Difference Between 2 Stroke and 4 Stroke Engines

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

two Stroke engine

Image Source

Four 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.

Also Read:

  1.  What is CVT – Continuously Variable Transmission and How it Works?
  2. How DTSi Engine Works – Explained?
  3. What is ABS (Anti-lock Braking System) and How it Works?
  4.  How Torque Converter Works?
  5. Types of Superharger in Automobile

Image Source: http://en.wikipedia.org/wiki/Four-stroke_engine

Pankaj Mishra

Pankaj Mishra is a blogger by passion and Mechanical Engineer by profession. He has completed his B.Tech degree in mechanical engineering in the year 2015. He loves to share his knowledge and help others.

9 thoughts on “Difference Between 2 Stroke and 4 Stroke Engines

  • September 24, 2016 at 12:49 am
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    Please tell me why four stroke engine has less wear and tear instead it has more frictional parts..??

    Reply
  • February 6, 2017 at 8:41 pm
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    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..

    Reply
  • February 8, 2017 at 2:55 am
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    Very useful information so thanks for this information

    Reply
  • January 18, 2020 at 1:54 pm
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    Today, I went to the beachfront with my kids. I found a sea shell and gave it to my 4 year old daughter and said “You can hear the ocean if you put this to your ear.” She put the shell to her ear and screamed. There was a hermit crab inside and it pinched her ear. She never wants to go back! LoL I know this is completely off topic but I had to tell someone!

    Reply

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