The Battle of the Big Guns at Le Mans

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As you can see from the introduction here I am writing about the LMP1 Audi R18 E-Tron Quattro and the LMP1 Porsche 919 Hybrid. I have not included the Toyota or any other LMP1 cars here because this is about 2 cars from the same parent company, with very different philosophies (although fairly similar external appearances) going head to head at LeMans.

Porsche on one hand has a Hybrid system and driveline that lends itself to Le Mans, Audi who have recenelty dropped their secondary hybrid system, have a car suited to run most other tracks in the World Endurance Series. I can already see what’s happening here. Porsche is going all out to win the big one, Audi will win the series. You heard it here. I have taken bits of info I could find from Wikipedia and Race Car Engineering in order to give you a rundown of these two contenders.

The Audi R18 E-Tron Quattro

Audi Sport has revealed its all new car built to the new 2014 LMP1 regulations in December 2013. The development of the car started in 2012. The roll-out took place in the early autumn of 2013 and a number of secret tests were conducted ahead of a private test at Sebring and its formal launch in Germany.

Audi claims that the 2014 car is the most complex race car it has ever built. The basic elements of the Audi R18 e-tron quattro’s new configuration were defined back in 2012 and the design of all the single components started at the end of 2012. The new car was rolled out in the early autumn of 2013, followed by track testing.

Audi has taken a brave decision not to compete with two Energy Recovery Systems and instead to run a single system, linked to the front axle, from which to charge up the flywheel storage system.
It is a strange choice given that Audi has worked hard to get to the full 0.5MJ release permitted by the regulations in 2012/2013, which equates to 4MJ/lap at Le Mans. Now, the limit is 8MJ and it seems likely that Toyota and Porsche will take the penalty applied to fuel consumption and run in the top class.

For Audi, to run in a lower release category means that it will play it safe, running with established systems after problems in testing. From the moment the cars started to test, there were rumours that only one system was capable of being used in the third generation R18, and it seems that Audi was never able to overcome the issue.

Audi has switched from Dallara to YCOM with its chassis supplier, as the team seeks to reduce weight and meet the new limit of 870kg for a hybrid car. ‘The next generation Audi R18 e-tron quattro represents a completely new generation of Le Mans prototypes,’ says Dr Wolfgang Ullrich, head of Audi Motorsport. ‘The principles of the LMP1 regulations have fundamentally changed. The idea behind this is to achieve similarly fast lap times as in the past with considerably less energy.’

Far from being an evolution, the V6 engine is completely new. ‘It is a brand new rulebook; the conception is completely new,’ says Ulrich Baretzky, head of engine design at Audi. ‘We could never do for 2014 what we did from 2012-2013. That would be the wrong way to go. We always have to save weight, but I don’t know how much we saved. The most important thing about the engine is that it has to last. We have saved some kilos, but we are not in Le Mans yet, tests are not finished yet, we have to wait until it is done.’

The loss of the MGU-H is less of a concern to the engine department than you might expect. ‘The MGU-H is less of an influence in the design of the engine, it is more complex in terms of overall energy management in the car,’ says Baretzky. ‘You have an amount of energy then you have to use it, and if you waste it you are lost. You have to have the management to do this, part of it by the driver, and some by the electronics.

‘The engine design methodology has not changed at all because it was always part of our job to run the engine efficiently. The only thing that has changed is the proportion; only economy or only power, and it has moved more towards economy. You have less quantities of pure performance in the lap than before to take the efficiency and to use the energy, because the energy is still used by the combustion engine, and nothing else.’
he flywheel now exactly fulfils our demands, which we have for the nw rules. Anything else would be stupid. It is the same principal, some components we took over. A hybrid system is a system. If you have an MGU with a max power of 170Kw, and a storage system capable of 100. You also need to work out how much storage do you need, and you don’t take more because it is weight.’

Audi has had another stab at improving its light system on the new generation R18 and has introduced a laser light system in addition to the LEDs that have come to be an iconic image of the car. A blue laser beam backlights a yellow phosphorous crystal lens through which the light beam is then emitted. This new light source then provides even more homogenous lighting of the road. The last time Audi introduced its super bright lighting system, it blinded the GTE drivers and was likely a contributory factor in Mike Rockenfeller’s accident in 2011.

