Knocking is one of the unwanted phenomena takes place in the compression ignition engine. It has number of bad effects on the engine life and performance. If ignition delay is long, more fuel is accumulated in combustion chamber and burning of fuel produces more rate of pressure rise, resulting in more forces on the piston. Properties of fuel like viscosity, compression ratio etc. affect the knocking and hence engine performance and exhaust emission. Knocking is also affected by intake Temperature and auto ignition Temperature of the fuel. If fuel Temperature is high, then ignition delay period will be reduced and the performance of engine will be improved In the present work fuel is heated to different temperature as 30oC, 35oC, 40oC, 45oC, 50oC, 55oC, 60oC. Compression ration is maintained at 17.5. Result is found out at different loads. 50oC temperature has given optimum results with concerned of performance and exhaust gas.

Keywords : Fuel Preheating, Knocking, Ignition Delay, CI Engine.