CR and pump gas question

I think there has to be value to using material that keeps the combustion chamber cooler just based off the way combustion and detonation work. Whether the benefit of switching from iron to aluminum alone is even enough for a tiny bit of measurable benefit is up for debate, but the concept has got to be accurate. I think the idea that "aluminum heads can handle higher compression ratios than iron" comes from all the improvements of a standard aftermarket aluminum head over the factory irons, though - material being just one part of it. Again, how much that part is I've got no clue. Could be an immeasurably small amount, could be a lot.