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What Is 2-Stroke and 4-Stroke Engine?

by Er. Vatsal Bhatt

Hello everyone, We discuss about automobile engine in previous article. Now we will discuss about 2-stroke and 4-stroke engine in detail. Generally 2-stroke and 4-stroke both engine performs suction , compression , power and exhaust strokes. Now lets discuss about this strokes in 2-stroke engine.

Also Read:- What is automobile engine?

2-stroke engine :

Suction stroke :- This is the initial stage of engine. when we start the engine and mesh the gears suction stroke is performed by engine. in suction stroke piston moves T.D.C (top dead center) to B.D.C (bottom dead center). in this position fuel  enters in combustion chamber.it is the small chamber where fuel burns.after this moment crank shaft rotates 0 to 90 degree.  in this stroke  inlet port remains open and outlet port becomes close. this process done by piston surface only.after this process compression stroke begins.

Also Read:- What is Automobile Clutch?

Compression stroke :- In this stroke piston moves B.D.C to T.D.C and fuel is compressed by piston top surface.in this stroke crank shaft rotates 90 to 180 degree.in this stroke inlet and outlet both port remains close.actually in 2-stroke engine suction and compression both stroke performs together..

Power stroke:- In this stroke piston moves T.D.C to B.D.C again.and crank shaft rotates 180 to 270 degree.in this stroke inlet and outlet both port remains close. in this stroke spark plug gives the spark to fuel and fuel burns. so this is the most important stroke of engine. due to this stroke engine starts.

Exhaust stroke :-  In this stroke piston moves b.d.c to t.d.c and crank shaft rotats 270 to 360  degree.in this stroke inlet port becomes close and outlet port  remains open by piston side surface. in this stroke burnt fuel comes outside by outlet port in form of white smoke.actually in 2-stroke engine power and exhaust both strokes performs together.

2 – stroke engines were used in two wheeler and mopeds. but now a days in all vehicles we use 4 – stroke engine. now lets understand about 4 – stroke engine.
2-stroke 1
2-stroke 2
2stroke 3

4 – Stroke engine :

As i say 2 stroke and 4 stroke both engine performs same strokes. now lets understand suction , compression , power and exhaust stroke in 4- stroke engine.

Suction stroke :- In this stroke piston moves T.D.C to B.D.C and crank shaft rotates 0 to 90 degree. in this stroke inlet valve remains open and outlet valve becomes close. in 4- stroke engine valves are used instead of  port.in this stroke fuel enters in to the combustion chamber via inlet manifold. this is the initial stage of 4- stroke engine. in this stroke fuel is sucked so its called suction stroke.

Compression stroke :- In this stroke piston moves B.D.C to T.D.C and crank shaft rotets 90 to 180 degree.in this stroke inlet and outlet both valve remains close. in this stroke fuel is compressed by piston top surface. in 4 – stroke engine all the strokes  are performed individually.

Power stroke :- In this stroke piston moves T.D.C to B.D.C and crank shaft rotets 180 to 270 degree. in this stroke inlet and outlet both valve remains close. in this stroke spark plug gives spark to burn the fuel. this is the most important stroke of engine because due to this process engine gets start.

Exhaust stroke :- In this stroke piston move B.D.C to T.D.C and crank shaft rotets 270 to 360  degree.in this stroke inlet valve becomes close and outlet valve remains open. in this stroke burnt fuel comes outside via outlet valve in form of white or black smoke.therefore this stroke calles exhaust stroke.
4stroke 2
4 stroke 2
4 strokes of engine 1

Now we are knowledgeable about 2 stroke and 4 stroke engine. as we knew that in both engine all the processes are same but there is minor difference  between two stroke and four stroke engine as shown below.

in 2 stroke engine we use port for passing the fuel and in 4 stroke engine we use valves for passing the fuel.

2 stroke engine made in single cylinder it has no firing order  while 4 stroke engine are made in multi – cylinder so it has a firing order as per cylinder used.for ex. 6 – cylinder engine’s firing order is 1-5-3-6-2-4.

2- stroke engine is less efficient and more fuel consumptive while 4-stroke engine is more efficient and less fuel consumptive.

2 – stroke engines uses in mopeds and 2 wheelers only while 4 stroke engines are used in cars and other commercial vehicles.