Difference Between Diesel Engine And Petrol Engine


Both petrol and diesel engines have the same mechanism. Both of them can be two-stroke or four-stroke , both have a cylinder , a piston , a piston pin , a connecting rod , a crank and a crank shaft but there are many differences between the two

Diesel Engine Petrol Engine
The mechanism of diesel engine involves that only air is supplied into the cylinder which is compressed during the compression strokes . At the end of the compression the air reaches to a very high temperature and fuel is injected in the form of fine spray by a nozzle. The mechanism of petrol engines involves that a mixture of air and petrol is injected into the cylinder . The mixture is produced by the carburetor . This mixture is compressed inside the cylinder during compression stroke . After the compression , a spark plug produces a spark that leads to combustion of the mixture .
Compression Ratio in diesel engine is as high as 24 Compression Ratio in petrol engines is below 12 . It is due to the phenomenon of knocking .
Due to higher compression ratio peak pressure is higher so , heavier components (cylinder , piston , connecting rod , crank) are required in diesel engine Components are comparatively lighter in petrol engines.
Diesel Engine works on the Diesel Cycle Petrol Engines work on the Otto Cycle.
Diesel engines are practically more efficient because they work at higher compression ratios However , Otto Cycle is more efficient than Diesel Cycle for a given compression ratio but due to its low compression ratio it becomes practically less efficient .

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