Diesel Engine

a"The basic difference between a diesel engine and a gasoline engine is that in a diesel engine, the fuel is sprayed into the combustion chambers through fuel injector nozzles just when the air in each chamber has been placed under such great pressure that it’s hot enough to ignite the fuel spontaneously.You turn the key in the ignition. Then you wait until the engine builds up enough heat in the cylinders for satisfactory starting. (Most vehicles have a little light that says “Wait,” but a sultry computer voice may do the same job on some vehicles.) Turning the key begins a process in which fuel is injected into the cylinders under such high pressure that it heats the air in the cylinders all by itself. The time it takes to warm things up has been dramatically reduced — probably no more than 1.5 seconds in moderate weather. Diesel fuel is less volatile than gasoline and is easier to start if the combustion chamber is preheated, so manufacturers originally installed little glow plugs that worked off the battery to pre-warm the air in the cylinders when you first started the engine. Better fuel management techniques and higher injection pressures now create enough heat to touch off the fuel without glow plugs, but the plugs are still in there for emissions control: The extra heat they provide helps burn the fuel more efficiently. Some vehicles still have these chambers, others don’t, but the results are still the same."