The vast majority of diesel engines in service today use solid injection and the information below relates to that system. In the diesel engine, only air is introduced into the combustion chamber.
The air is then compressed to about 600 pounds per square inch (psi), compared to about 200 psi in the gasoline engine. This high compression heats the air to about 1000 degrees Fahrenheit. At this moment, fuel is injected directly into the compressed air.
The fuel is ignited by the heat, causing a rapid expansion of gases that drive the piston downward, supplying power to the crankshaft. In Diesel's manuals, he described the supply of compressed gas into the cylinder to promote the final burn. It is now possible to fumigate the air intake with a small quantity of LPG/CNG.
The now air-gas mixture is compressed as above, and when the diesel ignites, the small quantity of gas ignites as well, causing a more rapid and more complete burn of the diesel. Most diesel engines waste between 30 and 15% of the diesel fuel, so by burning the near total amount of diesel consumed on each stroke, the mechanical effect is to improve the torque curve by as much as 28%.
The net outcome of applying gas into diesel is improved fuel economy via better torque at the driving wheels resulting in fewer gear changes, and greatly reduced exhaust emissions.
Advantages of the diesel engine are numerous. It burns considerably less fuel than a gasoline engine performing the same work. It has no ignition system to attend to. It can deliver much more of its rated horsepower on a continuous basis than can a gasoline engine. The life of a diesel engine is generally longer than a gasoline engine. Although diesel fuel will burn in open air, it will not explode unless compressed.
Some disadvantages to diesel engines are that they are very heavy for the horsepower they produce due to the required heavy design, and their initial cost is much higher than a comparable gasoline engine.
Recommended: Diesel Engine Repair Manuals
That was an excellent post - very informative - one thing though, a diesel is much noisier then a typical gasoline engine ;-)
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