New Audi A8 3.0 TDI Quattro

Press Release

The new 3.0 TDI engine has a turbocharger with variable turbine blade geometry. For the first time, the blades are moved by an electric actuating motor; this permits their position to be controlled more accurately. To avoid any unnecessary loss of exhaust heat, the manifolds and compensators have air-gap insulation. The combination of variable-blade turbocharger and air gap insulation ensures a spontaneous build-up of boost pressure and therefore of torque from the engine. Two air-to-air charge-air intercoolers are installed; these are mounted underneath the car’s headlights in order to obtain the best possible through-flow. To keep pressure losses and charge air temperatures to a minimum, the two intercoolers are arranged in parallel. Those were some of the main design highlights of the new V6 TDI engine.

Now for a few words about its combustion principle:

The biggest challenge was to outperform the tough EU4 exhaust emission limits in a luxury car with 6-speed automatic transmission and quattro driveline without the need for a particle filter. This called on the one hand for the very latest diesel engine technology, and on the other for special know-how in the thermodynamics of TDI engines. The 3.0 TDI is the first engine to use a completely revised Audi four-valve concept. The familiar star pattern of the valves has been modified so that each camshaft actuates two inlet and two exhaust valves. In conjunction with the controlled swirl flap, this permits the level of swirl to be extended, in other words the minimum and maximum degrees of swirl are farther apart. For the first time, the electronic swirl flap control system also permits intermediate positions to be selected. The six flaps are moved to the optimum setting in front of the spiral inlet ports in accordance with a mapped characteristic. This makes a major contribution towards keeping exhaust emissions low. At low engine speeds and loads, the minimum emissions flap is closed, so that the degree of swirl is high. At low engine speeds but when the load is high, an intermediate setting with moderate swirl significantly reduces emissions. At higher engine speeds and when peak performance is called for, the swirl flaps open fully and the degree of swirl is therefore low.