2020 Audi S7 Sportback TDI Engine

The 3.0 TDI that powers the new S models** is the latest, extensively enhanced development stage of the V6 diesel engine. In the S6 Sedan, S6 Avant and S7 Sportback, its 2,967 cm3 cubic capacity produces 257 kW (349 metric horsepower) power output and 700 Nm (516.3 lb-ft) torque (Combined fuel consumption in l/100 km: 6.5 – 6.2*; Combined CO2 emissions in g/km: 171 – 164*). This torque is available from 2500 to 3100 rpm. The specific output is 117.9 metric horsepower per liter of engine capacity, and the specific torque is 235.9 Nm (174.0 lb-ft) per liter. In the Audi S4, S5 and SQ5, the key figures are 255 kW (347 metric horsepower) and 700 Nm (Combined fuel consumption in l/100 km: 6.8 – 6.2*; Combined CO2 emissions in g/km: 177 – 161*).

The V6 diesel engine, which works at high ignition pressures of up to 205 bar, boasts sophisticated high-tech components in all areas. The pistons are made of highly heat-resistant aluminum material and has revised geometry. The connecting rods and crankshaft have been adapted accordingly. An enlarged wheel set boosts the efficiency of the oil pump, while additional cooling plates in the oil cooler ensure improved cooling capacity. The water-cooling circuits of the crankcase and cylinder heads are kept separate so that the engine oil warms up rapidly from a cold start. This substantially reduces friction losses and, therefore, fuel consumption. The heads have dual-section water jackets. In their upper section, the coolant circulates more slowly than in the hard-working lower section. As a result of this solution, flow losses are reduced and the water pump needs less drive energy.

The large turbocharger develops up to 2.4 bar relative boost pressure—it can push through up to 1100 kg (2425.08 lb) of air per hour. Its variable turbine geometry (VTG) is optimized for low-loss flow. The additional low-pressure exhaust-gas recirculation, which is active in most driving situations, extracts the exhaust gas behind the components of the emissions control system and reintroduces it in front of the compressor. Consequently—in contrast with purely high-pressure exhaust-gas recirculation—it allows the turbocharger to be powered with the full mass flow, thus making it much more effective. With the high rates of recirculated exhaust gas, combustion takes place at lower temperatures, resulting in significantly reduced NOx raw emissions.

The common rail system is also a major factor in clean emissions. It injects the fuel through eight-hole nozzles at pressures of up to 2500 bar. In each cycle, it can perform up to seven separate individual injections. This means fine atomization and clean, precise combustion. The new S TDI models* are certified according to the Euro 6d-temp emission standard (68 mg NOx/km).

The performance diesel engines benefit from near-engine exhaust gas aftertreatment, with three modules working in tandem: The NOx oxidation catalyst stores the nitrogen oxides until it is full. Cleaning is by means of mixture enrichment in the engine. To minimize the related extra fuel consumption, the catalyst kicks in especially at low exhaust temperatures.

Once the operating temperature is reached, the second module of the system—the SCR-coated diesel particulate filter—takes care of NOx conversion in most driving conditions. Its enhanced SCR coating also guarantees stable conversion of nitrous oxides to harmless nitrogen at high loads—for instance when pulling a trailer. The AdBlue solution that facilitates the conversion. A downstream SCR catalyst is the last component of the emissions control system.