When gas is compressed, the temperature of it will rise,

with diesel engines using this very property to ignite

the fuel. Air is then drawn into the cylinder and

compressed by the rising piston at a much high

compression ratio than gas engines, up to 25:1, with

the air temperature reaching 700 – 900 degrees C.

At the top of the piston stroke, the diesel fuel is

injected into the combustion chamber at high pressure,

then through an atomizing nozzle, it mixes with the

hot high pressured air. The resulting mixture will

ignite and burn very rapidly. This combustion will

cause the gas in the chamber to heat up rapidly,

which increases the pressure and forces the piston


The connecting rod will transmit this motion to the

crankshaft. The scavenging of the engine is either

done by ports or valves. To get the most out of

a diesel engine, use of a turbocharger to compress

the intake of air is vital. You can also use an

aftercooler or intercooler to cool the intake air

after compression by the turbocharger to further

increase your efficiency.

An important part of older diesel engines was the

govenor, which limited the speed of the engine by

controlling the rate of fuel that was delivered.

Unlike gas engines, the air that comes in is not

throttled, so the engine would overspeed if this

wasn’t done. Older style injection systems were

driven by a gear system that came from the engine.

The diesel engine is truly an advancement to vehicles

as we know it. As technology gets better, you

can expect the diesel engine to get better as well,

possibly even proving just how much better it is

to the gasoline engine.

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