End of the road for Porsche’s 919 Hybrid

In July 2017, Porsche shocked the motorsport community when it announced the end of its top tier prototype racing program a year early, in order to prepare for a move to Formula E. After returning to the World Endurance Championship and the 24 Hours of Le Mans in 2014, Porsche and its 919 Hybrid frequently visited podiums and victory lanes. Three consecutive overall wins at the 24 Hours of Le Mans starting in 2015 highlighted the Porsche 919’s mark on sports car racing.

Before the surprise announcement, the race team in Weissach was busy planning for another year of racing. Leaving a year earlier than planned left Porsche with commercial partners to consider, a team with energy and ideas for another year, and a gap before Formula E would become a reality.

The Concept

A proposal emerged shortly for a tribute version of the 919 for demonstration drives, static displays, and to generally generate visibility in 2018. Weissach is full of creative engineers and their minds started to wonder what might be possible. After all, development for the aborted 2018 campaign was already in process and it would be a shame to leave those ideas on the shelf.

If an updated version of the 919 would only be used for exhibition and marketing purposes, why not discard the rulebook and its arbitrary limits and requirements? Why not show what an unrestricted Le Mans prototype could do on a race track? The basic 919 platform could be retained and a budget would still constrain modifications to some degree, but an evolved 919 would show what was possible without the constraints of competition regulations.

The Timeline

The first technical meeting took place in September 2017, resulting in a formal proposal to the Board to further develop the 919 and chase specific lap records as a proof statement. The concept echoed the top speed record run of the 917/30 at Talladega in 1975.

The Board considered a variety of proposed challenges. Some they liked and some they did not. The team could not undertake any actual work until authority was granted. The last World Endurance Championship race of the 2017 season took place at Bahrain on November 16-18, 2017. Formal Board approval arrived the day after the race and work started immediately.

Two key milestones were established for the effort. First, Porsche would chase the ultimate pole position lap record at Spa Francorchamps, held at the time by a Formula One car. With a gap of about 11 seconds between LMP and Formula One pole lap times, making up this amount of time would be a major accomplishment. Second, the 919 would target the overall lap record on the Nürburgring Nordschleife. With so much history over the decades, the Nordschleife is a second home for Porsche. In addition, Porsche driver Stefan Bellof steered his Porsche 956 in 1983 to a lap time record that had never been challenged around the iconic north loop.

The Board supported the project but not at any cost or any risk. The 919 would not be converted into an entirely different beast, but rather have its basic platform optimised where feasible. For example, the base chassis, engine and powertrain would not be modified but settings for fuel flow, engine mapping and aerodynamics were fertile grounds for finding speed.

Likewise, tyre technology was an avenue to optimise. Single-lap qualifying tyres had been banned by regulation in top tier motorsport since the 1980s. Tyre supplier Michelin eagerly joined the project and developed bespoke single lap qualifying special tyres to handle the increased demands of downforce while improving grip.

The world first became aware of a 919-farewell tour on December 9, 2017 when Porsche included a mention, along with other updates released in conjunction with its annual “Night of Champions” gala in Weissach. Only a few sentences buried towards the end of a lengthy press release made reference to the project with no hints that outright lap records would be pursued.

After several months of work, long-time Porsche factory driver Timo Bernhard first took chassis #1704 to the Weissach test track on 14 January 2018 to shakedown the newly developed version of the 919. Chassis #1704 ran as car #1 in the 2017 Le Mans 24 Hours and sadly retired from the lead on Sunday morning with a commanding lead. The chassis served as a spare monocoque for the remainder of the 2017 season. (Its “T-car” stickers still remain on the car). After further development, such as wind tunnel testing in late March, the car completed another run in Weissach with Bernhard at the wheel on 4 April.

The Record Runs

Only a few days later, the team unleashed Swiss driver Neel Jani to chase the track record at Spa Francorchamps for the car’s first outing at speed on a racetrack. With the benefit of a few days of testing to refine the car for Spa, Jani posted an outright lap record on 9 April of 1 minute 41.77 seconds, about three quarters of a second faster than Lewis Hamilton’s 2017 Formula One pole time. The time was about a dozen seconds faster than the pole time set for the race specification 919 in 2017 as well.

Jani’s time exploded across the internet and the project was first publicly identified as the “919 Evo.” The speed clearly illustrated the Le Mans prototype regulations’ focus on fuel efficiency rather than pace, a fact that got the attention of the racing regulators at the FIA as well. The Porsche Board also realized that the engineers at Weissach had eagerly turned the 919 into a land missile rather than merely an interesting marketing display. The incredible pace raised enough eyebrows that a subsequent outing at Spa was cancelled, so we’ll never know if the stopwatch would have conceded further seconds.

The 919 Evo’s time atop the speed charts only lasted for a few months. Subsequently, Sebastian Vettel set a pole time at the 2018 Formula One Spa Francorchamps race edged Jani’s time by three tenths of a second.

