50-hour endurance run on a bumpy track
All of the GT works pilots were given the chance to drive the first kilometres in the new 911 RSR at the rollout in March 2016 on Porsche’s test track in the Research and Development Centre at Weissach. Extensive tests were then undertaken on racetracks that were selected for a specific development task: suspension setup, tyre and brake development as well as aerodynamic validation. The highlight of the test phase was a 50-hour long run in Sebring. “As far as I know, no other manufacturer has dared to do this,” says Marco Ujhasi. The test on this extremely bumpy racetrack in Florida, known for the immense challenges it throws at man and machine, ran without any major issues. “Precisely because of the enormous stresses, it was the right direction. This was confirmed at the first two races of the season; the long-distance classics of Daytona and Sebring, where our new car impressed immediately with a strong performance.”
The new 911 RSR is powered by a cutting-edge, naturally aspirated, six-cylinder boxer engine. The displacement is 4,000 cc, with the output at around 375 kW (510 hp), depending on the restrictor. The motor features direct fuel injection as well as a rigid valve drive and is characterised by outstanding efficiency. The engine is a systematic evolution within the line of Porsche’s normally aspirated motors, which not only meets the demands of a racing engine for the 911 RSR, but also the requirements of a 911 GT3 for the road. The developers opted for a normally-aspirated powerplant, not only because it saves up to 40 kg in weight. Marco Ujhasi: “A naturally aspirated engine is a highly emotional powerplant for customers of our road-going vehicles, yet it also has the performance potential to meet the high demands of motorsport.”
Engine tests on test benches and racetracks
Thanks to the outstanding baseline engine development for the 911 GT3 R, the RSR motor ran for the first time on the test bench after about seven months. Full-scale endurance runs began after almost a year. The test programme for the engine of the 911 RSR included two 70-hour long runs under different weather conditions. All up, the engine of the 911 RSR withstood over 300 hours of endurance runs. Despite the sophisticated engine test benches, testing on a racetrack is still critical.
“On the test beds, we simulate maximum stress situations, such as a particularly fast qualifying lap on circuits with maximum full-throttle passages such as Daytona and Le Mans,” says Marco Ujhasi. “Special racing situations, like caution phases or a sudden exit from the pit lane, cannot be simulated on a test bench. These insights as well as impacts on the entire vehicle can only be gained on the racetrack.”
Extensive wind-tunnel tests
Early on in the development of the aerodynamics for the new 911 RSR, computer simulations CFD (Computational Fluid Dynamics) were carried out. These trials offered the chance to evaluate certain concepts and components without having to actually build a model. Afterwards, the concepts under consideration were tested in the model wind tunnel, in real airflow. After the model wind-tunnel trials, 80 per cent of the car was completed. The next step for the last 20 per cent was then to go testing in the large Weissach wind tunnel with a running belt. This simulates a racetrack almost identically; it can replicate entire corners to see how the car will behave on actual racetracks. These discoveries are then fed back into the computer simulation, with the help of which one can, for example, very accurately predict lap times the car would normally clock on the racetrack.
The new 911 RSR’s serviceability was significantly improved. Changes to the suspension setup can be performed much more quickly and easily, and, if necessary, entire elements of the carbon-fibre body can be exchanged completely in a very short time thanks to cleverly-devised quick-release fasteners. A door, for example, can be replaced within 15 seconds, and a front bumper with underbody can be swapped out in less than one minute. “Those who encounter these problems with a private road car,” said Marco Ujhasi, “would have to catch a taxi or a train for the day.”
The new 911 RSR is the first Porsche GT race car to be fitted with state-of-the-art assistance systems. Thanks to a radar-supported collision warning system, the so-called “Collision Avoidance System”, drivers, who are constantly being overtaken by more powerful and faster prototypes, enjoy a better view to the rear. On a monitor in the cockpit, arrows indicate if vehicles are following directly behind. Depending on the colour of the arrows, the driver knows whether the trailing car is coming closer or falling back. Not only does this system work in fair weather, but also in rain, fog and at night. A new safety cage and a new, rigidly-mounted racing seat further enhance driver safety.
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