How Rule Changes Played Out at 24 Hours of Le Mans

August 1, 2014
Story By
John Brooks

The 82nd edition of the 24 Hours of Le Mans was arguably one of the most keenly anticipated in this great event's long and rich history. There were new rules for 2014, which we have been looking at over the past few months, these mandate a high level of energy efficiency. There was going to be a three way fight from well funded factory teams for the top step. The leaders would be as fast as they had been in prior years and they were going to use 30% less fuel in achieving this speed, this will benefit us all in the long term. This is relevant racing, competition that has a point beyond the visceral thrill of speed. If that is not enough, it is also Le Mans, the world's greatest motor race.

When framing the regulations, the FIA (the sport's governing body) and the ACO (who run the Le Mans 24 Hours) did not take the Balance of Performance route, instead they tried a much more complicated method, Equivalence of Technology. The reasoning behind this course was to attract as many manufacturers as possible given that they have many diverse ways of powering the vehicles that get us from A to B every day. So energy could come from both diesel and petrol, the engine lay out was open so any number of cylinders, turbocharged or not, 4 or 2 wheeled drive and a wide variety of energy recovery systems were accommodated within the fiendishly complicated regulations.

The teams are now allocated a defined amount of energy to run each lap, split between petrol or diesel and the amount of hybrid energy permitted. The fuel has been balanced using the Brake Specific Fuel Consumption - in practical terms the amount of horsepower that a gram of fuel can deliver. The BSFC has been declared by the manufacturers to the FIA/ACO and will be checked post Le Mans, but any car that exceeds 2 per cent of its declared BSFC will receive a stiff retrospective penalty.

So why this interest in reducing fuel consumption and harvesting energy? Aside from the natural inclination of engineers towards efficiency in general there has been legislation going on in the background in both North America and Europe. I wrote the following on my blog three years ago. At the end of July US President Obama announced an agreement with a broad coalition of motor manufacturers and other interested parties to dramatically increase fuel economy and reduce pollution for all new cars and trucks sold in the United States in the period from 2017 to 2025. The new standards call for incremental improvements each year in fuel efficiency to achieve a 2025 target of 54.5 mpg – almost a 100% increase on the 2011 requirements. Greenhouse gas emissions would be reduced to 163 grams per mile, approximately 50% of the current position. These are major changes and provide a huge challenge to the car industry. Where America goes, the European Union and the rest of the world will surely follow. It is held that competition is a sure fire way of fast tracking that process, diverting a small proportion of the road car budgets into the competitive arena will bring disproportionate benefits, well that’s the theory. This is the ultimate motivator for the manufacturers and the new rules at Le Mans are the result of the FIA/ACO grasping the opportunity to attract new blood with relevant competition and engineering challenges. Has this worked? Well for the most part yes. In addition to the trio contesting outright victory in 2014, Nissan announced that it will be joining in next season and others such as Honda and Ferrari are said to be waiting in the wings.

As if the challenges that the reduction in fuel consumption and the consequent new power trains were not enough, completely new designs for the cars were required. There was a reduction in weight, from 915kg to 870kg. Safety concerns brought completely revised cockpit requirements, raising the height by 20mm, and the tyre sizes had changed too.

The reduction in fuel consumption added to the pressure on the drivers, real time monitoring of the fuel flow meant adapting the driving style using techniques like coasting into corners. Deploying the huge burst of recovered energy to maximise performance and using the maximum available energy each lap added considerably to the complex task of racing. All of this threatened to overwhelm the already busy driver, information overload adding to the list of obstacles to producing the optimal performance on the race track.

The other area identified as the source of potential performance gains was aerodynamics - and during race week this was to be a constant source of friction between the manufacturers and the ACO/FIA. After the Spa FIA WEC round, it emerged that all three manufacturers were utilising some form of flexible front floor dampers ostensibly to protect the floor from damage when riding the kerbs. Of course there were also some performance gains to be had as a happy consequence of this flouting of the rules. Presented with a fait accompli the FIA gave a concession to the trio of factories with the warning that any similar attempts to circumvent the rules at the rear of car would not be tolerated. This issue would surface during race week.

