CR and pump gas question

Ok what the hell, I give this a try.
So we all know that atomized fuel will detonate at X temperature while at X pressure. I have no idea what the real numbers are. So if our mythical combo generates temperature and pressure that are very close to both of the x’s small environmental variances can cause detonation. Burr in the chamber ect. We have one with aluminum heads and a completely identical iron head. Aluminum transfers heat to the coolant quicker than iron. Heat is something, molecular movement, cold is just the absence or reduction of molecular motion. If heat is transferred from the chamber to the coolant faster with aluminum the chamber will be cooler. If the combo is close enough to the x’s that the difference in chamber temperature matters, well there you go. If it sheds heat quicker you can put more in it before the aluminum gets to the x’s. HOWEVER, there is no such thing as two identical heads. One aluminum, one iron. Chasing unicorns! An aluminum head will take more compression than an identical iron head. It just physics...............but wait is that a UNICORN!