“By using this new lighting technology Audi is setting yet another milestone at Le Mans,” said Dr. Ulrich Hackenberg, Member of the Management Board for Technical Development of AUDI AG. ‘Laser light will also open up completely new possibilities for our production models in the future.’

‘The new laser light is just one of numerous technical innovations featured by our new R18,” said Head of Audi Motorsport Dr. Wolfgang Ullrich. ‘We’re not going to reveal any more than that at this early stage, as in 2014 we’re facing an extremely tough competition and a year full of challenges for Audi Sport.’

Technical Analysis by Sam Collins
Audi’s chassis naming convention has stuck at R18, as this is the third LMP1 chassis to bear the name. The reason for this is because the Rx numbering system is copyrighted by Renault – and the R20 series and R30 series of numbers are the French firms most recent Grand Prix cars. Audi has revealed that the R18 (2014) is an all new development, whilst visually similar to the 2013 car closer inspection reveals this to be the case.

The new car features a V6 TDI engine which is said to be ‘all new’ and not an evolution of the existing 3.7 litre unit raced in both of the previous R18′s. The front mounted electric motor concept carries over from the 2013 car but the MGU itself is also new. In addition to the front motor the car features a 2014 F1 style ‘electronic turbo-compound’ layout. Energy storage is once again in the form of a flywheel though scaled up. Something that comes as a surprise as many did not believe that the technology could be scaled up adequately. It could be that Audi is not using the full 8MJ allowed, indeed it is suspected that the car is using a 4MJ hybrid system.

As in the past, a Motor-Generator-Unit (MGU), during braking events, recovers kinetic energy at the front axle, which flows into a flywheel energy storage system. For the first time, the turbocharger of the internal combustion engine is linked to an electrical machine, which makes it possible to convert the thermal energy of the exhaust gas flow into electric energy – for instance when the boost pressure limit has been reached. This energy also flows into the flywheel energy storage system. When the car accelerates, the stored energy can either flow back to the MGU at the front axle or to the innovative electric turbocharger, depending on the operating strategy.

In aerodynamic terms efficiency is the key for the new R18, the whole car is 100mm narrower with smaller tyres, this is a significant drag reduction. But the height of the car has to be increased to a minimum of 1,050 millimeters, 20 millimeters higher than before, and a larger cockpit is also mandatory, increasing drag. Interestingly Audi has not met this regulations by using a legality blister something evident on the Dome S103 and the Porsche 919.

With respect to designing the front end, the Audi engineers enjoyed new freedoms. Instead of a diffusor, a genuine front wing with a flap may be used for the first time (common to all 2014 rules LMP designs). This promises aerodynamic advantages and lower costs, as this part of the bodywork will lend itself to easier modification to suit the various race tracks. In the past, it was necessary to produce different bodywork assemblies.

On the other hand the blown diffuser used on the 2013 R18 has been banned. So the exhausts currently exit on the car centreline. It is believed that Audi has once again found a way to optimise the exhaust gasses, perhaps in an attempt to reduce drag. The chassis itself has to be stronger to be able to withstand higher loads. At the same time, it is reinforced by additional layers of fabric, which are hard to penetrate in the case of a concentrated impact. This reduces the risk of intrusion by pointed objects in accidents. Another safety change is the introduction of wheel tethers. They connect the outer assemblies of the front wheel suspensions with the monocoque and the ones of the rear suspensions with the chassis structure as is common in F1. Each of the two tethers required per wheel can withstand forces of 90 KN – which equates to a weight force of nine metric tons. Another new feature is a CFRP rear impact structure behind the transmission.
– The R18 shown off at the Audi Sport Finale party featured a curious cooling duct (below) just behind the cockpit. When asked about its function all Christophe Reinke would say is “this is not the final bodywork.”
– A look along the side of the car reveals a outlet duct apparent on the 2013 R18 has carried over, the bulge in the bodywork below the fuel flow meter connectors is of uncertain purpose.
– It has been widely noted that the front of the monocoque is much tighter and more waisted than that of the 2013 car. This section of the car also houses the front motor, judging from the size of the driveshafts it is a more potent (larger) unit than that used in 2013.
– Some early development work on the 2014 R18 was conducted at Le Mans in 2013 when Audi ran its very secret ‘black beauty’ on the test day. This car was equipped with the now mandatory narrow Michelin tyres along with some other technologies which Audi refused to disclose.
– Audi has chosen to place its mandatory air extraction holes on top of the wheel arches instead of the inner face where it is also allowed. Interestingly the design shown is very basic compared to the version run on the 2013 car

