24h Le Mans
24 HOURS CENTENARY – PERPETUAL INNOVATION ⎮ Carmakers in the 1950s and early sixties gave a great deal of thought as to how turbines could be used to drive motor vehicles. At the time, their use on aircraft was becoming increasingly widespread and many an engineer harboured hopes of applying the technology to terrestrial vehicles, especially for motorsport and, of course, the 24 Hours of Le Mans.
A turbine consists of a rotor equipped with blades that rotates inside a stator. An upstream (or peripheral) combustion chamber produces hot air that causes the rotor to spin and thus generate a rotary motion that drives a shaft.
The turbine’s primary advantage is that there is no need to convert the reciprocating movement of pistons to a rotary movement to drive the gearbox and wheels via a crankshaft system, as found on traditional engines, since the turbine generates the rotary movement directly. There is therefore very little friction as the rotor is equipped with rolling bearings instead of sliding contact bearings on the crankshaft, and there is no piston friction on the cylinders (via the piston rings). Consequently, there is next to no vibration. Finally, turbines work perfectly in all temperatures with almost anything that burns, mixed with air: petrol, diesel, paraffin, oils, etc.
The downsides of this technology – weight and fuel consumption – were expected to be mitigated with rigorous development specifically for the automotive industry.
The many advantages encouraged manufacturers to conduct research throughout the 1950s and introduce prototypes such as the French-made Socema Grégoire, followed by the Renault Etoile Filante, the Chrysler Turbine Car from the USA, and the UK's Rover Jet 1. Rover was the indeed the first carmaker to attempt the 24 Hours of Le Mans with a gas-turbine engine.
In line with the ACO’s commitment to showcase new technologies at the 24 Hours of Le Mans, the race organiser offered a 25,000-franc purse if any car driven by a turbine covered more than 3,600 km during the event.
As Rover was already clued up on such engines through its work on the Jet 1, the firm took up the challenge in 1963. Rover worked with the manufacturer BRM – the 1962 Formula One world champion with Graham Hill – for the chassis and came to preliminary testing in April with an unpainted body.
Powered by a Rover turbine with an output of approximately 150 hp, it soon produced reasonably quick lap times and a peak speed of 250 kph. Naturally, Hill and American Richie Ginther, BRM’s F1 drivers, were somewhat disgruntled with the lack of engine braking and the sluggish acceleration out of the turns, but it was fuel consumption that proved to be the greatest drawback for the aluminium-coloured car, subsequently painted green for the race.
It therefore had to be fitted with two 110-litre fuel tanks, instead of the statutory single one. The ACO, aware of the stakes, allowed the Rover to run in the Experimental class outside of the official 24 Hours classification and assigned it the number 00 to indicate this to the spectators. The crowd was enthralled by this car that whooshed like a jet aeroplane among the growling V8 and V12 machines. For safety reasons, the turbine-driven Rover-BRM set off 30 seconds after the rest of the field. However, it more than held its own, covering 4,172 km at a remarkably consistent pace. Had it been classified, it would have clinched an outstanding seventh place behind an all-Ferrari top six.
Rover took two years to integrate all the lessons learned from this first appearance and get a new car ready for the 1965 race. Work on reducing fuel consumption by fitting a heat exchanger meant that a single 110-litre tank sufficed and the car could enter the regular field with the number 31. However, the ACO had devised a conversion rule that restricted the Rover to under 150 hp and assigned it to the 2-litre class.
The car was styled as a coupé with a more modern appearance than the 1963 version. In fact, it might well have resulted in a limited-series production car – a sort of early supercar – but, unfortunately, as it was larger and less aerodynamic than the 1963 model, it never managed to produce the same performance. This time Hill was partnered by the future three-time world champion Jackie Stewart, also contracted to BRM, but the British pair could fair no better than tenth. The Rover encountered no issues other than the heat, given off by the turbine, inside the cockpit but covered 357 km less than its elder sister and 700 km less than the 2-litre class-winning Porsche 904 GTS.
The hefty additional funding required to continue development cooled the ardour of Rover and BRM who subsequently shelved their “24 Hours” programme.
The next gas turbine-powered car to take on Le Mans appeared in 1968. Under the leadership of racing driver Ray Heppenstall, Howmet Corporation and Continental Aviation Engineering got together to build the Howmet TX – a coupé equipped with a 330-hp turbine entered in the 3-litre category. By way of comparison, the new Porsche 908s (one of which secured the marque’s first pole position at Le Mans) developed around 380 hp.
Again, paraffin consumption proved to be the main stumbling block although, unfortunately, the chassis also lacked rigidity. The two cars struggled for performance (20th and 24th in practice) and were eliminated by the ninth hour – one as a result of an accident and the other due to a bearing failure. Sadly, the Howmet TX prototype did not feature in the 24 Hours of Le Mans again.
The car has, however, been given a new lease of life by Ascott Collection founder Xavier Micheron. Since 2008, it has returned to the circuit for Le Mans Classic. Micheron tells the story: “The Howmet programme was more of a hobby at the time. Then one day, I scrapped that professional life and decided to dedicate myself entirely to these cars by founding Ascott and going into the trade of extraordinary cars: mainly racing cars, but extremely special road models as well. Initially, I looked for a Porsche prototype such as the 906, 907 or 910. Then I found out a chassis 2 of the Howmet was for sale in the U.S. It had been restored, but the engine was gone. One of the remarkable elements of this car is that the turbine was modified in such a way as to eliminate response time almost entirely. Another Howmet signature is the three exhaust pipes: two for the turbine and one for the evacuation of gases, which makes it possible to have almost zero response time. It was a huge challenge when I bought it because without the modifications it was practically undrivable, namely due to the response time. It took me two and a half years to track down capable people willing to restore it properly! It was a wonderful adventure…and a true consecration to bring the car to the 24 Hours of Le Mans circuit for the 2008 Le Mans Classic. The Howmet drives like an automatic, especially as it doesn't have a gearbox, but it takes adapting. The car is extremely efficient, but all prompts, whether noise or feeling, are very different from a piston engine car, if only due to the absence of a gearbox, which can serve as a prompt on a circuit. In the Howmet, I mainly use the speedometer. The Howmet TX and I have been just like old friends for 15 years. Indeed, the Howmet could provide a slogan for Ascott Collection: exceptionality through passion !”
The rotary motion, generated by a turbine on the Rover-BRM and Howmet models, reappeared at Le Mans in 1973 in the shape of the rotary engine developed by Mazda on a Sygma chassis... but that’s a tale for another day!
PHOTOS: LE MANS (SARTHE, FRANCE), CIRCUIT DES 24 HEURES – FROM TOP TO BOTTOM (© ACO ARCHIVES): Richie Ginther at the wheel of the first gas turbine-driven Rover-BRM in 1963 (#00); the second Rover-BRM that made the grid in 1965 (#31); the Howmet TX in 1968, and subsequently resurrected in the colours of Ascott Collection for Le Mans Classic.