The Spa outing for the 919 Evo was not a public event, so most people only saw official photos on social media. Porsche changed that by taking the 919 Evo to the Nürburgring 24 hours on 12 May for its first public appearance. The car was displayed in the paddock on the morning before the start of the race along with the museum’s 956-005 for the event.

The 919 Evo was open for all to see and the crew answered question after question. In a world where racers zealously protect every edge and technical advantage, the transparency was refreshing. Just before the race, Timo Bernhard drove the 919 Evo and Hans Stuck piloted the 956 for a slow speed parade lap around the full Nürburgring Nordschleife in front of thousands of enthusiastic spectators and their cameras. Porsche was coy, but the parade lap only supercharged speculation whether Porsche was going to make an attempt to break Stefan Bellof’s lap record at the Nordschleife.

Bernhard made six or seven laps at the Nürburgring Nordschleife during a brief afternoon test on 4 June to dial in key settings such as a much higher ride height than Spa due to the Ring’s notorious bumps. Porsche returned on 29 June with a gaggle of press, sufficient tyres for several runs, and Bernhard ready to drive for a shot at the lap record.

In addition to his years of experience at the Nordschleife, Bernhard prepared for the run with many simulator sessions and strict instructions to stay off the curbs, skip the bumpy Karussell, and avoid getting the car airborne over the bumps. The bumps were a major concern. At high speeds with enormous aerodynamic loads, excessive air under the nose of the car could quickly become catastrophic.

The day was dry, but warmer than typical. In all, Bernhard made four runs. The first was an acclimatisation lap that didn’t use the special Michelin tyres. The second run clocked a 5:31, smashing Bellof’s time by 40 seconds. The car bounced more than expected and suffered from understeer, so the team made adjustments and send Bernhard out for another attempt. The changes made a big improvement and Bernhard sliced off another 6.5 seconds en route to a 5:24.5 lap time.

At this point, driver and engineer had a candid conversation. Bernhard felt like he was flying a fighter jet through a tunnel on sections of the track lined with trees. Could he go faster? Yes. Did he want to? Harder question. Was the team starting to take too much risk? After all, the lap record was a distant memory and nobody wanted the disaster of a flying car flipping into the woods.

Naturally, they decided on another run. With a few minor adjustments, Bernhard exited the pits for the final attempt. Five minutes, 19.46 seconds later the Porsche 919 Evo made history. Bernhard parked the car in pit lane and told lead engineer Stephen Mitas, “That’s it – not doing that again.”

The Road to Retirement

With the successful mark set at the Nordschleife had accomplished its mission. Demonstration runs were organised for the Brands Hatch and the Goodwood Festival of Speed. Porsche ran briskly but declined the opportunity to chase outright time records. Nick Tandy came within a tenth of a second at Brands Hatch with very little prep and nothing on the car optimised for the occasion. Likewise, in September, the 919 Evo reported for duty at the Rennsport Reunion VI hosted at Laguna Seca Raceway in California.

At Laguna Seca, the 919 Evo was a crowd favourite and attracted a steady stream of admirers and cameras throughout the weekend. Earl Bamber lapped within 2 seconds of the track record in his first 919 Evo laps. The car was not optimised for the demonstration runs. It had the potential to smash the record but Porsche opted to leave the record unmolested.

After a filming day on Pacific Coast Highway for Porsche in Big Sur, the battery was drained and the car flown back to Germany. After final preparation at Weissach, 919 Evo chassis #1704 drove at slow speed to its final retirement destination in Zuffenhausen at the Porsche Museum.

The Technology

The 919 Evo’s additional speed comes from a variety of areas. Unnecessary weight was the first thing to go. Headlights, air conditioning, pneumatic jack, and even the windshield wiper were stripped to save about 86 pounds. Aerodynamics was the biggest visible transformation. The nose was reprofiled and air evacuation gills and openings on top of fenders were eliminated. The rear bodywork, wing and diffuser were lengthened and optimised. Underneath, the floor was redesigned to maximise downforce.

Porsche added a drag reduction system which manipulated two dive planes beneath the nose in conjunction with laying down or standing up the rear wing horizontal element. In addition, the track map was programmed into the car, enabling the drag reduction system to shift settings for downforce in the corners and low drag in the straights. The car also incorporates driver inputs to avoid making aero adjustments at inopportune times. Aside from the electronic controls, the driver can always override the drag reduction system via a button on the steering wheel. Bernhard didn’t touch the button on his record Nordschleife lap.

Side skirts were added to better control the air at ground level as well. The team didn’t want to change the bodywork too much but did experiment with moving skirts. They abandoned the idea after determining that sliding skirts would create aerodynamic instability. Fixed skirts were installed, but quickly became disposable after rubbing against the pavement and curbing. The skirts are one of many examples of modifications that could have been pursued further but doing so would have required significant modifications to the body shape.

