What are the effect of Detonation in I.C. engine?

 Detonation in I.C. Engines

The loud pulsating noise headed within the engine cylinder of an I.C. engine is known as detonation (also called knocking or pinking). It is caused due to the propagation of high speed pressure wave created by the auto-ignition of end portion of unburned fuel. The blow of this pressure wave be of sufficient strength to break the piston. Thus, the detonation is harmful to the engine and must be avoided. 

The following are certain factors which causes detonation:-

1. The shape of the combustion chamber.
2. The relative position of the sparking plugs in case of petrol engines.
3. The chemical nature of fuel.
4. The initial temperature and pressure of the fuel.
5. The rate of combustion of that portion of the fuel which is the first to ignite. This portion of the fuel is hearing up, compresses the remaining unburnt fuel, thus producing the conditions for auto-ignition to occur.

The detonation in petrol engines can be suppressed or reduced by the addition of a small amount of lead methode or ethyl fluid to the fuel. This is called doping.

The following are chief effect of detonation:- 

• A loud pulsating noise which may be accompanied by a vibration of the engine.
• An increase in the heat lost to the surface of the combustion chamber.
• An increase in carbon deposits.