24h Le Mans
Motor racing has always given carmakers a stimulus to innovate. It has also provided a valuable platform on which to test their ground-breaking developments. This is especially true at the 24 Hours of Le Mans where reliability is equally as important as performance.
At a time when the future 24 Hours circuit was just a set of dirt tracks, a new surface was laid on the Mulsanne Straight. It combined chalk chippings with a tar/bitumen emulsion which was itself covered with tar-coated grit. By 1926, the entire circuit was surfaced. A technique that paved the way to today’s hard-wearing roads.
1925 - Aerodynamic bodies
Engineers rapidly grasped the benefits of a streamlined body. In 1925, the Chenard & Walcker Tank laid the foundations for aerodynamic research. The quest for improved drag coefficient (Cx) produced iconoclastic vehicles such as the rebodied Cadillac Coupé DeVille, dubbed “Le Monstre”, that was entered in the 1950 race. In the 1970s, Porsche developed a car shaped like an aircraft wing: the 917K (for Kurzheck, or short tail) that went on to beat the distance record in 1971 by covering 5,335.31 km. The record stood until 2010 when it was eclipsed by Audi.
It is not unusual for a part of the circuit to be shrouded in mist as dawn breaks. To overcome this problem, Lorraine-Dietrich engineers added a third lamp in the centre of the grille, earning the car the nickname “Cyclops”. Nonetheless, it probably contributed to their landslide victory: the three B3-6s took the top three places as the Robert Bloch/André Rossignol pairing exceeded a distance of 2,500 km.
In the early years of the race, the architecture of the cars doing battle was quite standardised: front engine and rear-wheel drive. In 1927 however, Maurice Fenaille, a French manufacturer, financed an innovative project pioneered by Jean-Albert Grégoire, a multi-talented driver and engineer. He designed a front-wheel-drive car known as the Tracta. It finished seventh in its first appearance at the 24 Hours of Le Mans. That same year, Citroën introduced the principle on the vehicle it named Traction.
According to Enzo Ferrari, “horses pull the plough, not push it”. It is rather ironic then that the first rear-engined car to win at Le Mans was a Ferrari 250 P in 1963. But it was not the first of its type to start the race. That particular honour goes to a Renault 4 CV, prepared and entered by a gentleman driver, Camille Hardy, against the advice of the company, which considered the car unsuitable. Unfortunately, it retired with engine trouble.
This innovation was not specifically invented for the 24 Hours of Le Mans, but the race helped forge its reputation by providing a useful testing ground. In 1951, Michelin fitted a Lancia Aurelia B20 GT with radial tyres, the patent for which had been filed just five years earlier. The introduction of textile cords into the tyre’s carcass strengthened the sidewalls and thus improved solidity and roadholding. Shod with the Michelin X, the Italian car topped the S 2.0 class and finished twelfth overall.
How to boost performance while controlling fuel consumption? In 1952, Mercedes introduced a system – originally developed by Bosch for aircraft – that was capable of improving the efficiency of petrol engines. Petrol was injected directly into the combustion chamber, avoiding fuel losses and optimising combustion. The famous 300 SL with gull-wing doors was equipped with this technology when it won in 1952.
Progress in racing car performance highlighted another necessity: improvements in brake efficiency and endurance. Jaguar discovered the solution when it equipped its C-Types with a revolutionary piece of technology: disc brakes – a solution originally developed for aircraft landing on aircraft carriers! The English make finished first and second in the 1953 race. The idea was subsequently adopted by Citroën on the pioneering DS and is still used today on all production cars.
Night-time accounts for around eight hours of the 24-hour race. Bordered by forest, a large part of the circuit is plunged into absolute darkness. Effective lighting can therefore make all the difference. In 1962, Ferrari installed halogen headlamps using iodine vapour on the 330 TRI/LM for the very first time. The test proved conclusive as the beam range was doubled and, consequently, halogen headlamps were fitted to all cars from 1965.
In 1957, the constant aim to boost innovation saw the creation of a new class reserved for gas turbine-powered cars. A 25,000-franc prize was offered for exceeding a distance of 3,600 km. In 1963, BRM fielded a strange-looking model powered by a gas turbine engine and fitted with a 220-litre kerosene tank. It’s distinctive whistling sound attracted a great deal of attention but, as it did not meet regulations, it was not classified. However, it did achieve the feat of reaching the finish line in an unofficial seventh place. All the same, attempts to apply the technology to production cars were inconclusive.
Michelin brought a major innovation to the racing world when it invented “slicks” – tyres with a smooth tread, providing greater traction on a dry track. The results were immediately obvious as the #46 Alpine A210 driven by Vinatier/Bianchi became the first P 1.6 car to lap in under four minutes while winning the class.
How can the downforce essential to stability at high speed be increased other than by working on the body design? The answer to this question came from Chapparal who introduced the first rear wing on its 2F prototype. The oversized wing – as wide as the car – looked rather comical as it sat perched high above the rear end. Chapparal had also designed a pedal system to adjust its angle for different parts of the circuit! The active rear wing was born.
A rotary engine is recognisable by the barely bearable screeching noise it makes. The technology was introduced in 1970 on a Chevron-Mazda, powered by a 200 bhp, 983 cc twin-rotor engine which failed after just four hours of the race. In 1991, however, the architecture came good in spectacular fashion. With troubles affecting Mercedes, Jaguar and Sauber, and the Peugeots putting in a disastrous performance, Herbert/Weidler/Gachot drove the rotary-engined Mazda 787B to victory – the only Le Mans win ever recorded by a Japanese marque.
The idea of supercharging through an exhaust-driven turbocompressor appeared in 1962 in the United States on the Chevrolet Corvair Monza. BMW brought the innovation across the Atlantic, adopting it on the 2002. Porsche used it at Le Mans from 1974, winning the race in 1976 with the 936.
American Don Panoz was the brains behind the idea of a hybrid engine design combining internal combustion technology and an electric motor. His Esperante GTR-1 Q9 was powered by a Ford 6.0 engine supported by an electric motor with the batteries being recharged by a regenerative braking system. Despite this technology, the Panoz Q9 failed to qualify for the race. The first hybrid car to win the race was the Audi R18 e-Tron in 2012.
Since it was invented in the late 19th century, the diesel engine has always been associated with commercial and utility vehicles as it appears to be more at home under a truck bonnet than in a racing car. However technical developments such as direct fuel injection, increased pressure and turbos have boosted performance and cut fuel consumption. The first diesel-powered car to appear at the Le Mans 24 Hours was a Delettrez in 1949, but victory only came in 2006 when Audi took the honours.
LED (Light-Emitting Diode) headlamps, increasingly popular on production cars, made their first appearance at Le Mans in 2011 on the Audi R18 TDI. In addition to offering excellent lighting quality, the distinctive lamps use less electricity, weigh less and are more compact than halogen systems. In 2014, Audi went a step further by introducing laser lights that offer even higher performance.
