Audi RS 4
The 2008 Audi RS 4 developed by Audi AG’s performance tuning division quattro GmbH, break new ground in the sport sedan and convertible segments. These high-performance models feature numerous innovations, delivering top performance on both road and track.
At Audi, the “RS” designation stands for unmatched performance ability, technological innovation, motorsports pedigree, and thrilling driving dynamics. At the heart of the RS 4 is the high-revving 420-hp naturally-aspirated V8 engine featuring FSI direct injection technology, which was first proved out in the Le Mans-winning Audi R8 prototype race car.
The RS 4 features the latest generation of the quattro permanent all-wheel drive system with asymmetric/dynamic torque distribution. Under normal driving circumstances, 40 percent of the power is sent to the front wheels and 60 percent to the rear. This new asymmetrical torque split quattro system is key to achieving the RS 4’s sporty driving dynamics and also ensures Audi’s legendary all-weather traction and sure-footed handling ability.
The car has been engineered to reduce excess weight, with the result being a weight-to- power ratio of 8.7 lbs. per hp (9.7 lbs. per hp for Cabriolet). The RS 4 is a unique, intelligent, high-performance vehicle with superior drivetrain qualities, offering driving dynamics unmatched by any other car in its segment.
At the heart of any sports car is the engine, and for the RS 4 quattro GmbH placed its trust in a compact V8 unit featuring gasoline direct injection technology, referred to by Audi as FSI. With FSI, gasoline is injected directly into the combustion chamber, resulting in a uniform fuel/air mixture. Because of the cooling effect of the directly injected fuel, Audi’s development engineers have been able to increase the engine’s compression ratio to 12.5:1, thereby boosting horsepower.
The RS 4’s FSI technology trickled down from Audi’s motorsports efforts. Gasoline direct injection was developed for and proven out in the Audi R8 prototype race car, a five-time winner of the legendary 24 Hours of Le Mans endurance race.
This more efficient combustion process achieves even higher power output, which is demonstrated most clearly in the engine’s responsiveness throughout the rev-band. Thanks to this sophisticated injection method, optimum power and torque output are produced in every driving situation at both low and high speeds.
At 7,800 rpm the 4.2-liter engine delivers 420 hp, and peak torque is 317 ft. lbs. at 5,500 rpm. No less than 90 percent of maximum torque is maintained consistently throughout a wide range of engine speeds from 2,250 to 7,600 rpm. Performance on the road is equally impressive: the RS 4 sedan and Cabriolet accelerate to 60 mph in 4.6 seconds and 4.8 seconds, respectively. At 155 mph the vehicle’s speed is smoothly limited by an electronic control system.
Audi has deployed the high-revving engine principle for the first time in the RS 4, which has a maximum engine speed of 8,250 rpm. The significant advantages of this principle are superior power output at high engine speeds and a smooth, eager responsiveness across the entire rev range. Further amplifying the high-performance experience is the high-revving V8 engine sound that enthusiast drivers live to hear.
For further enjoyment of the V8 sound system, pressing the “Sport” button on the dashboard produces a more aggressive engine exhaust note. Moreover, the electronic throttle control heightens its response to throttle inputs for a more sporty driving experience.
Getting all this power on to the road obviously was a significant challenge, one that was solved by incorporating the quattro permanent all-wheel drive system. Over a quarter century’s experience and market leadership in the all-wheel drive car segment represent genuine benefits for Audi’s customers. The RS 4 features quattro all-wheel drive with asymmetric/dynamic torque distribution.
Source: Audi press