If you drive a gasoline-powered vehicle, spark plugs are used to start the engine and move the vehicle.
Does diesel engine have spark plugs
These small components deliver an arc of electrical charge that ignites the fuel and air mixed in the cylinder head. The resulting explosion sets the piston in motion in the cylinder. The moving piston then moves the crankshaft, and this motion is transferred to the transmission and then to the drive shaft, causing the vehicle to move.
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| does diesel engine have spark plugs |
A diesel engine vehicle starts in much the same way. The only difference is that it doesn't need a spark plug to get things started.
Why is that? Well, it all has to do with compression.
First, a little physics. Air heats up when it's compressed. Squeeze it into an engine cylinder fast enough and the temperature and environment will be just right for it to ignite the fuel without needing a spark. This is what happens in a diesel engine. Air is compressed, diesel fuel is injected into the ignition chamber and instantaneous combustion occurs.
Incidentally, compression is also part of the reason why diesels are so much more fuel efficient (up to 30% more) than gasoline vehicles. All vehicles - gasoline or diesel - have a defined compression ratio. This ratio is the volume (or capacity) of an engine cylinder when the piston is at the bottom of the cylinder compared to the volume of the combustion chamber (the bit at the top of the cylinder where the fuel/air mixture is ignited) when the piston is at its highest reach in the cylinder. In a gasoline car, this ratio will be between 8:1 and 10:1. In a diesel, it can be anywhere from about 16:1 to over 20:1. The higher the ratio, the more air is compressed and the more fuel is ignited during combustion. The result is a more powerful explosion and better performance.
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While compression ignition means that diesels do not need spark plugs, they can be equipped with components called glow plugs.
Although glow plugs do not ignite the fuel, they are useful when an engine or the environment in which the vehicle is located is very cold. They are essentially small heaters that warm the compressed air in the cylinder, helping to heat up the compression and aid in ignition when a cold engine is first started.