Difference Between Four-stroke and Two-stroke Engine [With PDF]

Amrit Kumar
Reading Time: 3 minutes

Hey, how are you? Assuming you are good! Today our discussion on Four-Stroke vs Two-Stroke Engine.

As we all know the there are two types of engines (although there are various kinds of engines are available however these are some popular engines we are talking about) one is four-stroke another one is two-stroke. OH! also there is another type of engine, Dual Combustion Engine, however, today we will differentiate between these two engines (2-Stroke & 4-Stroke), so let's dive into the topic.

First, let's see what is a Two-Stroke Engine?

We call an engine 2-stroke when the four successive strokes, i.e. Suction, Compression, Power, and Exhaust are completed in 1 revolution of the crankshaft, which means in the 360-degree rotation of a crankshaft all the successive strokes are completed.

And What is a Four-Stroke Engine?

And again we call an engine 4-stroke when the same successive strokes (Suction, Compression, Power, and Exhaust) are completed in the 2-revolution of the crankshaft. i.e. 720-degree rotation of the crankshaft.

These are the basic things you know when you find the differences, so now let's see some more differences between a 4-stroke engine and a 2-stroke engine.

RECOMMENDATION: We already have an in-depth article on the Four-Stroke Engine and how it works? and Also on Two-Stroke Engine. I will suggest you to reading those articles too.

Difference Between Four-stroke and Two-stroke Engine:

2-stroke vs 4-stroke engine
FOUR-STROKE ENGINE TWO-STROKE ENGINE
In this type of engine, power is developed in every two revolutions of the crankshaft.In this type of engine, power is developed in every revolution of the crankshaft.
Torque is not more uniform in a 4-stroke engine.Torque is more uniform in a 2-stroke engine.
The 4-stroke engine requires heavy flywheel.The 2-stroke engine requires lighter flywheel.
In this type of engine, we see the presence of an inlet and exhaust valve. And valve acting mechanism for opening and closing for intake or outlet of charges and burned gases respectivelywhereas in the 2-stroke engine has Inlet and exhaust ports are present.
Charges (Air and fuel mixtures) or only Air directly enter into the cylinder.Charges (Air and fuel mixtures) first enter into the crankcase then enter s into the cylinder.
As in the 4-stroke engine, we get 1 power stroke in two revolutions of therefore we need less lubricant and coolant.As in 2-stroke engine power produce in each revolution we need greater cooling and lubricating arrangement to avoid wear, tear, and choking.
No scavenging process.
No scavenging process.The scavenging process takes place.
Produces  Less Noise.Produces More Noise.
Power output is more. Power output is less.
The maintenance cost is more. The maintenance cost is less.
More space is required. Required less space.
Engine starting is not easy. Engine starting is easy.
This type of engine is robust in construction. This is simple in construction.
Thermal efficiency is more. Thermal efficiency is less.
As we saw its weight is higher and there is a comparatively tough mechanism to operate this engine, therefore the initial cost of this engine is more.As of simple in design and less acting mechanism, the price point or the initial cost of this type of engine is comparatively lower than the four-stroke engine.
In a 4-stroke engine, we see higher volumetric efficiency because the intake capacity of the engine is more.In the case of the 2-stroke engine, the volumetric efficiency is quite lower because less amount of charge gets into the engine cylinder.

So these are the quite few difference between the 2-stroke engine and 4-stroke engine, let me know in the comment section if you know more differences between these engines, I will love to show more.

And yeah, if you have any doubts regarding this topic, feel free to comment down below, I will reply here.

FAQ:

What is a 2-Stroke Engine?

We call an engine 2-stroke when the four successive strokes, i.e. Suction, Compression, Power, and Exhaust are completed in 1 revolution of the crankshaft.

What is a 4-Stroke Engine?

we call an engine 4-stroke when the same successive strokes (Suction, Compression, Power, and Exhaust) are completed in the 2-revolution of the crankshaft.


References:

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