The engine is one of the most important parts of the car. It is this part that drives the car. The engine can be either a petrol engine or a diesel engine. The working of both these engines is different. The basic difference is the presence of the spark plug. The spark plug is present in the petrol engine, but not in the diesel engine. The diesel engine uses compressed air to ignite the fuel, while the petrol engine uses the spark plug to ignite the fuel.
The diesel engine is more fuel efficient then the petrol engine. But till recent times diesel engines had a bad reputation. They were associated with huge cargo truck that makes loud clattering noise and gives out black smoke. This impression is slowly undergoing a change for the better. People have started using diesel engines in their cars and other vehicles.
The diesel engine like the petrol engine has four strokes.
Intake stroke is the stroke during which air is let into the cylinder. The intake of air forces the piston down. During this stage the exhaust valve remains closed.
Compression stroke is the stroke during which the air in the cylinder is compressed. This is done by the upward movement of the piston. Both the input and exhaust valves are closed during this stroke.
Once the air compressed enough, the fuel is injected into the cylinder. When is done the fuel ignites and forces the piston down. This stroke is called the combustion stroke. Both the input and exhaust valves remain closed during this stroke.
The ignited gas is then forced out of the cylinder through the exhaust valve by the piston. The intake valve remains closed. This stroke is called the exhaust stroke.
Marilyn has been working in the auto industry for many years. She has done a detailed study on Engine and Transmission World.