Technical the pain of to much compression

Every online calculator I've seen does not specify "which" IVC, but it's IVC when the valve is fully closed where lifter transfers from the flank to the base circle.. The problem is that most cam manufacturers give the IVC value at .050" lift, which occurs sooner in the engine cycle and makes the DCR seem higher than it really is. Crane (at least for some of their cams) lists IVC at .004" lift, which is very close to the actual full closing and will give you a more realistic DCR.
When I talk to the cam grinder, I ask for the IVC when fully closed (not at .050"). Then I punch that IVC value into an online calculator while I simultaneously ask him to tell me the DCR value he gets. The results are pretty close.

I run a 351 Cleveland with open chamber heads in my '31 coupe. Conventional wisdom says you can't run those heads on pump gas if it's over 9.1 SCR. But I'm running 9.75:1 SCR on 87 octane with nary a ping. How? Because my custom cam was cut with all other vehicle parameters in mind and has an IVC that gives 7.4:1 DCR.

Custom Cams are worth every penny.

 

Meth injection was used in WWII for poor gas Quality and octane by British and Germany

 

So the consensus seems to be aluminum's higher heat transfer properties, leading to reduced temps and/or hot spots in the combustion chamber, right? OK. Thanks guys. I wonder, does anyone have links to any technical papers (SAE for instance) or articles (Hot Rod, others) that discuss this?

 

David Freiburger when he was editor I think it was Car Craft did some dyno test on some of the hot rod truths all on a SBC two I remember port matching If the cylinder head ports were bigger than the intake ports there was no power gain. and the other was aluminum vs iron heads and compression on a 10.5 engine and could not see a difference. This was done on just this one combination.

 

My engine shop told me the same, but also warned me that aluminum heads also mask detonation. He said you might have detonation and not hear it with aluminum heads like you can with cast iron. So it's possible to be destroying pistons through detonation with aluminum head engines and not hear it until it's too late.