Exhaust System: Description and Operation
Exhaust System
The new 911 Turbo features a newly developed exhaust system. Despite larger catalytic converters and additional air-gap insulation of the manifolds, the weight of the entire exhaust system has been reduced by approx. 4.4 lbs (2 kg) (approx. 7 %) thanks to the further improvement of individual components. In addition, the new exhaust system offers lower flow resistance for better engine performance.
Due to the new position of the turbochargers, the exhaust manifolds have a new shape, but with the same diameters. The air-gap insulation, which was only partly used where the pipes came together in the predecessor, has now been extended to include the complete manifolds. This improves heat management after a cold start.
The one-piece component package found in the previous model, comprising the main muffler and the right-hand and left-hand catalytic converters, is no longer used in the new 911 Turbo. The stainless steel rear muffler has the same shape and internal structure as the one in the 911 GT2 (997). This has allowed the volume for the new 911 Turbo to be significantly reduced compared with the rear muffler of the previous model and the pipe diameter to be enlarged from 60 mm to 65 mm. Overall, these measures result in a reduction in weight and lower flow resistances for better performance and a more powerful engine sound.
The new 911 Turbo, like its predecessor, has stainless steel, chrome-plated tailpipes integrated into the rear apron as a characteristic design element and as a reference to the Carrera GT. Compared with the previous model, the tailpipes have been considerably enlarged and their shape modified. The now funnel-shaped tailpipes and smaller visible gap between them and the compensating trims of the rear apron make the tailpipes appear even better integrated in the rear apron of the new 911 Turbo and support the powerful rear design.
Exhaust System Components
- Exhaust manifold (AK) has new shape and is completely air-gap insulated
- Catalytic converters and rear muffler as individual components
- Catalytic converters each with two ceramic monoliths
- VK - Primary catalytic converter
- HK - Main catalytic converter
- Compact rear muffler (S) based on 911 GT2
- New larger tailpipes (E)
Catalytic Converters
Instead of one monolith for each catalytic converter as in the previous model, the new 911 Turbo now features two identical ceramic monoliths with an enlarged diameter on each side of the vehicle. This enables a reduction in the flow resistance for high performance figures and a larger effective catalytic converter surface for converting pollutants more efficiently.
Emission Control
The 911 Turbo complies with the following emission standards in combination with direct fuel injection (DFI) and secondary-air injection:
- EU5 for Europe
- LEV II/LEV for USA
Despite the increase in power, the new 911 Turbo complies with the strict EU5 emission legislation valid in Europe. Compared with the EU4 standard, the tightening of the emission standard includes above all a reduction in nitrogen oxides (NOx) by 25 %. This is supplemented by extended durability and stricter monitoring of the emission control and monitoring components with earlier fault indication in the instrument cluster (European On-Board Diagnosis - EOBD).