Difference Between 2 Stroke and 4 Stroke (With Table)

A variety of engines are available for automobiles, each with its unique characteristics. 2 stroke and four-stroke engines, on the other hand, are the two most common types of engines.

To generate mechanical energy, the piston travels a predetermined distance from the top dead centre (TDC) to the bottom dead centre (BDC). Engines perform a stroke as their primary purpose, which initiates the combustion process inside the machine.

2 Stroke vs 4 Stroke

The main difference between Two-stroke and four-stroke engines is fundamentally different in how they are driven. On the other hand, flywheels are required for 4-stroke engines, although flywheels for 2-stroke engines are less critical. Additionally, the two engines can be distinguished based on their use, with two-stroke engines being most commonly found in scooters and mopeds. In contrast, four-stroke engines are more widely seen in heavier trucks or off-road vehicles.

In a two-stroke engine, the entire combustion cycle ends with one piston stroke: the compression stroke, followed by the compressed gasoline’s detonation. A new fuel mixture is introduced into the cylinder as the exhaust is expelled during the return stroke.

Each rotation of a 4-stroke engine involves the piston making two full strokes: one compression and one exhaust, followed by a return. Power is generated every four strokes in a piston engine, yet the spark plugs only ignite once every other rotation.

Comparison Table Between 2 Stroke and 4 Stroke (in Tabular Form)

Parameter of comparison2 Stroke4 Stroke
No. of crankshaft revolutionThe crankshaft completes one revolution during a single power stroke on the engine.During a single power stroke, the crankshaft makes two complete rotations.
Fuel’s Outlet and InletIt makes use of a port for the input and exit of fuel.It uses valves to regulate the flow of gasoline into and out of the engine.
Thermal EfficiencyBecause of its engines, it has lower thermal efficiency.Because of its engines, it achieves superior thermal efficiency.
CostEngines are less expensive and easier to manufacture than other types of machinery.In addition to being costly owing to lubrication and valves, engines are also challenging to produce.
Smoke GenerationIt produces more smoke and performs less efficiently than the previous model.It emits less smoke and performs more efficiently than previous models.
Noise ProductionEngines are often smaller, lighter, and noisier.Engines are often heavier due to the weight of the flywheel, and they are also less loud.

What is 2 Stroke?

Two-stroke engines are most commonly seen in scooters and mopeds, but they are also found in small engine tools and some types of trimmers these days, among other things. The name itself shows how it operates; to generate power, the engine must complete only two strokes, namely the compression stroke and the combustion stroke, and as a result, these engines are referred to as two-stroke engines.

Every time the piston turns, the spark plugs light, and power is generated once every two piston strokes. There are five steps in the combustion process for two-stroke engines: induction, compression, ignition, combustion, and exhaust. The whole process is finished after two piston strokes, which is the length of the engine’s stroke.

In contrast to other four-stroke engines, two-stroke engines burn the fuel mixture with each piston spin, making them faster than four-stroke engines. Two-stroke engines do not have valves and fire with each piston revolution.

Two-stroke engines feature fewer moving components, making them more affordable and straightforward to maintain. As a result, it takes up less physical space. A high power-to-weight ratio is the foundation of their design. Because there is no need to care about the oil flow from any valves, two-stroke engines can be placed in any direction without causing damage.

Two-stroke engines are used in a variety of applications, including:

  1. Lawn and garden equipment, bicycles, and jet skis are recreational vehicles.
  2. Small outboard motors are available.
  3. Models that can be controlled via radio

What is 4 Stroke?

An internal combustion engine with four strokes is also known as a four-stroke engine. In contrast to two-stroke engines, which use ports to extract fuel and air from the surrounding environment, four-stroke engines use intake and exhaust valves. 4 stroke engines have four sequential strokes: suction, compression, power, and exhaust. These are the four strokes that take place in a single-engine.

Four-stroke engines take four strokes to complete one cycle of operation. The crankcase is a vital component of the machine since it is responsible for keeping the engine isolated from the combustion chamber so that combustion may take place correctly. Consequently, you only need to lubricate the gears and other bearings of the machine by adding oil to the oil reservoir when the engine is running.

After completing the intakes stroke, the piston moves upwards again to reach the cylinder and close the intake valve. Just before the piston reaches the top dead center, the spark plug emits a spark to ignite the gasoline mixture, which causes the engine to start.

An engine compression stroke is initiated and completed at this point. Because of the ignition, the piston is pushed down into the cylinder. (See illustration.) The power stroke is responsible for the engine’s ability to produce power.

The exhaust valve opens when the piston is pushed down, escaping the exhaust. As soon as the valves are opened, the piston is propelled upwards until it reaches the cylinder; once it has caught the cylinder, the exhaust gases are expelled through the exhaust port provided in the engine design.

Main Differences Between 2 Stroke and 4 Stroke

  1. One of the most significant differences between two- and four-stroke engines is how they operate, i.e., how the crankshaft and piston move about each other.
  2. It is also essential to compare their performance, maintenance costs, and efficiency to see the differences between them and their applications.
  3. The power output of four-stroke engines is high, and they are less loud. When compared to two-stroke engines, it has lower maintenance costs.
  4. Both engines have diverse applications, which is another distinction. The two-stroke engine is utilized in small and light equipment, whereas the four-stroke engine is employed in heavy-duty equipment and machines that dump materials.
  5. Unlike two-stroke engines, which are tiny and take up less room, four-stroke machines take up a significant area and are difficult to manage. Two-stroke engines are simple to handle.

Conclusion

It is vital to have both two-stroke and four-stroke engines to perform various tasks. On the other hand, four-stroke engines are more efficient and require less maintenance than two-stroke engines.

As opposed to four-stroke engines, which are more expensive, take up more room, and require more skill and training to run, two-stroke engines are simpler to operate. As a result, both machines have their advantages and disadvantages.

References

  1. https://www.jstor.org/stable/44724377
  2. https://www.jstor.org/stable/44742810