Four Stroke Engine

Petrol Engine uses petrol as a fuel for combustion inside the cylinder. The petrol engine consist of a spark plug which ignite the air-fuel mixture (Air + Petrol). In petrol engine the carburetor prepare the require air fuel mixture Send it into the combustion chamber (Cylinder). Distance travelled between top dead centre and bottom dead centre is known as stroke.

Four Stroke Internal Combustion Engine

Four stroke internal combustion engine executes four complete strokes within the Cylinder while the crankshaft completes two revolutions for each thermodynamic Cycle.Petrol Engine uses petrol as a fuel for combustion inside the cylinder. The petrol engine consist of a spark plug which ignite the air-fuel mixture (Air + Petrol). In petrol engine the carburetor prepare the require air fuel mixture Send it into the combustion chamber  (Cylinder). Distance travelled between top dead centre and bottom dead centre is known as stroke.

Intake Stroke (Induction or Suction Stroke):

During the intake stroke, the piston moves downward, drawing a fresh charge of Vaporized fuel/air mixture.  The illustrated engine features a 'poppet' intake valve which is drawn open by the vacuum produced by the intake stroke.  Some early engines worked this way, however most modern engines incorporate an extra cam/lifter arrangement as seen on the exhaust valve.  The exhaust valve is held shut by a spring

Compression Stroke:

It is the process in which the fuel that was introduced into the engine cylinder is Compressed. During Compression Stroke the Piston moves from Bottom Dead Centre to Top Dead Centre. The Flywheel momentum drives the piston upward, compressing the fuel/air mixture. After the top dead centre the volume left is known as clearance volume. During Compression Stroke Both Intake Valve and Exhaust Valve remains closed.

Power Stroke (Combustion Stroke):

At the top of the compression stroke the spark plug fires, igniting the compressed fuel.  As

the fuel burns it expands, driving the piston downward. It is the only process in which the engine does work onto the surroundings.

Exhaust Stroke:

At the bottom of the power stroke, the exhaust valve is opened by the cam/lifter mechanism.  The upward stroke of the piston drives the exhausted fuel out of the Cylinder

Main PARTS of Four Stroke Petrol Engine

• Fly Wheel:Crank Shaft
• Connecting Rod
• Piston Rings
• Engine Chamber or Engine Cylinder
• Counter Weights
• Cooling Water Jackets
• Carburettor Inlet and Outlet Manifold Valve
• Tappets Rods
• Cam 
• Gears
• Spark Plug