Quote: The guys here will correct me if I'm wrong, but I think it's not that aluminum lowers compression, but more like you can run more compression with aluminum than an iron head without detonation, all things being equal.
This is what everything points to .
Coke , with pistons that deep in the hole you'll have no issues with piston to valve interference. but you'll want to be careful with compression being too high without the benefit of quench because of how deep they are in the hole.
