Deisel engine



How is diesel fuel different from regular gas? What is the difference between a diesel engine and a regular engine?

Thank you,



Wow, that’s a pretty big question. This is a basic description of a diesel engine:

This is a basic description of a gasoline engine:

The two fuels are quite different, with different energy content, combustion characteristics, etc. Each type of fuel is optimized for the corresponding engine type.


Gas is a lighter fuel and as such has a lower flash point. Diesel is less refined and theoretically cheaper to produce. As to the differences between the engines, Diesel engines have a higher compression ratio and are always injected. Diesel engines rely on this high compression to ignite the fuel. Once a diesel engine is started, the only way to shut it down is to remove the fuel supply or remove the air supply. There is no ignition system. A gasoline engine can be either carburated or injected. Gas engines rely on a small electric spark to ignite the fuel. They must have air, fuel and spark to run. this is a very simplified answer, but covers the major points.


The gas engine has fuel introduced into the cylinder and the spark plug “sparks” and ignites the fuel causing the explosion of gas to force the piston down and rotate the crank.

The diesel engine has fuel introduced into the cylinder and when the piston comes up on the compression stroke the air/fuel mixture is compressed so much that the heat from this compression causes the explosion that in turn forces the piston down on the power stroke… that turns the crank…blah…blah …blah. My says I always give her to many car related details. Hope this helps.

All automotive engines are of the 4 stroke type. intake/compression/power/exhaust.


There are 2 stroke diesels and 2 stroke gas engines. 2 stroke diesels are used in trucks/buses ect.



how much diesel did you put into your gas tank??


Oil is composed of a mix of different hydrocarbons. Hydrocarbons are molecules with only carbon and hydrogen atoms. In includes natural gas, butane, octane cetane and even tar. Mixes of hydrocarbons become gasoline diesel, and the oil that goes in your car as well as a number of other products.

Gasoline is made of of a mix of the smaller hydrocarbons like octane (C8H18). Octane has 8 carbon atoms. diesel has a mix of heavier molecules like cetane (C16H34). Gasoline will evaporate faster and ignite faster. Don’t try it as it will not always work, but you can usually put a match out in diesel. Diesel has a little more energy per gallon than gasoline.

In the car a spark is used to ignite the gasoline and in the diesel compression is used. Diesels have far more compression than gasoline engines. Note: there are some variations on this.

Oil as it comes out of the ground contains both products. When refining it they start by distilling it to separate the different products. When we consumers want more of one other the other product than comes naturally out of the oil (not all oil is the same it varies in the mix) then they reform the mix, which increases the cost.