Whats the difference between a gasoline engine and a diesel engine?
The difference is much more simple than any of the other answers that have heretofore been posted. A gasoline engine uses a spark plug to ignite its fuel. A diesel engine, operating at a much higher compression ratio, uses the heat produced by compression to ignite its fuel. A diesel engine, therefore, does not have spark plugs, nor the related ignition system found in a gasoline engine. Other than this, diesel engines are very similar to gasoline engines, operating on the same principles, and existing in more or less the same variations. [Added 12 July 2005 11:20] David Hedrick’s comment that all diesels are two-stroke is completely wrong. Diesels exist in two and fourstroke versions, just as gasoline engine do, and most diesels used in vehicles just as with gasoline engines are fourstroke.
In a gasoline engine, a mixture of gasoline and air, controlled by a throttle, is inducted into a cylinder. Some engines use aftermarket cold air intakes to gain horsepower, torque, and throttle response. This is compressed by a piston and at optimal point in the compression stroke, a spark plug creates an electrical spark that ignites the fuel. The combustion of the fuel results in the generation of heat, and the hot gases that are in the cylinder are then at a higher pressure than the fuel-air mixture and so drive the piston back down. These combustion gases are vented and the fuel-air mixture reintroduced to run a second stroke. The outward linear motion of the piston is ordinarily harnessed by a crankshaft to produce circular motion. Valves control the intake of air-fuel mixture and allow exhaust gases to exit at the appropriate times. A critically important portion of any internal-combustion engine is its ignition system, which controls the timing of the burning of the fuel mixtur
Mechanically the two are very similar, sharing most significant design elements (block, crank, pistons, rings, oil bearings, heads, intake manifold, exhaust system… most large gas and diesel have valves and a cam shaft). Most automotive gas and diesel engines have a fuel pump and fuel injectors. Both can be designed as two-stroke or four-stroke. Some of the most significant differences: Diesels do not need an ignition system – no coil, distributor, or spark plugs – but instead depend on the heat of compression to burn fuel. Before the engine is hot, “glow plugs” can be used to start combustion, but they are not timed like spark, they just stay hot. Gas engines control power production with a throttle that reduces air pressure in the intake manifold so less air and fuel get into the cylinder. Diesels have no throttle (this gives them a small efficiency advantage), they control power by pumping less fuel into the cylinder. Gas engines add fuel to the air before it enters the cylinder,
I cannot give you a complete answer at this time, however I can tell you that Diesel fuel requires compression, and that it does not burn the way Gasoline does, rather it explodes when enough pressure is exerted on it (in the presence of a spark). In essence, the engines are completely different, although once you get past the combustion chambers and reach the crank shaft, the rest is very similar. Putting a small amount of gasoline into the diesel fuel will not terribly adversely affect the diesel engine. However, diesel in your gasoline can make your gas engine nearly inoperable.
