Exhaust System: Description and Operation

Exhaust System - Panamera Turbo

There are a number of differences in the exhaust system of the V8 turbo engine compared with the exhaust system of the V8 naturally aspirated engine. For example, the pipes of the exhaust system on the Panamera Turbo have wider cross-sections than those in the exhaust system of the V8 naturally aspirated engine. This results in comparable exhaust gas speeds in both exhaust systems. The branch coupling connection installed in the V8 naturally aspirated engine is omitted for the V8 bi-turbo engine. For the latter, perforated pipes are routed through a common chamber of the center muffler. These have the same effect as a branch coupling connection. As with the V8 naturally aspirated engine, the rear muffler of the V8 turbo engine is installed visibly as a design element.













The exhaust emissions leave the Panamera Turbo through two twin tailpipes in matt silver which differ in design from the tailpipes of the V8 naturally aspirated engine. Unlike the tailpipes of the Panamera S/4S, these tailpipes are rectangular. Optimum sound is achieved in all engine speed ranges through specific insulation and pipe routing in the rear muffler as well as by means of specially designed tailpipes.

The exhaust system of the V8 turbo engine automatically switches between two operating states: as a result, there is a low noise level in the lower rpm range, and this increases in the high rpm range and at full throttle due to improved throughput. The improved throughput is achieved by opening the exhaust flaps located on one of the two exhaust pipes between the rear muffler and tailpipe cover in each case. This opens the second exhaust pipe in each muffler.







Exhaust Manifold and Catalytic Converters

A single-piece exhaust manifold turbocharger module made of high-temperature-resistant cast steel without intermediate flange has been realized for the first time for the Porsche V8 engine.







The cylinder bank-specific LSU oxygen sensors ahead of the catalytic converter and LSF oxygen sensors behind the catalytic converter signal the exhaust gas composition to the DME control unit. The DME control unit can then use this information for targeted intervention in bank-specific mixture control. This ensures that the strictest emission standards are met or even bettered - for the Panamera Turbo: EU 5 in Europe and LEV in the USA.







Turbochargers

The two turbochargers are arranged in parallel. The compact exhaust manifold turbocharger modules for each cylinder bank are adapted to the engine and ensure good responsiveness in combination with the compact intake manifold volume. A small intake manifold volume, short exhaust manifolds and newly designed turbochargers adapted to the air requirements of the engine ensure good responsiveness. At the same time, the degree of form freedom allowed by this design makes is possible to realise flow-optimized cross-sections and ensure minimum pressure loss in front of the turbine.







The DME control unit regulates the boost pressure by activating the electric boost pressure control valve (installed on the left next to the electronic accelerator). This modulates a corresponding control pressure onto the diaphragm cell (2) for activating the wastegate valves (3) on the turbochargers.