The Road to Le Mans

The new endurance racing season has begun. The Porsche 919 Hybrid is lighter, stronger, faster, and more reliable. All new materials were fine-tuned for competitiveness in the test-drives.

Porsche and Le Mans—it’s a love story. Speaking of Le Mans, tough men wax misty-eyed about magic, goosebumps, tears, desperation, and ardor. Their recollections rise like an apparition, casting strange shadows on the presence of the listener. Without experiencing it, you can never understand this race.

“And then I go and spoil it all by saying something stupid like I love you”—grand sentiments can miss the mark, as Frank Sinatra and his daughter Nancy sang knowingly. And yet, while an entire self-help industry gamely tries to squeeze love into a guise of objectivity, things are decidedly easier when it comes to Le Mans. For beyond the feelings, it also has a goal-oriented technical angle to consider.

At Porsche, that aspect is the responsibility of Alexander Hitzinger. As the technical director of the LMP1 program, he’s responsible for the prototypes with which Porsche is starting in the big leagues in its second season since its comeback. LMP1 stands for Le Mans prototypes of Class 1—a closed race car for the FIA World Endurance Championship (WEC), with the 24 Hours of Le Mans taking place on June 13–14. The LMP1 regulations call for hybridization and directly link the performance of the prototypes to their energy efficiency.

Hitzinger and his team have put that evolutionary impulse into practice. While it may sound like adjusting a few screws here and there, in fact it meant that even as the basic concept was retained, every detail of it was re-examined. The 919 Hybrid still features a downsizing turbo gasoline engine with direct fuel injection and two energy recuperation systems. Total system output is now almost 735 kW (1,000 hp). The list of enhancements is long.

The combustion efficiency of the now lighter and stiffer two-liter four-cylinder engine increased again. The load-bearing function of the 90-degree V-engine in the chassis also added to overall stiffness through geometry modifications. To improve performance and achieve more efficient aerodynamics, a twin exhaust system replaces the central exhaust tract in the previous version. The combustion engine powers the rear axle with well over 368 kW (500 hp). With the critical sequential and hydraulically actuated seven-speed racing transmission as well, the team managed the balancing act of reducing the weight while simultaneously achieving greater stiffness and robustness. “At the same time, we also reduced the shifting times yet again,” adds Hitzinger.

More power and less weight is the result of the comprehensive reworking of the hybrid system. On the front axle, kinetic energy is converted into electric energy during braking. The second recuperation system is in the exhaust tract. The exhaust flow drives—practically parallel to the turbocharger—a turbine.

The electricity generated this way, like that from the front brakes, is temporarily stored in lithium-ion battery cells. The driver can then call up the energy from there. When he needs full boost power, additional force to the tune of 294 kW (400 hp) presses him into his seat. This power is directed to the front axle via an electric motor and converts the 919 into an all-wheeler.

When it comes to using electric energy, the drivers face a choice: if they largely drain the battery in a duel by boosting somewhere on the lap, they might be left behind on the straightaway if a competitor still has some reserves. The greater the amount of electric energy that a driver can apply per lap, the lower the amount of fuel he is allowed to use. The rules thus promote innovative hybrid technology while leveling the playing field between the different concepts.

The Porsche 919 Hybrid has been homologated in the highest megajoule class for the first time in 2015 and can add eight megajoules of boost per 13.6-kilometer lap, but can use only 4.76 liters of gasoline. For a 1,000-hp race car that drives at full throttle for 70 percent of the time and reaches speeds of 335 km/h on the straightaway, that’s revolutionary. The prototypes consume some 30 percent less fuel than in 2013—and yet are still faster than their predecessors.

The sandwich-design carbon-fiber monocoque, which is now manufactured in a single piece instead of two, is notably lighter and yet stiffer. “That’s down to improved layer construction,” explains the technology expert. He would never compromise in terms of safety. And that approach has paid off: less than half an hour before the first victory of the previous car at the season finale in Brazil, Mark Webber emerged from a hair-raising crash almost entirely unscathed.

In terms of aerodynamics, efficiency objectives were joined by sensitivity concerns: lower susceptibility to wind, steering angle, float, and roll angle. These disruptions change the airflow around the car, compromise stability, and thus reduce speed. Aerodynamicists always have a twofold problem at Le Mans: the long straightaways require such low drag that downforce has to be kept to an absolute minimum. On the other sections, however, more downforce is needed.

It’s getting loud again. With its new twin tailpipe setup, the 919 sounds even more imposing. Nico Hülkenberg shifts into seventh gear, boosts, and kicks up a storm. Marc Lieb, the fastest symbiosis of passionate race-car driver and engineer, watches the sand eddies. What does it mean to start with this new Porsche at Le Mans? Lieb smiles in the darkness and shakes his head. “It’s impossible to describe. You just have to feel it.”

By Heike Hientzsch
Photos by Jürgen Tap

The three driver teams are subject to exacting standards.

The drivers of the two trios from last year remain unchanged: Timo Bernhard (Germany), Brendon Hartley (New Zealand), and Mark Webber (Australia) now have starting number 17. Car 18 will be driven by Romain Dumas (France), Neel Jani (Switzerland), and Marc Lieb (Germany). In Spa and Le Mans, Earl Bamber (New Zealand), Nico Hülkenberg (Germany), and Nick Tandy (UK) will share a third prototype with starting number 19.

Fritz Enzinger, head of the LMP1 program (photo), has full confidence in all nine drivers: “It goes without saying that each of these drivers is fast and clever. But in the WEC, and especially in Le Mans, there are even more qualities that count. The ability to stay focused constantly and to deliver consistent performances is a musthave for endurance racing. Another important factor is the ability to work together and integrate what one has learned.”