Distinguish, differentiate, compare and explain what are the differences between Petrol and Diesel Engines.
Differences between Petrol and Diesel Engines
- In petrol engine, fuel used is Petrol, so high self ignition temperature desirable. In diesel engine, fuel used is diesel oil and s0 low self ignition temperature desirable.
- In petrol engine, basic cycle is based on Otto cycle. Diesel Engine are based on diesel cycle.
- First one requires an ignition systems with spark plug in the combustion chamber while in other self ignition is due to the high temperature, caused by high compression of air, when fuel is injected.
- In petrol engine, fuel and air introduced as a gaseous mixture in the suction stroke. Carburetor is necessary to provide the mixture. Throttle controls the quantity of mixture introduced. In diesel engine, fuel is injected directly into the combustion chamber at high pressure and at the end of compression stroke. Carburetor is eliminated but at high pressure fuel pump and injector necessary. Quantity of fuel regulated in pump.
- Petrol engine has higher maximum revolution per minute r.p.m. due to higher weight.
- In first, compression ratio is between 6 to 10.5. Upper limit of C.R. is limited by antiknock quality of fuel. In the second one, compression ration is between 14 to 22. Upper limit of C.R. is limited by the rapidly increasing weight of the engine structure as the compression ratio is further increased.
- Diesel engine are much heavier due to higher pressure.
- Maximum efficiency of petrol engine is low due to low compression ratio whereas diesel engine has higher maximum efficiency due to higher compression ratio.