Inside Porsche's 919 hybrid LMP1, and a closer look at the competition
By Mike Hanlon
March 5, 2014
For motorsport enthusiasts, 2014 is shaping as one of the most exciting years ever because Porsche is returning to World Championship Endurance Racing after a 16 year absence, and thanks to some intelligent reframing of the regulations, the battleground is now not just one of outright performance, but of technological excellence.
New World Endurance Championship rules focused on encouraging hybrid drives, engine downsizing and energy efficiency have thrown three automotive giants into a pitched battle to prove their technological expertise in the harshest environment possible.
Audi has won the Le Mans 24 Hour Race 12 times in the last 14 years – it started racing just after Porsche stopped. The world’s largest automaker, Toyota, is throwing it's massive weight behind its hybrid contender after showing much promise in its first two years of endurance competition. Both the Audi and Toyota are relatively known quantities, and now the all-time great Porsche name is returning with one goal in mind – WINNING!
It’s a script written in motorsport heaven.
Audi's 2014 R18 e-tron Quattro
Audi will field three teams in its 2014 R18 e-tron Quattro, powered by a 3.7 litre TDI (turbo diesel) V6 with an electric turbocharger, a flywheel accumulator system built in conjunction with Williams Hybrid Power and an exhaust heat recovery system which captures the thermal energy from the exhaust and can add power to either the turbocharger or the flywheel accumulator system. Knowing that Porsche was coming in 2014, the company has been preparing for this almost as long as Porsche has.
Only a week after the World Championship winning 2013 Audi R18 e-tron quattro’s last race in December, the 2014 LMP1 car was cutting laps at Sebring race track in Florida. Audi’s e-tron brand is being increasingly rolled out on the hybrid road cars which generate the company’s profits and the R18 is the brand’s champion. In its 14 years of endurance racing, the company’s race team still smarts at the two Le Mans victories which it missed. Losing is unacceptable.
Toyota's 2014 TS040 Hybrid
Toyota will field two teams in its TS040 Hybrid in 2014, powered by a 3.4 liter V8 with energy stored in a Nisshinbo supercapacitor. This year’s car will have an Aisin AW motor/generator on the front axle, in combination with the DENSO unit at the rear, meaning it now has four wheel drive and four wheel regenerative braking for the first time.
Toyota is the world’s leading manufacturer of hybrids having sold six million hybrid road cars since the launch of the Prius in 1997. It wants to win just as much as Audi, and it has massive budgets. Intelligent low emission vehicles are core to Toyota’s future as the world’s leading provider of mobility – it sees winning at Le Mans as critical to developing global recognition for its technological prowess.
Porsche's Endurance Racing Heritage
“Porsche is Le Mans and Le Mans is Porsche” proclaimed the press release for the 919 Hybrid as it was shown for the first time at the Geneva Motor Show yesterday, and it offers an insight into how seriously Porsche is taking its return to Circuit de la Sarthe (Le Mans).
Porsche has won outright at Le Mans 16 times, with 101 (other) class victories since it won a minor class just three months after the first Porsche cars rolled off the production line in 1951. Those winning ways in the world’s most famous motor race in particular and in sports car and endurance racing in general, are responsible for the performance capabilities of the brand. They embody the reason why Porsche enthusiasts worldwide are proud to be associated with the name.
Porsche’s heritage can be recounted by motorsport enthusiasts with the model numbers of legendary race cars that have taken victory there: the 917 (the 919’s nomenclature is a nod to that car), the near indestructible 935 and the 956/962 series are motorsport bywords so ingrained in modern culture that even non-enthusiasts will recognize those numbers.
The Porsche hybrid 919 is expected to race competitively against the all-conquering Audi juggernaut with a world of attention focused upon it. No-one expected Toyota to be competitive when it entered the fray and it surprised everyone by winning several races in both seasons it has competed. Porsche will not be forgiven for failure – anything less than winning will be a black mark on a pristine racing pedigree.
Indeed, Porsche won’t be prepared to settle for anything less than first place, not least because it considers hybrid automobiles to be Porsche territory. Ferdinand Porsche developed the world's first hybrid car, the Lohner-Porsche Semper Vivus (above) 114 years ago and the company is well down the road to developing a complete range of hybrids too, with the likes of the 918 Spyder sports car, Panamera Gran Turismo and all-wheel drive Cayenne.
