Difference Between Two Stroke and Four Stroke

Q: Difference between 2stroke and 4stroke engine in operation aspects

4 stroke engine 2 stroke engine Low torque High torque Tough to manufacture and engines are costlier due to lubrication and valve. Simple to manufacture and engines are cheap More wear and tear happens because of poor lubrication Wear and tear are less Speed can be varied from high to low High speed engine are mostly available Operates in only one direction Operates in both direction (anti clockwise direction and clockwise direction)

Difference Between Two Stroke and Four Stroke - A Complete Guide

Edited By Team Careers360 | Updated on Sep 24, 2024 05:06 PM IST

In this article we will have a discussion about what is the difference between two stroke engine and four stroke engines, what is 2 stroke engine working principle, what is 4 stroke engine working principle.

4 stroke engine working

The 4 stroke engine is an integral part of the internal combustion engine. IC engines deliver outstanding performance with heavy durability which was used around years ago. IC engines use diesel, gasoline and also renewable energy such as natural gas as combustion fuel. Combustion is a chemical process of emitting energy from the fuel and mixture of air. It’s an internal combustion engine because the combustion of fuel and igniter happens internally i.e inside the engine. The engine has a piston which is a movable part and a cylinder which is fixed. This combustion gas will press the piston, which will rotate the crankshaft. With the gear system, this will drive the wheel’s vehicle.

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Difference Between Two Stroke and Four Stroke - A Complete Guide

4 stroke engine 1. intake - piston up 2. compressor 3. piston down 4. exhaust

Most of these IC engines are four stroke cycles. In four stroke cycle engines, to complete one cycle it needs four piston strokes. There will be two valves: intake valve and exhaust valve.
Also read -

The four piston strokes are

Intake
Compression
Ignition
Exhaust

4 stroke engine cycle comprises of 4process 1.intake 2.compression 3.ignition 4.exhaust

Intake

In this intake stroke, in the cylinder which is fixed part, the piston will moves from top position (TDC top dead center) to down position (BDC bottom dead center)
Intake value will be open
Exhaust value will be closed
The piston which moves downwards will create a vacuum that sucks the fuel and air inside the engine through the intake valve which is opened in this process.

Compression stroke:

In this compression stroke, the piston will now moves from down position (bottom dead center BDC) to top position (TDC top dead center)
Intake value will be closed
Exhaust value will be closed
The piston which moves upwards will compress the sucked fuel and air (in the intake process) inside the combustion chamber.
In this process, a spark of fire will be ignited.

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Power stroke:

The spark fire which happens in the compression stroke will ignite the air and fuel. This ignition will force the piston to move back downwards, making the vehicle wheel to rotate forward.
In this power stroke, the piston will now moves from top position (top dead center TDC) to bottom position (BDC bottom dead center)
Intake value will be closed
Exhaust value will be closed.

Exhaust stroke

In this exhaust stroke, the piston will now moves from down position (bottom dead center BDC) to top position (TDC top dead center)
Intake value will be closed
Exhaust value will be opened
This is the final process where the gas will be released through the exhaust valve of the cylinder. After completion of this process the piston is now ready for the intake process.

2 stroke engine

As the name suggests, the two stroke engine has only two stroke so only two piston movements.

Compression stroke
Power stroke

two stroke engine with inlet port and exhaust port

Compression stroke

In the compression stroke, the inlet port will be opened making the air and fuel mixture enter the compression chamber.
The piston will moves to top position
Here when the piston moves upwards, the mixture of fuel and air compression starts.
At the end of this process, a spark will ignite the fuel and begin the power stroke process.

Power stroke

In the power stroke, the fuel will be burnt and the gas will be exerted at high pressure causing the piston to move downwards.
The heat which is wasted will be emitted from the exhaust valve.

Two stroke engine and four stroke engine state the differences/difference between two stroke and four stock engine

Four stroke engine	Two stroke engine
In a four stroke engine to complete the four stroke process it requires two complete revolutions.	In a two stroke engine to complete the two stroke process it requires one complete revolution.
The four piston strokes are Intake Compression Ignition Exhaust	The two stroke are Compression stroke Power stroke
Inlet valve and exhaust valve	Inlet port and exhaust port
Consumption of fuel is full	Consumption of fuel is not full
High thermal efficiency and less smoke	Low thermal efficiency and high smoke
Exhaust gas removed easily	Exhaust gas removed is difficult
Engine weight is high for per hp because the flywheel is high	Engine weight is comparatively less for per hp
Low torque	High torque
Tough to manufacture and engines are costlier due to lubrication and valve.	Simple to manufacture and engines are cheap
More wear and tear happens because of poor lubrication	Wear and tear are less
Speed can be varied from high to low	High speed engine are mostly available
Operates in only one direction	Operates in both direction (anti clockwise direction and clockwise direction)

Application of two stroke and four stroke engine

Four stroke engine	Two stroke engine
Automobiles like cars, trucks and some bikes which uses fuel like gasoline, aircraft	Chainsaws, motorcycles, racing applications, weed eaters, military tanks, ships.
In four stroke engine are lubricated by oil so not flexible in cold temperature	In a two stroke oil sump is not in design hence it can be easily started in cold conditions.
High expensive and low noisy	Less expensive and more noisy

All the above mentioned points explain the difference between two stroke and four stroke engine/ difference between 2 stroke and 4 stroke engine/ 2 stroke vs 4 stroke.

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Frequently Asked Questions (FAQs)

1. Whether 3 stroke engine possible?

Practically there are four processes to perform such as intake, compression, ignition, and exhaustion. Leaving any one process we can’t operate an engine. Hence 3 stroke engine is not possible.

2. What functions happen in a four stroke engine?

In four stroke cycle engines, to complete one cycle it needs four piston strokes. There will be two valves: intake valve and exhaust valve.

The four piston strokes are

Intake
Compression
Ignition
Exhaust

3. Give an advantage of a two stroke engine over a four stroke engine?

In a two stroke engine for the same engine speed, it develops twice the number of power strokes compared to four stroke engine cycle. Compared to a four stroke engine for the same power developed, the two stroke engine is not bulky, lighter and floor area occupied is less.

4. Which is faster: 2 stroke engine or 4 stroke engine?

Stroke is the movement of a piston. A 2 stroke engine has two motions for the piston. Similarly 4 stroke engine has four motions for the piston. Hence two stroke engine will accelerate faster and unstable.

5. Difference between 2stroke and 4stroke engine in operation aspects

4 stroke engine	2 stroke engine
Low torque	High torque
Tough to manufacture and engines are costlier due to lubrication and valve.	Simple to manufacture and engines are cheap
More wear and tear happens because of poor lubrication	Wear and tear are less
Speed can be varied from high to low	High speed engine are mostly available
Operates in only one direction	Operates in both direction (anti clockwise direction and clockwise direction)