A further look at elements of Audi’s new generation 3.0L TDI diesel
16 May 2014
|The new generation TDI delivers more power and better fuel efficiency. Click to enlarge.|
Audi presented the latest generation of its 3.0 TDI diesel engine at the 35th International Vienna Motor Symposium. (Earlier post.) The new 3.0-liter engine is designed to be utilized in both MQB (transverse) and MLB (longitudinal) architectures within the larger Volkswagen Group. (This could open up an interesting application in an MQB-based mid-size Volkswagen-brand SUV.)
The exhaust-turbocharged V6 will come in two versions: 160 kW (218 hp) and 200 kW (272 hp). It features a 90‑degree cylinder bank angle and a displacement of 2,967 cc. Peak torque is as much as 600 N·m (442.5 lb-ft) depending on the model. Although the new 3.0 TDI is more powerful than its predecessor, it is—again depending on the model—as much as 13% more fuel efficient.
|Power and torque of preceding generation 3.0L TDI. Click to enlarge.||Power and torque of new third-generation TDI. Click to enlarge.|
The engineers improved efficiency, power and lowered emissions through weight reduction (optimized timing/drive chain); stronger materials enabled a hollowed camshaft and other weight reducing element and increased pressure both in terms of piston and oil pump as well as being able to operate at higher temperatures on the exhaust side of the turbo to reduce particulates/emissions.
|Integration of the new exhaust aftertreatment unit. Click to enlarge.|
Among the elements of interest in the new engine is the close-coupled exhaust gas aftertreatment system. Audi combined a NOx storage catalytic converter with a diesel particulate filter and SCR injection in a single assembly.
The entire unit is integrated into the engine package, and satisfies the most stringent of emissions legislation, including the Euro 6 standard. It also reduces CO2 emissions by an average of 15 grams (24.1 g/mi).
To enable integration of the new aftertreatment unit, Audi redesigned the chain drive, making it smaller and thus providing more packaging space for the exhaust gas handling unit.
|Stages in the development of the exhaust aftertreatment technology. Click to enlarge.|
The piston rings and pins have been optimized for minimal friction; the rings have a PVD/DLC (physical vapor deposition/ diamond-like coating) and the pins, DLC. That, combined with other changes in the cylinder crankcase, reduces friction torque by up to 10% at higher engine speeds, compared to the outgoing generation.
The oil circuit, with a variable pressure oil pump, is thermostatically controlled.
The crankcase and the newly designed cylinder heads have separate coolant loops; the cylinder head has a two-piece water jacket (upper and lower) . The updated, innovative thermal management system improves efficiency even further.
The air-handling system of the new generation TDI includes new optimized intake and exhaust channels in the cylinder head; a new exhaust gas turbocharger with variable turbine geometry (VTG); and cooled EGR.
|A simplified cartoon of the variables in Audi’s model-based air handling system. Click to enlarge.|
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