2008 Audi RS4 convertible

FSI delivers even better power and performance

The engine is key to the quality of any sports car. In the new RS 4, Quattro GmbH has placed its trust in a compact V8 unit featuring a petrol direct injection. In the 420 bhp high-revving eight-cylinder engine, FSI technology has reached a new high point. This is where the experience gleaned in building the equally high-revving race engine from the Le Mans-winning Audi R8 has proved invaluable. The most successful racing car in the world, with which Audi has among other things captured the title in the legendary 24-hour race in four out of the past five years, likewise featured a V8 FSI as an efficient source of propulsion that took it that decisive extra lap.

In this top product of what is an innovative yet already incredibly successful technology, the petrol is injected directly into the combustion chamber, resulting in a uniform fuel/air mixture. Thanks to the cooling effect of the directly injected fuel, Audis development engineers have at the same time being able to increase the engine compression ratio. This further enhances the engine’s efficiency.

Petrol direct injection is, in fact, the very basis of a more effective combustion process and therefore of improved power output. This is demonstrated most clearly in the engine’s more spontaneous responsiveness. Thanks to this technically highly sophisticated injection method, optimum power output is produced in every driving situation.

The figures illustrate the outstanding potential of the eight-cylinder unit. The V8 revs up to a speed of 8,250 rpm. The 4.2-liter engine already delivers 420 bhp of power output at 7,800 rpm. With its displacement of 4,163 cm3, this sports-car engine breaks through the magic barrier of 100 bhp per liter, a truly outstanding achievement for a production saloon. Peak torque is 430 Newton meters at 5,500 rpm.

And 90 percent of this maximum torque is maintained consistently throughout an impressively wide engine speed range from 2,250 all the way to 7,600 rpm.