The Weissach magicians impressively managed a package that generated drag similar to a Le Mans car but with more downforce than a high downforce configuration. In certain corners, the race configuration of the 919 had been constrained by grip rather than power. Reducing drag in these corners was a key to reduced lap times. The aerodynamic changes also cured slow speed understeer that was previously unresolvable.

The added downforce required strengthening of the suspension and the power steering. Of course, strengthening meant adding weight but safety made it mandatory. Without power steering enhancements, the increased downforce of the 919 Evo would have required the driver to back off to manage the car through fast corners. Packaging was extremely tight which required a clever tandem pump solution for the power steering system.

A four-way brake-by-wire system was added to permit individual actuation of each wheel. Regulations otherwise limited such actuators to one per axle. Managing torque and braking for individual wheels as needed, even mid-corner, helped to address understeer and avoid locking up the inside rear wheel under braking. A “pitch link system” previously precluded by regulation helped to keep the car’s ride height as low and stable as possible.

Porsche abandoned the fuel efficiency regulations and maximised fuel flow. Horsepower from the internal combustion 2-litre V4 engine driving the rear wheels jumped from 517 PS to 720 PS. The electric motors driving the front axles was also given a boost from 400 PS to 440 PS. Together, the total power peaked at 1160 PS which represents an increase of about 27% more than the car ran in race specification. Drivers were able to hammer down for the full lap without concern for fuel flow restrictions or pit stops or needing to gently “sail” the car to conserve fuel. Again, the constraints of the exercise to keep the basic engine and hybrid system and prevented the engineers from tinkering too much with the engine or taking advantage of other fuel mixtures. If tweaks were permitted on engine parts like the turbo and piston design, horsepower numbers could have skyrocketed even further.

While Michelin produced bespoke tyres to handle the increased downforce and provide as much grip as possible, there were constraints. Porsche stayed with 2017-spec wheel sizes which meant Michelin stayed with 2017 tyre dimensions as well. Michelin found more grip but tyre pressures needed to increase as well due to the downforce.

As it was, the tyres were targeted for cooler temperatures rather than the unseasonably warm and humid conditions that greeted the team at the Nürburgring. With higher tyre pressures, higher temperatures and a very soft compound designed only for a single lap, the tyres became greasy toward the end of the 20.832 km/12.94 mile lap and were difficult to handle. The one-lap special tyres produced a significant improvement as compared to race spec tyres but further development and budget and optimal weather conditions might have found yet more time.

Comparing a Formula One car and the 919 Evo, the Formula One car still would enjoy an advantage in the corners. Tighter and more twisty corners play to the agility advantage of the Formula One car. In faster sweep corners and straightaways, the 919 Evo makes use of its aerodynamic advantages to enjoy the edge over a Formula One machine. On a track like Spa that is relatively smooth and features high speed sections, the two are evenly matched. On the Nürburgring Nordschleife, the advantage likely would fall to the Formula One car in the slower and twisty bits before the 919 Evo claws back the advantage as the track straightens out towards the end of the lap. In fact, the 919 Evo was equipped with the tallest Le Mans gearing in the Porsche parts bin but still ran out of revs on the long Dottinger Hohe straightaway at the Nürburgring. Gearing of the hybrid motors on the front axles was yet another area that could have yielded additional pace with more development and budget.

One surprise discovered by the team during the Nürburgring record runs was broken bump rubbers in the rear suspension after every run. The bruised bushings were a mystery until a few weeks after the record run when the team discovered photographs taken trackside showing the car with four wheels off the ground at Pflantzgarten 2. The force exerted on the car as it returned to the track was sufficient to shatter the rubber discs. Without the rubber pieces to cushion the vibrations, the car hit the hard stops on the rear suspension under compression which excited the front axle as well. If you’re interested, look at the on-board footage from about the 4:12 mark into the run, and watch how much Bernhard’s head moves around from that point, particularly on the long Dottinger Hohe strait.

Man versus Machine

The 919 Evo is both a marketing and engineering exercise. The objectives of the project were to show the capabilities of a Le Mans prototype. That objective, together with budget discipline, inherently limited the magnitude of technical changes. The Porsche Board agreed to the project with certain goals in mind but did not want to develop a completely different platform or seek records at any cost. Even if the 919 Evo could have been developed to go even faster, the process of human driver preparation and development would need to adapt and progress as well. Nevertheless, the program gave the LMP race team at Weissach a chance to continue the 919 development program, and lay a foundation for future Porsche road and race cars. It also gave a chance to give a proper farewell to the 919 program and memorialise the names of the hundreds of people involved on the red stripes across the bodywork. The 919 Evo now is a permanent resident of the Porsche Museum collection, so it has taken its place in the timeline of Porsche history and will greet guests for years to come.

NOTE: The author gratefully acknowledges the time and assistance of Stephen Mitas, lead engineer for Porsche on the 919 Evo project.

Written by: Kevin Ehrlich
Images by: Kevin Ehrlich, Porsche Werkfoto & Virtual Motorpix/Glen Smale