383 HP camshaft. So I'd say it's more than strictly math. You can "fool" the engine into thinking the fuel is better by using quench, and chamber design, and piston shape, and good porting to enhance wet flow into the chamber. Also the longer strokes available make the pressure rise faster, and allow for much less initial timing.