While many of its rivals have adopted turbochargers in their quest to boost performance without significantly increasing fuel-consumption, Audi has decided to focus on supercharging technology for its latest V6 engine. Its latest forced-induction engine displaces 3.0L and produces a peak output of 290hp (213kW) and 310lb-ft (420Nm).
Combining both supercharging and direct-injection technology, the high-tech V6 carries the ‘TFSI’ designation and goes into production later this year. Audi engineers have gone with an Eaton roots-type supercharger and a front-mount intercooler. Inside it, two four-vane rotary pistons counter-rotate at a speed of up to 23,000 rpm, with an air gap between them measuring just a few thousandths of a millimeter. The rotors can deliver 1,000 kilograms (2204.62 lb) of air per hour and force it into the combustion chambers at a boost pressure of up to 0.8bar.
Audi's Michael Fitzen explains that a supercharger was chosen because of the available power at lower revs than compared with a turbo and that a low-rev, torquey nature was better suited for its luxury sedan models.
The compressor is so compact that it easily fits inside the 90-degree V of the cylinder banks, in place of the intake manifold. Because it is driven by the engine via a poly-V belt, its full thrust is available from idle speed upwards, producing huge pulling power when driving off. The gas paths after the compressor are also very short, which means that torque is built up extremely quickly.
Fuel consumption is also impressive, with an average economy rating of 23.5mpg (10L/100km) for the mixed cycle when installed in most Audi sedan models.
