The difference between a two-stroke and a four-stroke engine is crankshaft and piston speed. In this article, we will learn more about the difference between two strokes and four strokes.
What Is a Two-Stroke Engine?
A two-stroke engine is an engine that completes the power cycle by firing two pistons during only one revolution of the crankshaft.
After one cycle the engine can generate power due to the simultaneous intake of air inside the cylinder and exhaust of residual gases.
There is an intake shock valve that opens and closes for different weights. However, due to greater friction with moving parts, fuel is mixed with oil for increased lubrication, allowing a frictionless effect.
What Is a Four-Stroke Engine?
A four-stroke engine is an internal combustion engine in which the piston completes four different strokes while turning the crankshaft.
The four-stroke engine has four successive stages from intake, compression, power to exhaust. Each is equal to one full stroke of the piston.
So each of the pistons provides one power stroke for two revolutions (or four piston strokes) and two rotations of the crankshaft are required for the entire cycle.
Difference between Two Stroke and Four Stroke
| Two Strokes | Four Strokes |
| It has one revolution of the crankshaft during one power stroke. | It has two revolutions of the crankshaft during one power stroke. |
| It generates high torque. | It generates less torque. |
| It uses a port for the fuel’s outlet and inlet. | It uses valves for the fuel’s outlet and inlet. |
| Its engines result in lesser thermal efficiency. | Its engines result in higher thermal efficiency. |
| It has a larger ratio in terms of power to weight. | It has a lesser ratio in terms of power to weight. |
| It generates more smoke and shows less efficiency. | It generates less smoke and shows more efficiency. |
| Requires more lubricating oil as some oil burns with the fuel. | Requires less lubricating oil. |
| Due to poor lubrication, more wear and tear occurs. | Less wear and tear occurs. |
| Engines are cheaper and are simple to manufacture. | Engines are expensive due to lubrication and valves and are tough to manufacture. |
| Engines are basically lighter and noisier. | Engines are basically heavier because their flywheel is heavy and less noisy. |
