GRAND AM GT
The Ferrari 458 features a rollcage that is more robust than that required by the FIA, and so is suitable for both markets with only limited adaptation
levels around 450-500bhp, so that meant some reductions were needed. We looked at the Ferrari, figured out that the gap between torque and power was a little too big – it’s a high revving engine [8000rpm] so it makes good power but, at 4.5-litres, it doesn’t make a lot of torque. So we came up with a specification that they agreed was sensible and that’s what they built. When they brought it to the dyno it was spot on.’
With the F458 so new to
the world of racing, Grand-Am has given Ferrari teams options for its Rolex GT racer that, to date, have not been afforded to the battle-tested R8 LMS. Raffauf: ‘We’ve given Ferrari some freedom, particularly with the springs and gear ratios and things like that. In GT3, you pretty much use the ratios and the springs you want, or are needed, on a variety of tracks. We only give them the option of two homologated sets of gear ratios and springs. That’s pretty much it.’
ADD, THEN SUBTRACT With all of the aforementioned additions to Grand-Am’s new GT3-spec cars, the greatest changes to the platform are to be
found with the subtractions that were required for it to compete in Rolex GT competition. ‘Our new GT3 manufacturers
took out all the street driver aids. Those are part of the European GT3 spec, but our GT cars don’t use them. There’s no traction control, no ABS, none of that stuff. The systems designed for the street don’t really work on the racetrack. And the cost of doing racing versions of some of that stuff… it’s too stupid, even for GT3. Some of them have
be required to make the same modifications. Tasked with the same build
requirements as Michelotto, Romolo Liebchen, Audi’s head of Customer Sport, had the benefit of starting with the proven, championship-winning R8 LMS to transform into what it calls the ‘R8 Grand-Am’. ‘From outside, we did what
we thought was reasonable. We had to change the aerodynamic components like the splitter, the diffuser and the rear wing. The
“We had to change the
aerodynamic components like the splitter, the diffuser and the rear wing”
production systems in there but they’re not as effective as they could be.’
Although many GT3 manufacturers would undoubtedly debate Raffauf’s opinion on how suitable those electronic systems work in the Euro versions of both models, Grand-Am’s firm stance on the topic means that current and future GT3 marques will all
22
www.racecar-engineering.com • February 2012
rest of the body is from what we already have. The diffuser was modified to reach the shape, which is now quite similar to the road car shape. The splitter was then modified to work with the new diffuser, which has less diffusion than the [standard] GT3 version.’ However, not wanting to miss an opportunity, Audi went to great lengths to make sure the
Grand-Am version of the R8 could also be quickly converted to race in other championships. ‘In principle, everything can be changed back, with the only exception being the rollcage. We had to modify some tubes from 1.5mm up to 2mm, so we have now a special rollcage for Grand-Am and generally, while no European GT3 car can come to Grand-Am without the changes, the R8 Grand-Am can go the other way around. ‘We made things quite simple
in other ways too, so we stayed with ABS and kept the electronic unit in the car, only modifying the housing for the brake system so no brake lines go to the ABS module, but instead go directly to the caliper. So, in principle, it’s quite easy to make the change back to working ABS in the car. Same with traction control. This was the reason we had to remove the rear wheel speed sensors, but those are very easy to put back.’ Surprisingly, despite lacking
the assistance ABS provided the GT3 version of the car, Audi was able to retain the same brake package from the R8 LMS. Although Grand-Am does not
traditionally publish the restrictor sizes it mandates for each model, Audi, like Ferrari, will have a few
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