Fuel Injector: Description and Operation

Fuel Injectors/High Pressure Injectors







The electromagnetically operated fuel injectors are on the intake side of the cylinder head. They are activated by the DME control unit in accordance with the firing order. Following activation, they inject fuel directly into the combustion chamber at a pressure of 580 psi (40 bar) to 1740 psi (120 bar). During this process, a vortex is created even before the fuel emerges at the valve tip.

The Cayenne S and Cayenne Turbo are equipped with different injectors, designed specifically to suit the engine's fuel requirements. The injectors can be differentiated by their part numbers and a color marking. The piston recesses in the V8 naturally aspirated engine and the V8 Turbo are also different so that the injected fuel can be whirled around and mixed perfectly with the air that is drawn in.

Fuel Injectors - V8 Turbo

At a fuel pressure of 580 psi (40 bar) and an injection time of 0.6 ms, the amount of fuel injected is approx. 7.8 mg/stroke. While at a fuel pressure of 1740 psi (120 bar) and an injection time of 6.1 ms, the amount of fuel injected is approx. 107 mg/stroke.

In addition to the amount of fuel injected and the injection time, the shape and alignment of the fuel jet is also important.







Retainers For Fuel Injectors






The four retainers -NH- for the two injectors ensure the following:
- Installation as a pre-assembled unit with injectors installed.
- Twist-lock protection for screwing on fuel lines.
- Exact installation position for aligning the fuel jet in the combustion chamber.
- Correct pretensioning of the fuel injectors in the cylinder head.
- Vibration damper for reducing the transmission of vibrations from the cylinder head to the injectors.