How Does a Car Engine Work?

Combustion

The combustion process is what gives a car engine its power. It’s the process of burning fuel to create heat, which is then used to turn the engine’s crankshaft. The crankshaft is connected to the wheels, so the heat from combustion is what ultimately makes the car move.

The Four Strokes of Combustion

The combustion process in a car engine happens in four strokes:

• Intake stroke: The intake valve opens and the piston moves down, drawing air and fuel into the cylinder.
• Compression stroke: The intake valve closes and the piston moves up, compressing the air and fuel mixture.
• Power stroke: The spark plug ignites the air and fuel mixture, causing it to burn and expand. This expansion forces the piston down, turning the crankshaft.
• Exhaust stroke: The exhaust valve opens and the piston moves up, pushing the exhaust gases out of the cylinder.

Factors Affecting Combustion

Several factors can affect the combustion process in a car engine, including:

• Air-fuel ratio: The air-fuel ratio is the ratio of air to fuel in the air and fuel mixture. A rich mixture contains more fuel than air, while a lean mixture contains less fuel than air. The ideal air-fuel ratio for most gasoline engines is 14.7:1.
• Spark timing: The spark timing is the point at which the spark plug ignites the air and fuel mixture. The spark timing must be precise to ensure that the mixture ignites at the optimum time.
• Compression ratio: The compression ratio is the ratio of the volume of the cylinder when the piston is at the bottom of its stroke to the volume of the cylinder when the piston is at the top of its stroke. A higher compression ratio results in more power, but it can also lead to knocking.
• Engine speed: The engine speed is the number of revolutions per minute (rpm) at which the engine is running. The engine speed affects the combustion process by changing the amount of time available for the air and fuel to mix and burn.

Conclusion

The combustion process is a complex one, but it’s essential for understanding how a car engine works. By understanding the factors that affect combustion, you can help ensure that your engine is running at its best.