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.
| 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. |
