Chemistry

What is the difference between Petrol and Diesel Engine?

petrol engine Vs. Diesel engine

The major difference between petrol and diesel engine is that the Petrol engine works on the otto cycle i.e. on constant volume and less power is produced due to less compression ratio while the diesel engine works on the diesel cycle i.e. on constant pressure with high compression ratio and high power.

Difference between Petrol and Diesel Engine in Tabular Form

Petrol EngineDiesel Engine
A petrol engine draws a mixture of petrol and air during the suction stroke of the engine.A diesel engine draws air only during the suction stroke.
high burning cost as petrol is expensive. low burning cost as diesel is cheaper.
the pressure is 10 bar at the end of compression.the pressure is about 35 bar at the end of compression.
It works on the otto cycle. It works on Diesel Cycle.
The highest speed of the engine is about 3000 RPM.the speed is about the range of 500 to 1500 RPM from medium to the low engine.
the petrol engine is Less costly.the diesel engine is costlier.
Petrol is a primary fuel.Diesel is the primary fuel.
the petrol engine easier to start even cold weather too.in cold weather, the diesel engine is difficult to start.
thermal efficiency is lower because of the lower compression ratio. due to the high compression ratio, thermal efficiency is high.
maintenance cost is less.maintenance cost is high.
the carburettor is employed to mix air and petrol in the required proportion and is supplied to the engine during suction stroke. the injector or atomiser employed to inject the fule at the end of combustion stroke.

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