Fuel Injection:

Figure: Fuel Injection

Fuel in a liquid state is injected within the cylinder at a precise time and rate to ensure in which the combustion pressure is forced on the piston neither too early nor too late, as displays in Figure. The fuel enters the cylinder whereas the heated compressed air is present; therefore, it will only burn while it is in a vaporized state (attained by the further of heat to cause vaporization) and intimately assorted along with a supply of oxygen.

The first minute droplets of fuel come in the combustion chamber and are fast vaporized. The vaporization of the fuel causes the air surrounding the fuel to cool and it needs time for the air to reheat suitably to ignite the vaporized fuel. But once ignition has begin, the further heat from combustion helps to further vaporize the new fuel entering the chamber, as long as oxygen is present. Fuel injection begins at 28° BTDC and ends at 3° ATDC; thus, fuel is injected for duration of 31°.