A racing car is hardly environmentally friendly. Yet a team based in Kent, England set out to prove otherwise at this year's Le Mans 24-hours and, having run for around three quarters of the race before retiring, can be said to have proved its point. Ian Wagstaff was there.

A magnificent effort to bring the benefits of bio-ethanol fuel to a wider audience ended when a specially converted Reynard 01Q sports-racing car, driven by Romain Dumas, Werner Lupberger and Robbie Stirling, blew its engine having completed 139 laps. Had it run the full distance it still would have required only an acre and a half of corn to produce its fuel.

Bio-ethanol is alcohol distilled from, in this case, corn mash. Virtually all of the CO2 (carbon dioxide) that is released when the alcohol is burned is reabsorbed by the next crop.

Team Nasamax, which ran the Le Mans car is a consortium of parties interested in both motor sport and alternative energy. Included are 02 Empower and ASTEK, which specialises in technology for the manufacture of bio-ethanol and, importantly, ways to make production more economic.

The team was only given the go-ahead to enter a bio-ethanol fuelled car in the race in December. The rapid development programme, combined with an engine that destroyed itself in the morning warm-up session leading to a four hour engine change and other consequential damage that led to such as gear selector problems, meant that completing over 16 hours of the race was a major achievement. For eight of those hours the team reported that it ran "with no problems at all." Records could be claimed as this was the first time that wholly renewable fuel had been used at Le Mans. (Interestingly, the race organisers, the Automobile Club de l'Ouest (ACO), have announced that diesel fuelled cars will be permissible next year. Ricardo has already designed a 600bhp, 1400Nm, 5.5-litre all-aluminium V10 diesel racing engine which will be entered if backing can be found.)

Competitive lap times - the Nasamax car was 21st out of the 49 cars that practiced - were achieved but the volumetric efficiency of the fuel compared to gasoline meant more pit stops (one more every two and a half to three hours). Bio-ethanol has about 60% of the calorific value of gasoline and therefore a greater volume needs to be burnt. Race regulations stated that the car had to have the same sized, 90-litre fuel tank as the others in the LMP900 class. Next year it is expected that the race organisers will rewrite the rules to give bio-ethanol fuelled cars parity. For 2003 the team's position right at the far end of the pit lane gave them easy access to their fuel.

Cosworth Racing developed the car's 2.65-litre V8 turbocharged engine from its successful methanol-burning XD used in the mainly North American based Champ Car single seater series According to the company's Performance Engineering Group Director Bruce Wood, much of the work converting what had been an engine used to 400-mile rebuilds concerned running it to the 45mm restrictor sports car specification and the vastly increased longevity required.

"We had to change to a twin compression ring piston to give it enough compression over 24 hours, thicker crown and bigger section for the connecting rods," recalls Wood.

Traditionally pistons for the XD, in Champ Car specification, would be thrown away every 400 miles and rods every 800 miles. This year's winning Bentley at Le Mans covered 3,196 miles during the 24 hours; a very different tale from the Champ Car race (in which all the cars used Cosworth engines) held in California the same weekend that lasted but 195 miles.

"In some respects, converting it to run on ethanol was less of a big deal than converting it to run to a restrictor sports car specification," says Wood. "The engine was designed as an unlimited engine only limited by boost. The engine in Champ Car days used to run at 15,300 rpm on a very low boost. To run it to sports car regulations there had to be a restrictor, which went into choke at about 8-9,000 rpm. The design of the engine in terms of ports trumpets, exhausts and cam timing were all designed for a very high speed, low boost. Now what we were running is a relatively low speed, high boost engine.

"We also turned our attention to running a wider power band, which meant increasing the boost at low speeds using different cams and a longer exhaust system."

To cope with the different fuel, modifications had to be made to the fuel system and inlet air system to ensure complete and efficient combustion. An alternative exhaust system and changes to the housing and vanes of the Garrett turbo-charger had also to be made. The engine had run in Champ Car form with a single turbo and, because of the lack of development time, it was decided to leave that configuration as it was.

However, changes were "mostly to do with re-mapping and how the fuels works," according to Team Nasamax technical consultant John McNeil who heads up Sittingbourne Analytical Laboratories, a specialist in alternative fuels.

Some of the changes were driven by the ACO. The club would not allow the team to run with the pre-compressor ignition used in the Champ Car engine that enables 50% of the fuel to be put in before the turbocharger, thus giving it a longer period to vaporise. "We had to change our injection philosophy," says Wood. Ethanol runs a different stoichiometric to methanol and an alternative spray cone had to be use to vaporise it.

The installation was found to be very temperature sensitive, the higher temperature bringing the density down. Boost response was also lost in high humidity, an added problem when the car made its debut earlier in the year at Sebring, Florida. Bio-ethanol also has a higher ignition point meaning different temperature range Bosch spark plugs were used from that found in the original Champ Car engine. Even these were changed during the race after too rich fuel had been found in the exhausts. Valve seat regression was also found to be a problem during development.

Bio-ethanol has to be purchased as a fuel to avoid alcohol tax. That means it has to be 'de-natured' with 5% of additives. "We found about 20 hp difference from one fuel to the next, depending upon what it was doped with," says Wood. The mix used at Le Mans included 3% acetone and 1% isopropylalcohol as well as around 20 parts per million Bitterex to give it an unpalatable taste.

One perhaps less obvious environmentally friendly result is that this car sounds quieter than its competitors. The team is also at pains to point out that it also smells a lot better!

Perhaps the nearest that Le Man has seen to this entry was the Rover-BRM gas turbine cars that ran in the mid-1960s. However, running a bio-ethanol fuelled car was, for Team Nasamax, not so much a case of proving that the technology works but more of raising the profile of 'renewable' fuels. With the cost of fuels cells still proving prohibitive, it is becoming increasingly important to give such avenues greater exposure. Team Nasamax is to continue its programme and has already entered the six-hour race due to take place in November on the short Le Mans-Bugatti circuit.

Auto market intelligence
from just-auto

• Auto component fitment forecasts
• OEM & tier 1 profiles & factory finder
• Analysis of 30+ auto technologies & more