PRIN. OF INTERNAL COMBUSTION ENGINES - OD1619 LESSON 1/TASK 2
(1) In a diesel engine the fuel and air mixture is ignited by the heat generated
engine. The diesel engine therefore needs no ignition system. For this reason,
the gasoline engine is referred to as a spark ignition engine and a diesel engine
is referred to as a compression ignition engine.
(2) In a diesel engine the fuel and air mixture is compressed to about one
twentieth of its original volume. In contrast, the fuel and air mixture in a
gasoline engine is compressed to about oneeighth of its original volume. The
diesel engine must compress the mixture this tightly to generate enough heat to
ignite the fuel and air mixture. The contrast between the two engines is shown in
figure 26 on the following page.
FIGURE 25. THE FOUR STROKE CYCLE DIESEL.