While we were over at Goodwood Festival of speed, we had the chance to check out the winner of the 2003 Le Mans 24 hour race and get some insight into a few of the technical aspects of the car. After getting back into things in 2001, this was the first Team Bentley car to win at Le Mans since Woolf Barnato, Glen Kidstonthe and their Bentley Speed 6 won the 1930 event.
The X-Trac sequential fitted 600HP Bentley 4 litre 90-degree V8 engine was originally based off the Audi R8's 3.6 V8 and is direct-injected which, while common nowadays, was a relatively new technology back in 2003. This was done to achieve greater fuel economy and allowed the car to complete one more lap before needing to be refuelled. While this may not sound like much, when you consider that the car could only complete about 14 laps before needing to be refuelled, any gain in fuel economy is a huge advantage.
These cars were restricted to maintain power parity which was achieved in two ways. Two 34 millimetre restrictors were installed on the inlet to the turbocharger to restrict the airflow and limit the amount of power the engine could produce. The boost was also restricted to run up to 1.8 bar (26 psi) of absolute pressure, or 0.8 bar of positive boost pressure above atmospheric.
Designed, developed and built by Racing Technology Norfolk, the team achieved boost control within 0.01 bar by using an onboard compressor which feeds air from a pressurised reservoir up to the top of the wastegate and the specific 1.79 bar pressure was maintained by the ECU instead of the more common approach of directly controlling boost pressure in the inlet manifold. For those who work in imperial, that's accurate boost control from the Garrett turbos within 0.15 psi.
Since the car was somewhat ahead of its time running direct injection, it may surprise you to know that it still ran a cable throttle body system. As the car uses dual plenums with dual throttle bodies, connecting the driver's throttle pedal up to the dual throttles was complex. The throttle pedal is attached to a central bell crank mounted at the rear of the engine which feeds off to the two throttle bodies, allowing them to be actuated and matched to each other.
This car has an impressive aero package fitted to it. The car weighs a mere 900kg yet at 240kph, the car produces an insane 2200kg of downforce. Knowing this, you can only imagine the kind of downforce that is produced at the car's alleged top speed of 341kph.
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