what exactly is engine knock

[LaZaBLuEMp3]

i know its a stupid question, but im not totally sure on what it is

[JasonH]

Engine knock is more accurately called "pre-ignition" or "detonation". It's when the fuel and air mixture ignite before the piston reaches the top if its stroke. If the engine is too hot, the fuel octane is too low or the combustion chamber pressure too high (or any combination of the three) you'll get engine knock.

P.S. - It's not a stupid question. Far from it.

[LaZaBLuEMp3]

ok thanks. one more question. what does it feel like in the car? does it make a sound or something?

[LinuxRacr]

When it is audible, it sounds like someone is rolling dice under the hood. It is not always audible. If you hear snap, crackl, pop...you have a problem on your hands..

[DooMer_MP3]

I always loved the description as "somebody playing craps under your hood", LOL! :D.

Chris