Differences Between a 4-Stroke and a 2-Stroke Engine

The below table can be read like the table of comparison between the two types of engines and also as the merits and demerits of the two designs.

4-Stroke and a 2-Stroke Engine comparison

S.no	4-Stroke Engine	2-Stroke Engine
1	One working stroke for every 4 strokes or 2 revolutions.	One working stroke for every 2 strokes or one revolution.
2	As the number of cycles is less, power output is less for the same cylinder size.	Power is more for the same cylinder size. More suitable for diesel power plant.
3	The weight of the engine is more for the same output power.	The weight of the engine is considerably less. So, it is more suitable for marine engines.
4	The operating temperature is less. So, less consumption of lubricating oil.	The operating temperature is more. So, more consumption of lubricating oil. Special piston cooling is necessary for large engines.
5	Variation of torque is more. So, a heavier flywheel is necessary.	A smaller flywheel is enough as the torque is more uniform.
6	Noise is less.	Noise is more due to frequent exhaust.
7	Higher thermal efficiency.	Thermal efficiency is less due to possible wastage of fuel-air mixture through the exhaust port.
8	Due to the valve mechanism, the design and manufacture of the engines are difficult and the cost is more.	Easier in design and manufacturing cost is less.
9	The straight piston is used.	A deflector piston is used.