CR and pump gas question

famous bob said

Aluminum carries off heat faster than cast iron, helps with cooling the combustion chamber, there fore allowing more compression w/o using a higher grade octane , '' to a certain extent !" No way could I run 10.5 to 1 with cast iron heads on 91 , and have it tuned for all out h.p. Not sure on that tho, still tuning----.

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I guess you're right. I've run iron '906 heads at 11.9:1 on 91 octane for maximum horsepower and never been able to make any more than 748 HP at our home dyno. I thought we were gonna make more on Comp Cams dyno, but the dyno operator forgot to turn the water on to the engine and we had to run a blown up engine, with bent valves and 56% leakdown, that only made 730 HP there.