The Audi R18 e-tron quattro did not only cause a sensation on its drive through Le Mans due to its striking livery. At the beginning of a fundamentally new technological era, Audi published the key technical data of the race car’s powertrain as well. For instance, the cubic capacity of the V6 TDI power plant was increased from 3.7 to four liters in order to further optimize the engine that had already been very efficient. After testing various energy recovery systems, Audi decided to compete in the class of up to two megajoules of recuperation energy at Le Mans. The energy exclusively flows through a motor generator unit (MGU) at the front axle and is stored in a flywheel energy storage system. “We opted for this concept following extensive testing,” says Head of Audi Motorsport Dr. Wolfgang Ullrich. “In our opinion, it provides the optimum balance between efficient energy use, size, weight, energy conversion efficiency, responsiveness, drivability and a favorable operating strategy – combined with durability, which is the basic prerequisite for success at Le Mans.

The Porsche 919 Hybrid

Porsche’s return to the top category at Le Mans has attracted great excitement, and its new 919 Hybrid justifies that as it is one of the technically fascinating cars on the grid.

Whilst few exact details have been released the images and information that has come out is fascinating in itself. Overall the aerodynamic package of the car seems largely conventional, but it is certain that the final bodywork has yet to be seen, but there are some clear pointers. The car features a ‘legality bump’ in the roof (above) to allow it to meet the new minimum height regulations, something not seen on the rival Audi R18 or Adess/Lotus (also built to the 2014 chassis rules).

The cars power unit was at first thought to be a derivative of the never raced early 2014 spec Volkswagen F1 inline four engine, but recent information has revealed that this is not the case instead it is a turbocharged two litre four cylinder unit.
Videos such as the one above deliberately blur out the engine but there are clear signs that it is a V type engine. A V4 is very unusual format for a racing engine but thought to be a good one.

The engine is however known to use Formula 1 style exhaust gas recovery (electro turbo compounding) and an Audi style front mounted electric motor. Energy storage is a battery pack mounted in the passenger compartment with cells developed by A123 systems, who also supply a number of F1 teams. Not the single exhaust exit, suggesting that the car has a mono turbo layout. Porsche has released a couple of interesting videos of the car (below), from these we can glean some further technical information, such as what appears to be Cosworth Electronics equipment in the cockpit.

Porsche revealed the 919′s technical data at the Geneva Motorshow.The car will use Formula 1 style hybrid technology at Le Mans this year. In 2014 the LMP1 category has adopted a Formula 1 style fuel flow limited formula which places the emphasis on energy efficiency rather than on outright performance. Unlike in Formula 1 there is great freedom in power unit configuration in LMP1, the internal combustion engines have no air restrictors or capacity limits which has seen Audi opt for a diesel fuelled V6, Toyota for a normally aspirated V8 while Porsche has opted a two litre turbo charged V4, an unusual configuration. The turbocharger is linked to a motor generator unit in the same style as a Formula 1 MGU-H which can both act as an energy recovery system and as an anti-lag system. Whilst the second hybrid system is a front mounted MGU, similar in operation to the MGU-K in Formula 1. The front suspension layout is clear to see from the above image, rather than use the torsion bar suspension commonplace in LMP1 (and as used on the 9R6 RS Spyder) the 919 uses vertically mounted spring/damper units. The energy store is mounted in the cockpit area in the ‘passenger seat’. It is made up of battery cells from A123 systems. The very short V4 engine means that there is a very large carbon fibre bell housing ahead of the transmission (also carbon fibre). Packaging is a key issue for the new 919, and dealing with the thermal demands of the power unit is a major area of focus.