Check the difference 2 Stroke vs 4 Stroke Engine

Here I am going to tell you about what is main difference between 2 strokes vs 4 stroke engines. Before discussing on this topic let’s start with basic about stroke. The stroke in an engine is nothing but the distance covered by the piston from top dead center to the bottom dead center. In simple language, stroke is the distance of cylinder between piston moves. In 2 stroke engine piston moves 2 times in the cylinder and in 4 stroke engine piston moves 4 times in the cylinder. The crankshaft rotates one time between 2 strokes.


The basic and main difference between two stroke and four stroke engine is that

  • In 2 stroke engine one power stroke complete one crankshaft revolution and
  • In 4 stroke engine one power stroke complete two crankshaft revolution.

how two stroke engine work

2 stroke engine

4 Stroke engine

2 stroke engine produce high power compare to 4 stroke engine but the 4 stroke engine is more fuel efficient. There are many other differences which are given below.


S. No.


Two Stroke Engine

 Four Stroke Engine

1. one power stroke complete one crankshaft revolution one power strokes complete two revolution of crankshaft
2. It can generate high torque or power compare to 4 strokes engine. It generates less torque or power due to 2 revolution of crankshaft between one power strokes.
3. inlet and outlet of fuel done by port inlet and outlet of fuel done by valve
4. Require lighter flywheel because it generate more balance force due to one revolution of crankshaft. It requires heavy flywheel because it generates unbalance force due to two revolutions for one power stroke.
5. The charge in 2 stroke engine is half burn and mix with the burn gases during inlet. The charge in 4 stroke engine is fully burn and does not mix with the burn gases.
6. Lubrication is easy due to lubrication oil mix with the fuel. Lubrication is hard
7. Require More amount of lubricating oil  because some oil burns with fuel. Comparatively require less amount of  lubricating oil.
8. Less thermal efficiency High thermal efficiency
9. It has high power to weight ratio compare to 4 stroke It has less power to weight ratio.
10. It creates high  noise. It creates low  noise.
11. This type of engine are less efficient and generate more smoke. This type of engines are more efficient and generate less smoke.
12. Cheaper engine Expensive engine
13. easy to manufacture. hard to manufacture.
14. Lighter in weight Heavier in weight
15. These are mostly used in ships, scooters etc. These engines mostly used in car, truck, and other automobiles.
16. more wear and tear occurs Less wear and tear occurs.


Gopinath Murthi

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