Difference between Petrol and Diesel Engine

The petrol engine works on the otto cycle while the diesel engine works on the diesel cycle.

Here are some of the main differences between them to help you understand how both differ:

Petrol Vs Diesel Engine:


The Petrol engines are internal combustion engines.

They also have spark-ignition.

They operate on slightly volatile fuels like gasoline.

 Additionally, air and gasoline in petrol engines generally mix post-compression.

 Also, as previously noted, these engines run on the Otto cycle.

It consists of two isochoric and two isentropic activities.

With these engines, air and gasoline are often combined in a carburetor before being launched into the cylinder.


Diesel engine is internal combustion engines as compared to petrol.

A compression-ignition engine is another name for it.

The heated air in the combustion chamber ignites the fuel when it is fed into the chamber. Also, the air in their cylinders is quite hot. It is due to adiabatic compression.

 As a result, you can observe how diesel engines merely compress air and not fuel.

When diesel fuel is pumped into the combustion chamber, it will spontaneously ignite.

What is the Difference between Petrol and Diesel Engine?

What is the Difference between Petrol and Diesel Engine?

Diesel engines are another form of internal combustion engines, also known as a compression-ignition machines, whereas petrol engines are spark-ignition autos.

So, what’s the difference?  Let’s discuss the difference between t and how they are similar but not the same.

Petrol EngineDiesel Engine
This engine uses the Otto cycle.Most engines are using the Diesel cycle.
A carburettor combines air and gasoline.Inside the cylinder, gasoline, and air are combined.
An electric spark ignites the fuel.Ignition is accomplished with the assistance of hot, pressurized air.
The compression ratio is rather low.The compression ratio is high.
A gasoline engine generates relatively little power.High output power.
These internal combustion engines run on very volatile fuels.Diesel engine run on fuel with minimal volatility than petrol.
Used in small vehicles like motorbikes and automobiles.Usually found in big vehicles like trucks and buses.
Excessive fuel use.Fuel usage is rather low.
Initial and ongoing costs are quite inexpensive.High initial and ongoing expenditures.
Also read: Difference between Force and Pressure


The major difference between diesel and petrol engines is that spark plugs are used to ignite the air-fuel mixture in the petrol engine, whereas diesel engines rely exclusively on highly compressed air.

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