Exhaust System: Description and Operation

Exhaust System, Emission Control

Cayenne S Exhaust System







The new Cayenne S features an enhanced exhaust system. To keep emissions to a minimum, it is important that the catalytic converter reaches its optimal operating temperature quickly. To achieve this, the exhaust manifolds in all Cayenne models are short in order to use the high exhaust emissions temperature to heat the catalytic converters.

The modified pipe guide on the exhaust manifold has also resulted in a significantly improved torque. The redesigned connection of the exhaust tracts to shorter, air gap-insulated exhaust manifolds means that the catalytic converter heats up faster due to the reduced thermal mass. The weight of the entire system has also been reduced by other measures, e.g. the use of new pre-catalytic converters and pipes with thin walls.

Cayenne S Sports Exhaust System (Optional only for Tiptronic S)










A sports exhaust system is offered for the first time for the new Cayenne S. The sports exhaust system is activated using the standard Sport button. The sound of the sports exhaust system is controlled while taking the load, speed, engine rpm and gear into account. Like the standard exhaust system up to the muffler, the sports exhaust system has two pre-catalytic converters and two main catalytic converters, the two exhaust tracts of which are linked together via a crossover pipe after the main catalytic converters.

The modified muffler in the sports exhaust system produces an sportier V8 sound. The design of the tailpipes resembles the standard dual tailpipes used on the new Cayenne Turbo. However, a connecting web gives them a unique look reserved exclusively for the Cayenne S with sports exhaust system.

NOTE: Water fording depth is reduced when the sports exhaust system is installed. Consult vehicle owner's data for specifics.

Cayenne Turbo Exhaust System







Compared to the previous model, this exhaust system has been designed specifically to suit the new DFI engine in the Cayenne Turbo.

Exhaust Manifold







This illustration shows the internal design of the Cayenne Turbo exhaust manifold. The internal design of the double-wall, air gap-insulated exhaust manifold has been further enhanced compared to the 4.5 liter engine.

Turbocharger







The two turbochargers are arranged in parallel. A low intake manifold volume, short exhaust manifold and a redesigned turbocharger that has been adapted to suit the air consumption of the 4.8 liter DFI engine ensure a good response. A new larger radial turbine is used here compared to the previous 4.5 liter turbo engine. The illustration shows the water cooled turbocharger for the right cylinder bank with the pressure unit for boost pressure control as well as the lubricating oil supply and suction lines.

Boost Pressure Control










The pressure sensor in front of the throttle valve reports the boost pressure to the DME control unit. Depending on the current required and actual boost pressure, the DME control unit activates the cycle valve for boost pressure control according to a pulse/duty factor. This modulates a control pressure, which adjusts the bypass valves (-W- wastegate) on the turbochargers via the pressure units for boost pressure control in order to regulate the boost pressure.