FUNDAMENTALS OF THE DIESEL CYCLE
Diesel Engine Fundamentals
At 43 ABDC, the camshaft starts to close the exhaust valve. At 53 ABDC (117
BTDC), the camshaft has rotated sufficiently to allow the spring pressure to close the
exhaust valve. Also, as the piston travels past 48ABDC (5 after the exhaust valve starts
closing), the intake ports are closed off by the piston.
Figure 21 2-Stroke Exhaust
Figure 22 2-Stroke Intake
After the exhaust valve is on its seat (53 ATDC), the temperature and pressure begin to
rise in nearly the same fashion as in the four-stroke engine. Figure 23 illustrates the
compression in a 2-stroke engine. At 23 BTDC the injector cam begins to lift the
injector follower and pushrod. Fuel injection continues until 6 BTDC (17 total degrees
of injection), as illustrated in Figure 24.