4-STROKE VS 2-STROKE ENGINES
4-STROKE ENGINES
- The 4-stroke engine completes 2 crankshaft rotations after completing one cycle.
- Power is produced once every 4 piston strokes.
- The design of the engine is a little complicated due to the valve mechanism which is operated through gear and chain mechanism.
- There is no need to add oil or lubricant to the fuel.
- The top of the piston is flat.
- The mixture only remains in the combustion chamber.
- 4-stroke engines are heavier.
- 4-stroke engines make less noise.
2-STROKE ENGINES
- The 2-stroke engine completes 1 crankshaft rotation after completing one cycle.
- Power is produced once during 2 piston strokes.
- The 2-stroke engine has ports, which makes its design simpler.
- Oil addition is required.
- A protuberance or bulge may be required on the top of the piston.
- The air-fuel mixture enters through the intake port and travels to the combustion chamber through the crankcase.
- 2-stroke engines are comparatively lighter.
- 2-stroke engines are noisier comparatively.
caption-attachment-9988″ > 
two stroke engine vs four stroke engine
ADVANTAGE AND DISADVANTAGES
4-STROKE ENGINE: –
BENEFITS
1. More torque: – In general, 4-stroke engines always produce extra torque than 2-stroke engines at low speeds. Although 2-strokes provide greater torque at higher RPM, this has a lot to do with fuel efficiency.
2. More fuel efficiency: – 4 stroke engines are more fuel efficient than 2 stroke engines because fuel is consumed once in every 4 stroke.
3. Less pollution: – As energy is generated once every 4 strokes and also because no oil or lubricant is added to the fuel; 4-stroke engine produces less pollution
4. More durability: – We all know that the more the engine works, the faster it wears out. 2-stroke engines are designed for high rpm. If an engine can reach 10,000 rpm before it wears out; a 4 stroke engine with 100 rpm will run for 100 minutes than the other 2 stroke engine which has higher rpm of 500 will run for only 20 minutes.
5. No extra oil addition: – Only the moving parts require intermediate lubrication. No extra oil or lubricant is added to the fuel.
DISADVANTAGES
1. Complicated design: – A 4-stroke engine has complex valve mechanisms operated and controlled by gears and chain. Plus, there are a lot of parts to worry about, which makes troubleshooting more difficult.
2. Less powerful:- As power is supplied once every 2 revolutions of the crankshaft (4 stroke), 4 stroke is less powerful.
3. Expensive: – A four-stroke engine has many more parts than a 2-stroke engine. Therefore, they often require repairs, which leads to greater expenses.
2-STROKE ENGINE: –
BENEFITS
1. Simple design and construction: – No valves. It simply has input and output ports, which makes it simpler.
2. More powerful: – In 2-stroke engine, each reciprocating stroke is a stroke of power, unlike in 4-stroke engine where power is supplied once in every 4 strokes. This provides a significant increase in power. Furthermore, acceleration will be greater and power delivery will be uniform for the same reason.
3. The position does not matter: – The 2-stroke engine can work in any position, as lubrication is done through the fuel (since the fuel passes through the entire cylinder and crankcase).
DISADVANTAGES
1. Less Fuel Efficiency: – For every alternate power stroke, fuel is consumed in every alternate stroke. This makes the engine less fuel efficient, although it results in even power delivery.
2. Adding oil can be expensive: – Two-stroke engines require a mixture of oil and air-fuel mixture to lubricate the crankshaft, connecting rod and cylinder walls. These oils can empty your pockets.
3. More pollution: – The 2-stroke engine produces a lot of pollution. The combustion of the oil added to the mixture generates a lot of smoke which leads to air pollution.
4. Waste of fuel: – Sometimes, the new charge that will be combusted comes out along with the exhaust gases. This leads to wastage of fuel as well as engine power supply.
5. Improper combustion: – Exhaust gases are often trapped inside the combustion chamber. This makes the new charge impure. Therefore, maximum power is not provided due to inadequate incomplete combustion.
