air alone

air and fuel

air and lub oil

fuel alone

fuel pump

governor

injector

carburettor

fuelinjection starts at 10° before to dead center and ends at 20° after tor dead center

fuel injection starts at top dead center and ends at 20° after top dead center

fuel injection starts at just before top dead center and ends just after top deac center

may start and end anywhere

less difficult to ignite

just about the same difficult to ignite

more difficult to ignite

highly ignitable

250°C

500°C

1000°C

150°C