24 Hours of Le Mans: Racing cars use 30 percent less fuel


Racing cars use 30 percent less fuel

The final test for the Le Mans racing car

On Easter Sunday at twelve o’clock, the starting signal for the endurance world championship will be given in Silverstone, UK. The highlight of the racing series is the Le Mans 24 Hours in mid-June. The "world" observed the teams’ last day of testing before the start of the season.


It’s almost boring: everyone comes to the Le Mans 24-hour race, but Audi always wins. Now there is finally another opponent: Porsche is only taking part because it is about saving fuel.

W.hen the Ferrari comes by, it always gets particularly bad. Then it seems as if there is a turbo charger for sound waves, so quickly and relentlessly they rush down the ear canal and then hit the eardrum hard. The Ferrari sound grinds along the pain threshold, that’s for sure.

But despite all acoustic efforts: The Italian sports car brand is not the focus of interest at the World Endurance Championship, which begins on Easter Sunday in Silverstone. This also becomes clear on the last day of the test: Here in Le Castellet, France, everyone just watches what the big three are doing: Audi, Toyota and – for the first time after a 16-year break – Porsche.

These teams will fight the world championship among themselves, and one of them will also be the winner at the highlight of the season, the 24 Hours of Le Mans. In both the World Championship and Le Mans, four types of racing cars will take to the track at the same time. The near-series sports cars like the Ferrari 458 have no chance against the prototypes, which include the Audi R18 e-tron quattro, Toyota TS040 and Porsche 919 Hybrid.

It’s about speed and fuel consumption

A tidy Wolfgang Hatz enters the room, the development board of Porsche AG takes a look at the monitor with the lap times: The big three are not very far apart.

Porsche is still the record winner at Le Mans with 16 titles, at the same time the manufacturer from Stuttgart is the big unknown this year: Normally you can’t win as a newcomer, but the rules have changed so radically that in 2014 the cards were reshuffled for everyone will.

“The newly created and revolutionary efficiency regulations were decisive for our step,” says Porsche boss Matthias Muller about the return to endurance racing. Because it’s no longer just about who is the fastest. This year you can only win if you are fast and at the same time use very little fuel.

Additional attraction: Although the regulations are long like a coalition agreement, they promote the fight for the best technology more than in Formula 1.

870 kilograms with up to 1000 hp

While the drive technology is the same for everyone in the premier class of motorsport, the endurance teams have a lot more freedom. How big the engine is, how many cylinders it has, whether it runs on gasoline or diesel, a great deal is approved. What is fixed, however, is how much fuel the cars have to get by with.

No LMP1 car may consume more than 5.04 liters per race lap in Le Mans. The lap is exactly 13.629 kilometers long, resulting in a maximum consumption of 37 liters per 100 kilometers.

That sounds like a lot, but for a racing car with up to 1000 hp that is driven at the limit, that’s not much. Compared to the Le Mans race in 2013, it is even 30 percent less.

These savings can be achieved with even more consistent lightweight construction (the cars weigh only 870 instead of 905 kilograms), improved aerodynamics, a modified transmission (now seven instead of six gears) and of course with hybrid technology, i.e. with the addition of an electric drive.

One liter of fuel is saved every five laps

However, since batteries cannot be recharged at the socket during the race, sophisticated recuperation strategies are needed – the car has to convert kinetic energy into electricity while driving and temporarily store this energy before it is called up again for acceleration phases.

There were already delicate approaches to this last year, but these were limited by very strict regulations. For example, the cars were allowed to recuperate a maximum of 0.5 megajoules of energy per race lap in Le Mans (this corresponds to 0.016 liters of petrol or 0.014 liters of diesel), and the electricity generated was only allowed to be accessed at the exit of a few precisely defined bends and above a speed of 120.

Those days are over, now drivers can use electricity where and how they want, and cars can also provide them with more electrical energy.

The teams have to choose two, four, six or eight megajoules per round. The more electrical energy a car can use, the less petrol or diesel it can consume.

Cheating is practically impossible

The fuel requirement is not only stipulated by the regulations, it is also monitored with a flow meter. Cheating is forbidden and would not bring any advantage: Those who consume more than allowed have to refuel more often and lose a lot of time.

