2 Stroke Vs 4 Stroke internal combustion engine

Introduction

The automobile we see in our daily life uses Air and fuel mixture to produce power through the combustion taking place inside the cylinder as discussed in previous topics. But there are 2 types of internal combustion process design ie 2 Stroke and 4 Stroke.

Now we need to understand the basics of how an engine works, what are these strokes, and how the combustion takes place, which we will discuss here.

The stroke is referred to as the displacement or movement of the piston from Top Dead Center ( TDC ) to Bottom Dead Center( BDC ) or vice versa.

Top Dead Center ( TDC ) is defined as the topmost position of a piston within the cylinder.

Bottom Dead Center ( BDC ) is defined as the lowermost position of the piston within the cylinder.

Now combustion is defined as the process of burning a substance in the presence of air ( oxygen ) to liberate heat and light.

Here fuel is burnt in the presence of air in a high pressurized area that produces power.

Now 2 stroke is defined as a process in which combustion of fuel in the presence of air takes place to produce power in 2 strokes only, On the other hand, if there take 4 strokes to produce power is called a 4 stroke engine.

There are 4 processes that take place ie

Suction Stroke- Suction of air and fuel mixture inside the cylinder ( gasoline engine ) and only air in the diesel engine.

Compression stroke- Compressing the air-fuel mixture in gasoline engines and air in diesel to a high range of pressure and temperature.

Power stroke- Burning of air and fuel mixture such that it produces power and pushes the piston to BDC that powers the crankshaft to the flywheel to the transmission system to differential to half shafts to the wheel.

Exhaust stroke- Pushing out of burnt gases from the cylinder through the exhaust valve to make the way for the fresh mixture to enter.

Thus, the above processed completes in 2 strokes are termed as 2 stroke engines, and if in 4 strokes are termed as 4 stroke engines.

There are pros and cons to both the type of engines, so it depends on what are your needs to decide which to opt for, but we will discuss in brief about them making your thoughts clear.

2- Stroke Engines

• It generates high torque
• Its uses ports for fuel’s outlet and inlet
• Engines are basically lighter and are noise
• Its engines result in lesser thermal efficiency
• It has a higher in terms of power to weight ratio
• It generates more smoke and shows less efficiency
• Engines are cheaper and are simple for manufacturing
• Two-stroke engines require pre-mixing of oil and fuel
• Requires more lubricating oil as some oil burns with the fuel
• For every power stroke it has 1 complete revolution of cranshaft
• A 2-stroke engine makes higher more at a higher RPM
• 2-stroke engine, burnt oil is also released along with the air.
• 2-stroke engines run at a higher RPM, hence they also tend to wear out faster
• Two-stroke engines are simpler in design, thus making them easier to fix. They do not have valves, but rather ports.

4-Stroke Engines

• It generates less torque
• Less wear and tear occurs
• Requires less lubricating oil
• The 4-stroke engine is also much quieter
• It uses valves for outlet and inlet of a fuel
• Its engines result in higher thermal efficiency
• It has a lesser in terms of power to weight ratio.
• Four-strokes are more environmentally friendly
• It generates less smoke and shows more efficiency
• For every power stroke, it has 2 crankshaft revolutions
• Engines are basically heavier because of the heavy flywheel and are less noisy
• Engines are comparatively expensive due to the lubrication and valves and are tough to manufacture.
• 4-stroke engines are heavier; they weigh 50% more than a comparable 2stroke engine.
• As far as efficiency goes, the four-stroke engines win. This is due to that fuel is consumed once in every 4 strokes.

2-stroke engines are typically found in smaller applications such as Scooters, remote control cars, and dirt bikes, etc. The best example to the 4-Stroke engine is the cars we see daily around us. So it’s up to you to decide which engine you prefer, and for what purpose.

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