How Many Spark Plugs Does a Diesel Have? The answer is 0. The main feature of many automobile engines today is the principle of four-stroke combustion.
The principle of 4-stroke combustion in gasoline engines:
How Many Spark Plugs Does a Diesel Have?
- Intake stroke – The air and fuel mixture mixed in the carburetor is taken into the cylinder (combustion chamber).
- Compression time – This fuel and air mixture is compressed and ignited by the spark plug.
- Combustion time – The fuel burns and explodes, the pressure created pushing the piston down.
- Exhaust time – Burnt gases are expelled.
The principle of 4-stroke combustion in diesel engines:
- Intake Time: The piston goes down and only air fills into the cylinder.
- Compression Time: The piston moves upwards and compresses the air.
Air compression is much greater than in petrol engines so the air gets overheated. The temperature exceeds 800°C. Injectors inject diesel fuel here.
- Ignition and Burning Time: The ignition temperature of diesel is around 340 °C. The temperature inside is around 800 °C. Therefore, combustion takes place without the need for a spark plug.
At this stage, the work is produced. The piston is pushed down by the explosion effect as a result of combustion. During the explosion, the internal pressure rises up to 180 bar, depending on the engine type, and the temperature rises up to 2500 °C during combustion. This is the most efficient combustion. The spark plug cannot provide this efficiency. Because the calorific value of diesel is higher than gasoline engine. If a spark plug is used, it will cause only pre-ignition and a slight knock, as soon as the combustion is complete, the fuel is thrown away, so this is not preferred.
- Exhaust Time: Burning gases are thrown out.
As a result, diesel engines do not have spark plugs. Instead, there are fuel-injecting injectors. At the same time, as in gasoline engines, air and fuel mixing takes place inside the cylinder, so there is no need for a carburetor that mixes the two outside.