What is detonation?

What is detonation?

Detonation :

At present the amount of power that can be developed in the cylinder of a petrol engine is fixed by the liability of a fuel to detonate, just before the flame has completed its course across the combustion  chamber and remaining unburnt charge fires throughout its mass spontaneously without external assistance.

The result is a tremendously rapid and increase in pressure which sets up pressure waves that hit the cylinder walls with such violence that the walls emit a sound like a ping. It is the ping that  manifests detonation. Thus a very sudden rise of pressure during combustion accompanied by metallic hammer like sound is called detonation.

The region in which detonation occurs is farthest removed from the sparking plug , and is named the detonation zone and even with severe detonation this zone is rarely more than one quarter the clearance volume.