There was a new, but familiar, challenger for outright victory as Porsche returned to the arena that had seen them rack up 16 wins between 1970 and 1998. They were under no illusions as to the magnitude of their task, Audi and Toyota are too good, too professional, not to be awarded the highest respect - 2014 was to be a year of learning or so they kept telling us. And of course we believed them.

Starting with a clean sheet of paper, in contrast to their rivals who have been racing LM P1 prototypes for a number of years, Porsche came up with a radically different solution utilising a 2-litre V4 engine. This was both lightweight and, perhaps more importantly compact, as packaging the energy recovery system into the confines of a race car would prove to be one of the greatest challenges. The project got off to a difficult start with a significant vibration problem with the V4 and curing this took six valuable months drastically reducing the amount of testing prior to the car's race début at Silverstone in April. The Porsche recovers its energy from a KERS system at the front and an electric motor that is powered by the exhaust gases, this gives up to 6 Mega Joules to make up for the shortfall in fuel allowance.

The delays in getting the project to the level where serious endurance testing was possible gave everyone, including the team, doubts about the durability of the cars, especially in the heat of competition at Le Mans.

The conventional wisdom from "experts" such as I was that Toyota had this race under control, at least as much as anyone can in such a huge, sometimes random, enterprise. The Japanese manufacturer had scored comfortable wins in the opening rounds of the FIA World Endurance Championship at Silverstone and Spa. The TS040 is powered by a normally aspirated 3.7-litre V8, a development of the engine that powered the 2013 car. Energy recovery comes courtesy of a double KERS system (front/rear) and this is run in the 6 Mega Joule category, giving a claimed power in bursts of nearly 1,000bhp. The package had proved to be reliable in both testing and races. If there was a year that Toyota could join the ranks of Le Mans winners 2014 was it.

Audi were discounted after Spa by the "experts," but later some of us put our racing hats on. Since arriving in 1999 Audi have taken on the mantle of being unbeatable at Le Mans, losing only three times (1999 BMW, 2003 Bentley and 2009 Peugeot). This is not a coincidence, they have won pretty, they have won ugly and they have snatched victory when they had no right to do so.

Audi have relied on diesel technology for their competition success since 2006 and have based their road car marketing efforts around this technology. It has proved to be a successful strategy as the numbers testify -sales in 1999 were 637,000, by 2013 this had increased to 1,608,000. Marching to a different drum has its consequences, the engineers calculate that running a diesel engine incurs a weight penalty of around 50 kilos. As shown with Porsche and Toyota running a system that is able to recover and use 6 MegaJoules energy is complicated, difficult to package in a racing car, and above all else is heavy.

So Audi's engineering gurus decided on a conservative strategy of using the minimum amount of recovered energy, 2 MegaJoules. When this decision was taken the numbers still favoured that route, but once the final regulations were published it was evident that that was no longer the case. However the numbers may say one thing, the real world may have another idea. The race team were given the job of making the R18, with its diesel engine and its electro-magnetic flywheel, work. It was a tall order.

The fun and games began almost straight away as both Porsche and Toyota were pushing the boundaries of the aerodynamic rules at the rear of their racers. At the Official Test Day it was spotted that Porsche had a flexible engine cover. This allowed the trailing edge to deflect as speeds increased, thereby reducing drag. The ACO were not best pleased, nor were the other competitors, so by the time that race week came around, an adjustment was made that fixed the issue.

That was just a storm in a teacup compared with the row concerning the Toyota rear wing. The problem turned out to be a rotating rear wing assembly mechanism which reduced aerodynamic drag. The offending item passed Scrutineering but this did not satisfy the other LM P1 teams, who were quite vocal in expressing their displeasure. Their arguments were given validity post race as the wing arrangement was declared as 'not acceptable at future WEC races' by the Technical Working Group. Drop back in at DrivingLine next week for the recap of how the new technologies fared during the 24 Hours of Le Mans.

How Rule Changes Played Out at 24 Hours of Le Mans

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