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.

Two Stroke Engine




Four Stroke Engine


Difference between 2 stroke and four 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.  
Heavy flywheel is required and engine runs unbalanced because turning moment on the crankshaft is not even due to one power stroke for every two revolutions of the crankshaft.
Lighter flywheel is required and engine runs balanced because turning moment is more even due to one power stroke for each revolution of the crankshaft.
3.  
Engine is heavy
Engine is light
4. 
Engine design is complicated due to valve mechanism.
Engine design is simple due to absence of valve mechanism.
5. 
More cost.
Less cost than 4 stroke.

6.  
Less mechanical efficiency due to more friction on 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 gases exhaust.
Less output due to mixing of fresh charge with the hot burnt gases.
8.  
Engine runs cooler.
Engine runs hotter.
9.  
Engine is water cooled.
Engine is air cooled.
10. 
Less fuel consumption and complete burning of fuel.
More fuel consumption and fresh charge is mixed with exhaust gases.
11.  
Engine requires more space.
Engine requires less space.
12. 
Complicated lubricating system.
Simple lubricating system.
13. 
Less noise is created by engine.
More noise is created by engine.
14. 
Engine consists of inlet and exhaust valve.
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.



Image Source: https://imgur.com/gallery/eatFH

8 comments

Please tell me why four stroke engine has less wear and tear instead it has more frictional parts..??

Reply

Because they run at lower rpm.

Reply

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

Very useful information so thanks for this information

Reply

Well explained . Thank you

Reply

Thank you for this simple and important explanation

Reply

Could timing be more difficult to fix on a 4-stroke then a 2 stroke?

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