Diesel Performance-Balancing Starts Now
An IMSA bulletin released yesterday, July 13, reveals that from now on, the Audi R10s will have to be refuelled using the same 33 mm diameter refueling hose as the petrol-powered cars – rather than the 38 mm hose used at Sebring and Le Mans.

“As was highlighted in today’s press bulletin issued by the ACO, there is an overall desire by the organizing bodies to work toward a situation where all cars, no matter what fuel they choose to use, have the same amount of energy on board,” said Tim Mayer, Chief Operating Officer of IMSA. “However, that is not the situation with the current regulations. So as an interim step, we have restricted the R10 so that it cannot receive more energy in the tank in a given time frame.

“We notified the team of this change at the Lime Rock Park event. However, because of a variety of test and calculation methods that are possible to determine the energy content of fuels, we chose to hold the public release of the bulletin until we had verification of the numbers.”

“The original intent was to permit the full volume of the tanks to be filled in the same time,” said Mayer. “However, diesel is a more energy-rich fuel for any given volume. The change that we have implemented means that the energy delivered will be similar, for the diesel versus gasoline, for the same length of refueling. The goal is to ensure that competitors have the opportunity to compete without a quirk in the physics of the fuels creating a particular advantage. We are currently working with the ACO to come up with a formula for tank sizes for a variety of different fuels.”

Here's Allan McNish in action at the new Utah track on Thursday evening: the Audis were third and fourth fastest, behind the two LMP2 Porsches - which have tested at the track already.