For Stroke Petrol Engine

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A four-stroke engine, also known as a four-cycle engine, comprises four separate strokes that constitute a single thermodynamic cycle. A stroke denotes the piston's complete travel along the cylinder in either direction. The four distinct strokes are named intake, compression, power, and exhaust. During the intake stroke, the piston descends from top dead center to increase the cylinder volume, allowing a fuel-air mixture to be forced into the cylinder via atmospheric or air pump pressure. The compression stroke follows with both valves closed as the piston returns to top dead center, compressing the air-fuel mixture. In the power stroke, close to Top Dead Centre, the compressed air-fuel mixture is ignited in a gasoline engine by a spark plug or in a diesel engine due to compression heat, driving the piston down towards bottom dead centre. Lastly, the exhaust stroke sees the piston return to top dead center with the exhaust valve open, expelling spent fuel-air mixtures through the exhaust valve(s).