Porsche readily acknowledges that the 919 Hybrid is the most complex race car it has ever put on wheels. It is both an LMP1 racer and as it pointed out to the press in Geneva, a “test laboratory that is subjected to the unrivaled innovative and competitive pressures of motor sport.”
Going racing has always been Porsche’s way of proving new ideas. In the Porsche psyche, racing has “maximum relevance when it comes to the future of sports cars,” as evidenced by the factory’s first sports car being sent to race at Le Mans back in 1951, just months after the company was founded.
Ever since that first 24 hour campaign, the knowledge acquired in competition has been quickly integrated into the company's road cars. Developments such as dual ignition, disc brakes, dual-clutch transmission and hybrid drives were proven on the racetrack before being introduced into production models. In its press kit, Porsche actually listed the technology which had been passed on to its road cars (below).
With Porsche returning to the top category of endurance racing, particularly with the new framing of regulations, that pipeline of technology to road cars is likely to increase its flow of benefits to the end user. Indeed, there are now four manufacturers using endurance racing to both promote and develop exciting new technologies that are highly relevant to the road cars of the near future – Porsche, Audi, Toyota and Nissan.
Nissan's ZEOD RC is not a contender for outright honors yet, but its unconventional trapezoidal ZEOD RC might yet yield even more relevant expertise by going the even longer route to competitiveness.
The newly formulated regulations for the World Endurance Championship have suddenly taken it from a race with relevance to motorsport enthusiasts and the elite few who can afford a Ferrari, Porsche, Audi or some other brand of very expensive sports car, to something the whole world will find significant and quite fascinating.
From now on, the sporting performance of the LMP1-H prototypes will be rated in direct relationship to their energy efficiency. While the allowable fuel quantity per lap has been reduced by around 30 per cent compared to last year, the amount of energy of the obligatory hybrid systems that can be used in the race has dramatically increased.
The pressures on the drivers who will pilot the fastest cars and contend for outright honors in the 24 hour races of 2014, have now also increased.
Audi's output of fascinating insight into its race efforts is worth reading. From one of its recent bulletins: “Reproducing lap times with accuracy down to a tenth, has long been a hallmark of professional race drivers such as ours,” says Head of Audi Motorsport Dr. Wolfgang Ullrich. “But in 2014, we’re making even higher demands on our WEC drivers. Lap by lap they have to meet an exact consumption target while continuing to battle for the best position on track."
Two examples of the new requirements: Only a limited amount of energy per lap may be fed into the car’s powertrain through the hybrid system – 2, 4, 6 or 8 megajoules per lap at Le Mans, depending on the class. If these limits are exceeded, 10-, 40- or even 60-second stop-and-go penalties threaten in the case of repeated violations.
The same penalties apply if the permissible amount of fuel per lap is repeatedly exceeded. Likewise, the fuel flow rate and the engine’s boost pressure are checked. “For drivers and engineers, it’s crucial to understand the complexity of the new rules and to apply this knowledge to racing situations in an optimum manner,” explains Leena Gade, who as a race engineer for Audi, won the Le Mans 24 Hours in 2011 and 2012. “This requires a flawless information flow. We’ve got to keep the drivers informed of whether they’re staying within these limits over the radio.”
The Audi Sport squad has successfully been testing this. If a driver is slowed by a vehicle heading into a turn, it may be advantageous to initially follow this car to save fuel and to only overtake it exiting the corner. But approaching a turn more gently also has effects on the car’s handling. “The drivers are no longer putting the tires and suspension under load as systematically as before,” says Leena Gade based on her observations. “That’s why the car’s dynamic response is different.” To Audi factory driver Lucas di Grassi, who was involved in the tests of the new car at an early stage, the new task poses an intriguing challenge. “It doesn’t seem like I’d have to fundamentally change my driving style now,” says the Brazilian. “Even in the past there were situations in which we had to watch our fuel consumption in order to put certain race strategies on track. Now we’re driving as fast as possible without ever losing sight of the set consumption limit. And if we do exceed the limit once, then we’ve got two laps to compensate for the excess by reducing our consumption. So here’s another challenge being added to our task list which means we’ve got to be both efficient and fast.”
