It was never going to be simple. Audi’s Motorsport boss Wolfgang Ullrich was scathing when, later in the year, the car ran around Silverstone belching black smoke. He felt it was damaging the image of the diesel. What he was conveniently ignoring was that Dawson had to carry out his development in public with a budget the size of the change in an Audi executive’s back pocket.
The experienced Dawson had been a Team Lotus mechanic in the 1970s and had subsequently turned sportscar entrant. He was already running a pair of silver Lola B2K/10s under the Team Taurus banner when it was decided to replace the conventional engine in one of them. With Le Mans regulations allowing greater restrictor area and boost pressure for compression ignition engines, his team removed a 5.0-litre V10 TDI unit from a Touareg, liaised with engine tuner Mountune (which had already carried out design studies on racing diesels) and married it to one of the Lolas. Perkins, the world largest manufacturer of diesel engines, agreed to provide technical support in return for the badging rights to the engine. “We wanted a diesel partner to cast its eyes over what we were doing,” recalled Dawson. “Electronically and fuel management-wise the engine was all Caterpillar controlled.” The Touareg’s Bosch ECU was rights protected and so Pectel hardware was used enabling Caterpillar to code the engine management strategies. It additionally advised that the original pistons had the dome in the centre of the combustion chamber machined to reduce the compression ratio. Working with Caterpillar also meant a closer relationship with Garrett who supplied the twin turbocharger. The conversion was carried out in time for the 2004 Le Mans race. However, the demands placed on the clutch were to cause difficulties and it retired just short of three hours from the start.
During preparation, severe torque spikes were experienced when flat-shifting through the gearbox. Following a clutch problem the engine was also re-mapped to a lower power figure, nearer to 400bhp than the 520bhp seen earlier. This resulted in an improvement in throttle response and in getting the car out of the slower corners. However, it also increased stress on the clutch. Had the car been able to use a carbon clutch – with a theoretical torque capacity of a whopping 959lb ft (1,300Nm) – as originally envisaged, Dawson felt that it could have run for much longer. However, the team’s only such clutch failed during practice and was replaced with a lower torque capacity sintered version. A selector fork also broke during warm-up to the race. Driver Phil Andrews started from the pit lane as a safety measure, but the knock-on effect was to prove the team’s undoing.
Andrew’s team mate, Calum Lockie observed that the main difference between the diesel and other cars he raced was the noise… or lack of it. “The diesel was so quiet you had a different appreciation of what was happening. By far the loudest thing was the wind noise rattling your visor.” For Lockie, unable to identify by engine sound when he needed to change gear, it was like driving an aeroplane, relying on instruments rather than senses. There were other differences for the driver, one being the considerably narrower power band. “We had from 3,300 to 4,500rpm to use and that was it.” That meant the engine was revving quickly through the low gears with little time between gear changes. “You really had to concentrate to avoid hitting the rev limiter.”
There was also the “hefty” weight of the engine. This, in combination with the huge torque, the Lola’s short tail and a relatively rudimentary rear wing meant that the drivers had to be careful with the throttle coming out of the slow corners. As the weight came off the wheels, the car could snap away into oversteer or spin with no warning. There was also that black smoke when the drivers came off and on the throttle. Dawson pointed out that the team was running with normal diesel fuel without additives. Whatever Dow Automotive could do for Audi and Peugeot, it was unlikely to develop a diesel particulate filter for his little, Norfolk-based team.
After the race, Dawson spoke of a plan, money permitting, to convert the car to comply with the then new LMP1 specifications, enabling the team to replace the car’s 80-litre tank with a 90-litre version. In 2004 it had managed 16 laps without a pit stop; Dawson believed it could have gone 17. That year the conventional Audi R8s were doing 11. “If we could run for 20 laps with sub four-minute times then we could make sense of what diesels can do.”
The car also ran at Silverstone getting into the top 20 before a rear end oil leak caused its demise. However, come the end of the season Team Taurus just did not have the funds to continue. A sponsorship broker appeared with what turned out to be a dubious and ill-conceived plan from which Dawson painfully had to extricate himself. Money from D1 Oils did, though, mean that the car could be converted to run on biodiesel (based on jatropha berry) and further testing was carried out.
By this time, his Lola chassis was obsolete but you cannot keep Dawson down. The American Le Mans Series was actively promoting “cleaner” racing and he turned to the USA. The engine, now tuned by AER, was installed into a newer Radical SR9, which turned up at the 2008 12 hours of Sebring but did not start having failed technical inspection because of a number of small problems. Eventually, the car ran at Laguna Seca. By 2010 Dawson had abandoned his Touareg power unit and the Radical was fitted with a petrol engine. He remains proud, though, that he was the first to use a diesel engine in modern endurance racing.