Difference between Petrol and Diesel Engine

The major difference between petrol and diesel engine can be attributed down into the structure, types and uses of these engines.However the main classification is done on the basis of types of fuel used. It is important to know the differences between these two as it can help engineering students or anybody interested to find out the key differences between the two types of engines. Engines usually run on the principle of heat transfer and it is important to know the principles to understand the mechanisms of engines.

Difference between Petrol and Diesel Engine

Apart from the type of fuel used, the engines are also divided on the basis of a lot of things, such as the presence of a spark plug in Petrol engines and a fuel injector in Diesel engines. We also know that lighter vehicles such as motorcycles, scooters and cars typically use petrol in their engines, whereas Diesel is used in much heavier machinery such as tractors, trucks and buses. Thus, the application of the types of fuel also plays a major role in defining the major difference between Petrol and Diesel. You can find more differences between the types of engines in the tabular column below:

Difference between Petrol and Diesel Engine

Petrol Engine

Diesel Engine

The engine works on the Otto cycle which also stands for the constant volume cycle.

This engine works on the Diesel cycle, the main principle stands for the constant pressure cycle.

No initial starting problem.

There is an initial problem in starting the engine.

A carburetor is usually present that takes the mixture of petrol and air, while igniting it with the spark plug.

In the diesel engine on the other hand, there is only a mixture of air, that ignites with the help of compression.

Petrol engines have a lower initial cost.

Diesel engines have a higher initial cost.

It is a much lighter engine compared to the Diesel engine.

Diesel engines are much heavier when compared to Petrol engines.

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