4 STROKE ENGINES
* 4 stroke engine completes 2 rotations of the crankshaft after completing one cycle.
* Power is produced once every 4 strokes of the piston.
* Engine design is a bit complicated due to valve mechanism which is operated through gear & chain mechanism.
* No need of adding oil or lubricant to fuel.
* Top side of the piston is flat.
* Mixture remains only in the combustion chamber.
* 4 stroke engines are heavier.
* 4 stroke engines make less noise.
2 STROKE ENGINES
* 2 stroke engine completes 1 rotation of crankshaft after completing one cycle.
* Power is produced once during 2 strokes of the piston.
* 2 stroke engine has ports which make its design simpler.
* Addition of oil is required.
* A bump or protuberance may be needed on the top side of the piston.
* Air-fuel mixture enters through inlet port & travels to combustion chamber passing through the crankcase.
* 2 stroke engines are lighter comparatively.
* 2 stroke engines are louder comparatively.
ADVANTAGE AND DISADVANTAGES
4 STROKE ENGINE:-
1. More torque:- In general, 4 stroke engines always make extra torque than 2 stroke engine at low RPM. Although 2 stroked ones give higher torque at higher RPM it has a lot to do with fuel efficiency.
2. More fuel efficiency:- 4 stroke engines have greater fuel efficiency than 2 stroke ones because fuel is consumed once every 4 strokes.
3. Less pollution:- As power is generated once every 4 strokes & also as no oil or lubricant is added to the fuel; 4 stroke engine produces less pollution.
4. More durability:- We all know that more the engine runs, quicker it wears out. 2 stroke engines are designed for high RPM. If an engine can go for 10000 rpm’s before it wears out; a 4 stroke engine with 100 rpm will run for 100 minutes than the other 2 stroke engine which has a higher rpm of 500 & will run for only 20 minutes.
5. No extra addition of oil:- Only the moving parts need lubrication intermediately. No extra oil or lubricant is added to fuel.
1. Complicated design:- A 4 stroke engine has complex valve mechanisms operated & controlled by gears & chain. Also, there are many parts to worry about which makes it harder to troubleshoot.
2. Less powerful:- As power gets delivered once every 2 rotations of the crankshaft(4 strokes), hence 4 stroke is less powerful.
3. Expensive:- A four-stroke engine has much more parts than 2 stroke engine. So they often require repairs which leads to greater expense.
2 STROKE ENGINE:-
1. Simple design & construction:- It doesn’t have valves. It simply has inlet & outlet ports which makes it simpler.
2. More powerful:- In 2 stroke engine, every alternate stroke is power stroke unlike 4 stroked one in which power gets delivered once every 4 strokes. This gives a significant power boost. Also, the acceleration will be higher & power delivery will be uniform due to the same reason.
3. The position doesn’t matter:- 2 stroke engine can work in any position as lubrication is done through the means of fuel (as the fuel passes by through whole cylinder & crankcase).
1. Less fuel efficiency:- For every alternate power stroke, fuel gets consumed every alternate stroke. This makes the engine less fuel efficient although it results in uniform power delivery.
2. Oil addition could be expensive:- Two-stroke engines require a mix of oil in with the air-fuel mixture to lubricate the crankshaft, connecting rod and cylinder walls. These oils may empty your pockets.
3. More pollution:- 2 stroke engine produces a lot of pollution. The combustion of oil added in the mixture creates a lot of smoke which leads to air pollution.
4. Wastage of fuel:- Sometimes the fresh charge which is going to undergo combustion gets out along with the exhaust gases. This leads to wastage of fuel & also power delivery of the engine gets affected.
5. Improper combustion:- The exhaust gases often get trapped inside the combustion chamber. This makes the fresh charge impure. Therefore maximum power doesn’t get delivered because of improper incomplete combustion.