Porsche developed the 919 Hybrid in such a way that it falls into the six megajoule category, which means that it saves around one liter of petrol every five laps (with around 350 laps to be driven, that’s 70 liters per race, a little more than a full tank of fuel). Porsche is the only team to have two energy recovery systems on board.

Like the cars of the competition, the 919 Hybrid recuperates when braking, but it also uses the hot exhaust gases. They not only drive the turbocharger, but also a generator, which then also feeds electricity into the lithium-ion cells.

Audi had a similar system under development, but does not want to use it. The R18 e-tron quattro is therefore classified with two megajoules and can use a little more fuel per lap.

Audi forfeits diesel advantage

Although there is a fundamental difference between gasoline and diesel racing cars: Since diesel contains more energy per liter, the Audi regulations only allow a 54.8 liter tank, while Porsche and Toyota use 66.9 liters each.

Theoretically, the Audi can stay on the track for 13.46 laps, compared to its six megajoule petrol competitors 14.17. According to these values, all LMP1 favorites come to the pits to refuel after no more than 13 Le Mans laps. The reserves at Porsche and Toyota are likely to be too small to risk another fast lap.

In the meantime, Audi has essentially forfeited its diesel advantage. The company has competed at Le Mans since 1999, with a diesel engine since 2006, and so far Audi has won Le Mans twelve times. In the beginning, among other things, because you can continue driving on diesel fuel and need fewer pit stops. This advantage is now gone thanks to individual tank sizes.

What all three competitors have in common is that they direct the extra electrical energy to the front wheels (Toyota gives it to the front and rear wheels) and briefly turn their racing cars into four-wheel drive cars. During the test at Le Castellet, it was very easy to see that the cars accelerate out of tight corners without running the risk of drifting.

Toyota has the most powerful engine

On the other hand, it is not possible to judge from the outside whether the driver actually boosted with electrical energy. He can do that when he thinks it’s right, and the already difficult job of a racing driver has not become any easier. He now has to think about when to use the additional energy and what for: to overtake or to accelerate out of a curve.

The fans on the track, at Le Mans there are regularly a good 250,000, but they can look forward to an exciting decision. Audi has the greatest experience, Toyota the highest performance with around 1000 hp, and Porsche is the new team that everyone will be watching anyway.

“Le Mans is the biggest motorsport event in the world,” says Wolfgang Hatz. And then he still speaks of a vision: "This endurance world championship should be something like in the 1970s, when it was perceived as being as strong as Formula 1."

The wish is understandable in view of the high sums that Porsche and everyone else are spending on their Le Mans commitment. We are talking about three-digit million amounts. “In absolute terms, we certainly have the smallest budget,” says Hatz, “but it is the largest in relation to sales. That’s why I have to get something back for it. "

"The Porsche 911 remains a six-cylinder"

The Chief Development Officer speaks of the know-how for engineers, of the transfer of technology to production vehicles – which is what they say when you’ve released a lot of money for car racing.

On the other hand, the beating heart of the Porsche 919 Hybrid is not a small four-cylinder with a displacement of just two liters for nothing. Exactly such engines, spurred on by turbochargers, will be used in the small Boxster / Cayman sports car series in the near future. "We are also working on the four-cylinder for series production," confirms Hatz, but it is still too early for more detailed information. "For the Boxster and Cayman I don’t have any problems with that."

Only a Porsche 911 will not be available with a four-cylinder engine. "No, that is my sanctuary, it remains a six-cylinder." Nevertheless, the four-cylinder does not have to be restricted to the small sports cars. Why shouldn’t a Porsche Macan, the medium-sized SUV, also be able to drive with a turbo four-cylinder??

"The plug-in hybrid will be the solution"

You will get closer to the series product if you talk to the Head of Development about hybrids and, above all, plug-in hybrids – that is, the hybrid with larger batteries that can also be charged at the socket. "I’ve been on the road for five years because it was already clear to me at the time: the plug-in hybrid will be the solution for the next ten or 15 years."

Even if there is no socket waiting in the pits for the racing cars: The complicated interplay between the combustion engine and electric motor under racing conditions, the recuperation process – Hatz wants to use all the knowledge from the several-hour races for the series. “Nobody can take the learning effect away from us. That is money well invested. "

The trip to the test day of the Le Mans racing cars was supported by Porsche. You can find our standards of transparency and journalistic independence at www.axelspringer.de/unabhaengigkeit

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