Compare and contrast CI and SI engines Compare and contrast

Solution

S.no Aspect Spark Ignition Engine Compression Ignition Engine 1 Fuel used Petrol is used as fuel, which has high self ignition temperature Diesel is used as fuel, it has low self ignition temperature. 2 Cycle operation SI engine works on otto cycle. CI engine works ondiesel cycle. 3 Cycle efficiency SI engines have low thermal efficiency CI engines have high thermal efficiency. 4 Engine speed SI engines are high speed engines. CI engines are low speed engines. 5 Constant parameter during cycle Constant volume cycle Constant pressure cycle. 6 Time of knocking Knocking takes place at the end of combustion. Knocking takes place at the beginning of combustion. 7 Volume to power ratio SI engine is low CI engine is high 8 combustion Carburettors are used in SI to prepare the air - fuel mixture CI engines fuel at high pressure is injected at the end of compression stroke 9 compression ratio SI engines is small CI engines the  is higher 10 harmful due to the pre-detonation SI is more    CI is less