aluminium head questions

You can approach 12:1 on pump gas with aluminum heads and a well thought out quench motor. Because the aluminum heads dissipate heat so well, you can get by with a good bit more compression. Couple that with using a good closed chamber design and a properly set up quench short block and a well thought out camshaft and you might could get to 12:1 on pump premium. With that much compression on a quench motor and good flowing heads, you'd certainly eclipse 500 HP.