Difference Between 2-Stroke and 4-Stroke Engines

Most vehicles whether it is a car, motorcycle, bus, truck, etc. All have Internal combustion engines as a power source for their running. Now the engine used in them may be of two types whether it is a 2-stroke engine or a 4-stroke engine. Now a little bit of confusion appears in our mind about what is meant by 2 stroke and 4 stroke. So In this post, we will discuss in detail the difference between 2-stroke and 4-stroke engines. Let’s begin our discussion…

What are Two Stroke Engines?

In an internal combustion engine, when the piston moves from top to bottom or bottom to top, it is called one stroke. In a two stroke engine, the piston executes two strokes to produce power and so it is called a 2 stroke engine. The four process of suction, compression, power, and exhaust takes place in one complete revolution of the crankshaft.

Working of Two Stroke Engine?

What are Four Stroke Engines?

It is a type of internal combustion engine in which the piston moves 4 times up and down movement to produce power. In each movement or stroke, it executes 4 processes suction, compression, power, and exhaust. The 4 strokes of the engine are as follows

1. Suction Stroke: The suction of air-fuel mixture takes place in petrol engines and only air in diesel engines.

2. Compression Stroke: The compression of the air-fuel mixture in petrol engines and compression of air in diesel engines

3. Power stroke: The Combustion of air-fuel mixtures takes place by a spark plug in petrol engines and the combustion of diesel takes place by the heat of the air in diesel engines.

4 Exhaust Stroke: In this stroke, the burnt gases goes out of the engine cylinder and the piston move from BDC to TDC.

Working of Four Stroke Engine

Difference Between 2-Stroke and 4-Stroke Engines

S.No.Four-stroke engineTwo-stroke engine
1.It has one power stroke for every two revolutions of the crankshaft.It has one power stroke for each revolution of the crankshaft.
2.A heavy flywheel is required and the engine runs unbalanced because the turning moment on the crankshaft is not even due to one power stroke for every two revolutions of the crankshaft.A lighter flywheel is required and the engine runs balanced because the turning moment is more even due to one power stroke for each revolution of the crankshaft.
3.The engine is heavy in Weight.The engine is lighter in weight.
4.Engine design is complicated due to the valve mechanism.Engine design is simple due to the absence of valve mechanism.
5.It is costlier.Less cost than 4 stroke engine.
    6.Less mechanical efficiency due to more friction in many parts.More mechanical efficiency due to less friction on a few parts.
7.More output due to full fresh charge intake and full burnt gas exhaust.Less output due to mixing of fresh charge with the hot burnt gases.
8.The engine runs cooler. It means that engine runs on lower temperatures.The engine runs hotter. It means that the engine temperature is higher as compared with two-stroke engines.
9.The engine may be air-cooled or water-cooled.The engine is air-cooled.
10.Less fuel consumption and complete burning of fuel.More fuel consumption and a small amount of fresh charge are mixed with exhaust gases.
11.The engine requires more space.The engine requires less space.
12.Complicated lubricating system.Simple lubricating system.
13.Less noise is created by the engine.More noise is created by the engine.
14.The engine consists of an inlet and exhaust valve.The engine consists of inlet and exhaust ports.
15.More thermal efficiency.Less thermal efficiency.
16.It consumes less lubricating oil.It consumes more lubricating oil.
17.Less wear and tear of moving parts.More wear and tear of moving parts.
18.Used in cars, buses, trucks, etc.Used in mopeds, scooters, motorcycles etc.


This is all about the difference between 2-stroke and 4-stroke engines. I hope you have understood its major differences. If you found this piece of information useful and valuable then don’t forget to like and share it.

8 thoughts on “Difference Between 2-Stroke and 4-Stroke Engines”

Leave a Comment

Your email address will not be published. Required fields are marked *