I was wondering the other day if all of the owners of the diesel engine powered vehicles rolling down the road had even a vague idea of how a diesel engine operates compared to a gasoline engine. And then I wondered how many folks understood how a gasoline engine worked..So I asked an individual who purchased a rebuilt engine from GotEngines.com this question..Their answer, No.
Let me make this brief. I will get to the root of how a diesel engine operates in theory. The basic premise or theory of operation stands true if you have an original 1892 Rudolph Diesel (inventor), diesel engine or a computerized turbo charged modern diesel.
The whole theory of operation is based on diesel oil as most oils, explode, without the help of spark plugs (as in a gasoline engine), when the compression or pressure in the cylinder reaches a predetermined amount of pressure in the cylinder. Based on this premise we can conclude that a diesel engine has a lot more compression than a gasoline engine. If there is no ignition device such as a spark plug to start the explosion process, then it is necessary to make enough pressure in the cylinder to explode the diesel oil.
FYI, O.K. then, this may not be fair to the laymen, and some mechanics too. But, have you ever noticed that on a set of welding torches that use oxygen and acetylene, that on the gauges it is clearly stated “Do Not Lubricate With Oil“? That is because the amount of pressure in the oxygen and acetylene tanks is so great, that one drop of oil can cause an explosion, which may cause the tanks to explode too. Simply put, this theory applies whenever oil and lots of pressure meet.
How much pressure is this? In the case of a diesel engine, we have anywhere from 17 to 1 compression ratio to 25 to 1 compression ratio. Which translates into pressures in excess of 300 to 500 (PSI) pounds per square inch in the cylinder. Where as, a gasoline engine ranges from approximately 8 to 1 compression ratio to 12 to 1 compression ratio. Which translates into cylinder pressures ranging from 150 PSI to 225 PSI in the cylinder..
Although gasoline is more refined and ignitable, it requires the assistance of spark plug to ignite the fuel. As opposed to the diesel engine, where the pressure itself causes the explosion.
In a nut shell, that is how your diesel engine works. As the compression lessens in a diesel engine, the performance drops and requires a rebuilt engine at this point. Another bit of interesting, yet perhaps trivial to many people by Got Engines.com blog.