The compression ratio isn’t just a number: it’s one of the greatest determining factors in engine building. Compression ratio determines the type of fuel, how much boost, and has a significant ...

The guys at Muscle Car Review show you how to check engine compression with the latest tools. Check it out only at hotrod.com or the October 2011 issue of Muscle Car Review Magazine.

We explore why a higher compression ratio means more power for your hot rod, and explain what to do to maximize that bump in power.

A high compression ratio means you're squeezing tightly on the air-fuel mixture in the engine's combustion chambers, which in turn means more power and fuel efficiency.

Why variable compression ratio matters Today's gasoline-engine cars compress the outside air to about a tenth its original volume, a 10:1 ratio, inside each cylinder.

But too high a ratio causes knocking—premature detonation of fuel-air mixture during the engine's compression stroke caused by high cylinder temperatures.

CHECK OUT: Audi looks back at 40 years of 5-cylinder engines When you want power, the compression ratio drops and the turbocharger makes use of more boost.