In this post, I am going to tell you about the difference between two stroke and four stroke engines. The main difference between them is that in 2 stroke engine the crankshaft revolves two times to complete its working cycle whereas in 4 stroke, the crankshaft does 2 revolutions to complete its working cycle.
Let’s try to understand their differences in detail.
Two Stroke Engine
Four Stroke Engine
Difference Between 2 Stroke and 4 Stroke Engines
| S.No. | Four stroke engine | Two 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 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 turning moment is more even due to one power stroke for each revolution of the crankshaft. |
| 3. | Engine is heavy in Weight. | 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 Temperature runs on lower temperatures. | 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 is 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. |
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Image Source: http://en.wikipedia.org/wiki/Four-stroke_engine
thanks for the info!
Please tell me why four stroke engine has less wear and tear instead it has more frictional parts..??
Because they run at lower rpm.
Bcoz in a 2 stroke engine, every second stroke is a power stroke… While in 4 stroke engine, power stroke comes after 4 strike movements..
Very useful information so thanks for this information
Well explained . Thank you
Thank you for this simple and important explanation
Could timing be more difficult to fix on a 4-stroke then a 2 stroke?