4 stroke Engine Gif

Pic licence- File:4StrokeEngine Ortho 3D.gif by Zephyris under licence-CC BY SA 3.0

Stroke 1-Intake/Suction stroke-Petrol

In this stroke intake valve opens(valve on right side) and air and fuel mixture(Air mixed with petrol) comes in to the engine through Intake manifold(Blue coloured in animation) . At that time piston goes from TDC to BDC(Top to Bottom)and intake valve closes when piston reaches the BDC(Bottom dead centre).

Stroke 1-Intake/Suction stroke-Diesel

In Diesel engine only air comes in to the cylinder at the time of intake stroke, diesel will not be sucked inside at this time

Stroke 2- Compression stroke- Petrol

In this stroke piston moves from BDC to TDC and thus air fuel mixture is compressed inside the engine, so that the heat and pressure builds up inside the engine that makes the air fuel mixture highly inflammable.

Stroke 2- Compression stroke -Diesel

In Diesel engine only is air is being compressed inside the engine.

Stroke 3- Combustion/Power stroke- petrol

This stroke starts in the end of 2nd stroke , at the end of compression when piston reaches the top most position Spark plug gives a spark in the compressed air fuel mixture and in that force piston is pushed to the BDC in high pressure. In this stroke engine generates the power. Because of the power generated in this stroke piston moves 3 times again for all the other strokes.

Stroke 3-Combustion/Power Stroke-Diesel

In Diesel engine at the end of 2nd stroke (compression stroke) diesel is injected (IN high pressure-1000 bar) in to the hot compressed high pressure air and due the friction between air and diesel , diesel burns here.

Stroke 4- Exhaust stroke- Petrol/Diesel

In this stroke gases inside the engine after the burning of fuel is expelled out of the engine. While piston moves from BDC to TDC exhaust valve opens and burned gases are pushed out of the engine and then exhaust valve closes and the 1st stroke starts again. This process is same in both petrol and diesel engines.