Difference between 4 stroke and 2 stroke engines

The following are the main differences between a four-stroke and two-stroke engines:

 

4-Stroke

2-Stroke

In a four-stroke engine all the four operations i.e. suction, compression, ignition, and exhaust are completed in two revolutions of the crankshaft. In two strokes engine, all four operations are completed in one revolution of the crankshaft.
Power is developed in every alternate revolution of the crankshaft. Power is developed in every revolution of the crankshaft.
The torque is less uniform; hence a four-stroke engine requires a heavier flywheel. The torque is more uniform than in the four-stroke engine hence a lighter flywheel is necessary for a two-stroke engine.
The suction and the exhaust are opened and closed by mechanical valves in a four-stroke engine In a two-stroke engine, the piston itself opens and closes the ports
In a four-stroke engine, the charge directly enters into the cylinder in a two-stroke engine

the charge first enters the crankcase and then flows into the cylinder

The crankcase of a four-stroke engine even though closed is not a pressure-tight chamber. The crankcase of a two-stroke engine is a closed pressure-tight chamber
In a four-stroke engine, the piston drives out the burnt gases during the exhaust stroke. whereas, in a two-stroke engine the high-pressure fresh charge scavenges out the burnt gases
The lubricating oil consumption in a four-stroke engine is less. The lubricating oil consumption in a two-stroke engine is more than in a four-stroke engine.
A four-stroke engine produces less noise. A two-stroke engine produces more noise than a four-stroke engine.
Since the fuel burns in every alternate revolution of the crankshaft in a two-stroke engine the rate of cooling are more than in a four-stroke engine. Since the fuel burns in every revolution of the crankshaft in a two-stroke engine the rate of cooling are more than in a four-stroke engine.
diesel engine 4 stroke A valveless two-stroke engines run in either direction

 

 

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