Do fans have to fear that the race drivers in 2014 will be acting with great restraint in order to save energy? “Not to worry,” says Lucas di Grassi. “Even though consumption may heavily vary, the lap times are very similar and that’s why we’re running at similar speeds. It’s basically about saving a lot of energy in some sections – for instance by lifting earlier – without driving a lot slower on a whole lap. I’m impressed about how well and precisely Audi Sport has already been handling these tasks and is always able to help us with specific calculations and advice. Our sport will continue to be great fun. It’s just that we’ll be using a lot less energy in it than ever before.” The development of the Porsche 919 Hybrid began in mid-2011, designed from scratch to be the most balanced solution to this incredibly complex equation.
The Porsche 919 Hybrid
The 919 Hybrid is hence the result of a carefully balanced overall concept. From the combustion engine to the energy recovery systems, chassis and running gear, aerodynamics and driver ergonomics, the sum of all these individual components serves one goal: maximum performance within tight energy expenditure constraints.
Without any legacy designs, Porsche has chosen a much smaller engine than the V6 and V8 engines of its competitors. The two liter petrol engine is almost half the capacity of its rivals, and will spin at close to its maximum 9000 rpm for 24 hours of racing, with every bit of performance wrung from its modest displacement using direct injection and a single turbo charger.
The tiny Porsche V4 features two separate energy recovery systems. The first recovers thermal energy from exhaust gases using an electric generator powered by the flow of exhaust gasses. The second hybrid system utilizes braking to convert kinetic energy into electric energy which is stored in water-cooled lithium-ion battery packs.
Under acceleration, the front generator is operated as a single electric motor and drives the two front wheels via a differential. This gives the Porsche 919 Hybrid a temporary all-wheel drive system, because the petrol engine directs its power to the rear wheels in a conventional way.
Intelligent management of this additional available energy assumes a special role here. Of course, the strategic focus of the racing engineers is always on the most efficient use of available power. This means an optimal lap time. The driver can choose from several automated drive modes that have an effect on vehicle dynamics as a function of the traffic situation, course layout and weather conditions. At this point, the developers made use of knowledge gained by Porsche with the 911 GT3 R Hybrid, including at the 24 Hour race on the Nürburgring.
The allowable petrol fuel consumption depends directly on the amount of electrical energy that the driver can call up per lap in what is known as the "Boost" function. Race rules distinguish between four levels ranging from 2 to 8 megajoules (MJ). Porsche is developing the 919 Hybrid for the "Premiere Class" with an energy recovery capacity of 8 MJ. This requires the use of high-performance energy recovery and storage systems, which necessarily need to be larger and heavier. A flow meter device also limits the amount of fuel flow. For example at Le Mans, the turbocharged petrol engine, which is driven at full load for 75 per cent of the 13.65 kilometer lap, only has 4.64 liters of fuel available. In the 2-MJ class, the figure is 5.04 liters.
The new race regulations have reduced the minimum vehicle weight by 30 kg to 870 kg compared to last year, and hence reducing the overall weight of the car to near that figure was paramount. Porsche has approached this target by intensive optimization of even the smallest of details.
The chassis of the 919 Hybrid is a carbon fiber monocoque with a sandwich construction. It combines low weight with a very high degree of torsional rigidity and safety. As a result, it offers a foundation for precise wheel location via multi-link suspension – an important pre-requisite to exploit optimally under all conditions the full potential of race tires from development partner Michelin that are just 14 inches wide (down from 16 inches last year).
According to the race regulations, the Porsche 919 Hybrid must not exceed a length of 4,650 mm and a height of 1,050 mm, and the vehicle width must be between 1,800 and 1,900 mm. The car's aerodynamics have been fine-tuned in over 2,000 hours of wind tunnel testing since February 2012. Aerodynamics make an important contribution to the overall efficiency of the race car and reduce air drag while supplying the increased cooling air needed for the hybrid drive and the downforce needed for high cornering speeds. The aerodynamic design of the Porsche 919 Hybrid can be modified for different course characteristics.
As the season goes on, we're likely to get more access to how Porsche, Audi, Toyota and Nissan have gone about solving each new technological challenge. The parts of all of these cars are now set. The focus between now and the first week in June will be manufacturing these parts to the closest possible tolerances, assembling them under time-constrained conditions again and again, with the crew practicing the replacement of them should the unthinkable occur and one of them should fail in the race.
Nothing is left to chance. In 24 hour racing, each team's computers are running simulations continuously. Racing at this level is very close to the information intensity of the modern battlespace ... the only difference is that no-one is shooting at you.Share
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