Audi R8 LMS: Second model cycle optimized for customers

Since 2015, the second generation of the Audi R8 LMS has been setting standards in terms of lightweight design, safety and aerodynamic efficiency. In many areas, the evolution that has been available since the end of 2018 presents itself even better than the previous model. The development of the second model cycle was primarily focused on a single objective: to modify the successful GT3 race car in ways that suit the needs of customer racing drivers even better than before.

For the development of the current race car, the engineers led by chief developer Armin Plietsch addressed four areas to achieve their objectives: aerodynamics, brake cooling, the clutch and the transmission. “We deliberately chose to make moderate modifications instead of pursuing a comprehensive evolution,” says Chris Reinke, Head of Audi Sport customer racing. “This is economically sensible for both new customers and for those teams that are able to easily retrofit their existing cars with all new components.”

At the front, modified body styling and a new splitter have not only represented a new face but also aerodynamic improvements since 2019. While the parameters for aerodynamic drag and downforce are specified by the FIA (Fédération Internationale de l’Automobile) the new shape makes more consistent downforce possible across diverse ambits. Varying ride heights that the teams achieve due to suspension setups, as well as driving conditions at different speeds or in situations like braking in front of corners and while accelerating, now have smaller effects on airflow. This leads to higher aerodynamic stability which makes for a steadier handling feel particularly for gentleman race drivers. Following the CFD calculations, Audi Sport tested the new components in the 50-percent wind tunnel and subsequently validated the results in tests. In addition to pros, amateur and gentlemen drivers were included in testing at an early stage. They confirmed that the direction of the development has resulted in appreciable progress.

In the area of brake cooling, the engineers targeted higher consistency as well. Improved airflow to the rear brake system and more efficient evacuation of hot air from the ventilated disc brakes prevents the wheels from overheating in racing operations. Due to the physical correlation between pressure, temperature and volume, these innovations are conducive to achieving more consistent tire pressures. This is another factor that enhances the consistency of the race car. In addition, optimized airflow through the front bumper improves brake cooling at the front axle.

In terms of power transmission components, Audi Sport improved the three-plate racing clutch. Wear protection for the clutch spring extends the rebuild interval of this highly stressed component by more than 50 percent. The other drive train elements have become more durable as well. Revised gear teeth and reinforced bearings make longer running times of the sequential six-speed transmission possible. In addition, the engineers managed to reduce the influence of wear-prone differential discs. By using a softer preloading spring wear can largely be compensated for, so that the locking effect will not diminish even on long runs. These advantages are particularly effective in 24-hour races because even after a continuous racing distance of several thousand kilometers, vehicle balance is maintained.

While these innovations made their world debut at the Paris Motor Show in October 2018, customers receive a concept that has perfectly proven its viability in all other areas. The chassis of the production model and the race car directly derived from it have been built in the same facility at Audi Sport GmbH at Böllinger Höfe since September 2015. The final assembly of the race car is performed at the customer racing site in Biberach.

In terms of safety, the current generation of the Audi R8 LMS plays a pioneering role, having clearly surpassed the requirements of the regulations ever since its launch. Thanks to a modified structure of the front end and a carbon fiber reinforced plastic (CFRP) crash element being used for the first time at the rear, the GT3 sports car fulfills the crash test requirements for Le Mans prototypes (LMP). The sophisticated Audi Sport Protection Seat PS03 with its structural stiffness and adaptability to various driver physiques is setting standards in seating technology. It is firmly connected to the chassis, which increases stiffness. A rail-mounted, easily adjustable foot lever unit and a height- and length-adjustable safety steering column enable various adjustments to the respective driver. By introducing the rescue hatch in the roof of the kind used in DTM race touring cars Audi was a pioneer in GT3 racing in 2015. Following a crash, the hatch makes it possible to pull off the driver’s helmet upward in a way that is gentle on the spine and to apply a KED (Kendrick Extrication Device).

Lightweight design is another one of Audi’s areas of expertise. In spite of the additional weight resulting from the aforementioned innovations, the race car’s dry weight is clearly lower than before. The homologation weight that has been reduced compared with the first generation of the Audi R8 LMS can easily be achieved even in endurance racing trim with additional headlights and air conditioning for the helmet and seat. The intelligent material mix of aluminum in the Audi Space Frame (ASF) combined with the structural CFRP center tunnel and the CFRP back wall as well as the steel roll cage make the chassis alone about 30 kilograms lighter than that of the first generation – since 2015, it has tipped the scales at merely 252 kilograms. At the same time, the torsional stiffness of the supporting frame has increased by 39 percent.

Although the race car features a more complex material mix, Audi has interlinked the manufacturing process of the production car and the race car even more closely than before. At a manufacturing facility at the Böllinger Höfe industrial park in Heilbronn, Audi Sport GmbH jointly produces both chassis variants. In spite of the race car receiving modified cast-aluminum nodes and a steel roll cage, the racing chassis of the R8 LMS remains integrated in the basic production process up to and including the point of roof assembly and cathodic dip painting (CDP), which is a type of priming. Only after these process steps, the race cars are completed at the Heilbronn-Biberach site.

Audi uses production parts in the R8 LMS wherever they make technical and economic sense in racing. The V10 engine with 5.2 liters of displacement and up to 430 kW (585 hp) of output in racing is produced on the same assembly line as the production unit. It remains nearly unchanged and, with a scheduled service interval of 10,000 kilometers and rebuild interval of 20,000 kilometers, sets standards in racing. The designers use modified or completely new assemblies only where they are required by motorsport regulations or by the significantly higher loads encountered in on-track competition. For instance, the production ASF chassis is only modified while the new bodywork consists of CFRP. Installed in the suspensions are wishbones that are strictly designed for racing. Fielding in the customers’ hands has proven the durability of the overall construction. Teams that are active in customer endurance racing completed more than 75,000 kilometers in practice, qualifying and racing operations with individual chassis of the Audi R8 LMS in less than three years.

The high aerodynamic efficiency of the race car is illustrated by some comparative figures. Thanks to a fully lined underfloor and a conceptually integrated rear diffusor the engineers managed to reduce the size of the rear wing profile by 25 percent compared with the previous Audi R8 LMS ultra while the FIA-specified maximum downforce continues to be achieved. In many racing series, the engine output of the Audi R8 LMS is limited to slightly more than 367 kW (500 hp). Even so, the model achieves better lap times than its predecessor.

The Audi R8 LMS has proven its viability as an all-round race car for customer racing around the world. It meets the challenges posed on all race tracks in all climatic zones, has won titles in Saudi Arabia as well as in Central Europe, Asia, Australia or New Zealand. The model has been successful in sprint competitions around the globe as well as in 12-hour races in Malaysia, Australia, and in the Gulf 12 Hours or in the 24-hour classics at the Nürburgring, at Spa, in the GTD class at Daytona, and in Dubai. The long service intervals enable economical operation and thanks to its racing qualities and high safety the Audi R8 LMS is equally popular with pros and amateurs.