Compare Petrol engine with Diesel engine with each other

(i) Basic cycle: Petrol Engine work on Otto cycle whereas Diesel Engine work on diesel cycles.

(ii) Induction of fuel: During the suction stroke in petrol engine, the air fuel mixture is sucked in the cylinder while in diesel engine only air is sucked into the cylinder during its suction stroke.

(iii) Compression Ratio: In the petrol engine compression ratio in the range of 5:1 to 8:1 while in diesel engine it is in the range of 15:1 to 20:1.

(iv) Thermal efficiency: For the similar compression ratio, the thermal efficiency of diesel engine is lower than petrol engine.

(v) Ignition: In petrol engine the charge (A/F mixture) is ignited by the spark plug after the compression of mixture while in diesel engine combustion of fuel due to its high temperature of compressed air.