Quenching

Quench is achieved when the piston comes within very close proximity (I believe within .040") of the combustion chamber surface at TDC. It is usually done by using flat-top zero-deck pistons and "closed chamber" heads. This causes the compressing intake charge in the cylinder to be squeezed violently into one part of the chamber, imparting a huge amount of turbulence to the intake charge; this greatly reduces the chances of detonation during compression and allows you to run a higher static compression ratio with lower octane pump gas. There are a few members on here running around 10.5:1 compression with iron closed-chamber heads on 87 octane pump gas! Of course, you already know the more compression you have the more efficient your engine will be (more power and better gas mileage).