Engine Ignition Spark Plug Function

A spark plug is a device used in internal combustion engines to ignite the fuel-air mixture. It generates an electrical spark at the correct time within the combustion chamber.

Petrol Engine Operation

Petrol engines, also known as gasoline engines or Spark Ignition (SI) engines, rely on a spark plug. The process involves:

• Compressing a mixture of fuel (petrol) and air in the cylinder.
• The spark plug then discharges a high-voltage current, creating a spark.
• This spark ignites the compressed fuel-air mixture, causing rapid expansion and powering the engine.

Other Engine Types

Other engine types function differently and do not use spark plugs for ignition:

• Diesel engines use compression ignition. High compression heats the air, and injected fuel ignites spontaneously without a spark.
• Steam engines use external combustion, where fuel is burned externally to heat water, producing steam to drive the engine. They do not have spark plugs for ignition within cylinders.

Therefore, the petrol engine is the type that uses a spark plug for igniting the fuel.