Intake Air Side, Air Routing

Intake Air Side, Air Routing

General

The intake systems in all new Cayenne models have been redesigned for direct fuel injection (DFI) in order to achieve a high torque curve. The air cleaner elements must be changed every 72,000 miles (120,000 km) or after 4 years according to the Technical Data.

NOTE: Air filter replacement intervals have changed for M.Y. 2008 when compared to the 2003-2006 Cayenne models.

Cayenne S Intake System







The illustration shows the intake system, from the air intakes behind the left and right headlights, the air filter housings with sound opening and the two pipe mass air flow sensors to the electronic throttle.

Variable Intake System







A new feature of the Cayenne S variable intake system is that intake manifolds of different lengths can be used due to a switching mechanism within the intake system. The variable intake system combines the advantage of long intake manifolds (for high torque in the lower rpm range) with short intake manifolds (for high specific power in the upper rpm range). A high torque curve is achieved, depending on the position of the intake manifold switching flap in conjunction with the optimised intake duct geometry.

The DME control unit activates an electropneumatic shift valve, which switches a vacuum to the diaphragm cell. The switching flaps for cylinder bank 1 and 2 are actuated synchronously via a connecting link. In the torque setting up to approx. 4150 rpm, the long intake manifold is effective with a length of approx. 538 mm, while in the power setting, at an engine speed of more than approx. 4150 rpm, the short intake manifold is effective with a length of approx. 284 mm. If the electropneumatic shift valve is not activated, the variable intake manifold remains in power position.







The variable intake system is made of a shell shaped fiber reinforced polyamide. A total of five plastic shells are welded together here. Four switching flaps are installed on a steel shaft for each bank and are coated with silicon for a reliable seal. The weight of the intake system in the 4.8 l naturally aspirated engine compared to the 4.5 l engine is reduced by approx. 10.5 oz (0.3 kg) despite the integration of the switching flaps for the variable intake manifold system.