Marshall Pruett photos
It's hard to miss the new diffuser on the back of Fall-Line Racing's Audi R8 Grand-Am Rolex GT car this weekend at Monterey. The ornate, unused GT3 Audi R8 Ultra diffuser is having its first run in the Rolex Series courtesy of Audi Customer Sport North America boss Brad Kettler, who had been searching for ways to provide more rear downforce to the Rolex 24 at Daytona-winning chassis.
With the required use of a smaller spec Crawford Composites rear wing, the Rolex GT R8, which was designed to work with a larger GT3-spec rear wing, has struggled to instill confidence in its Pro-Am drivers, leaving Kettler to seek other methods of settling the rear of the R8.
“We're really working hard to tailor the car to the Pro-Am drivers and their needs,” he said. “I've spent a lot of time talking with our customers to look at all the areas we can work with the Grand-Am series to make the car a lot more tailored to the drivers from inside the car – the ergonomics, the visibility, the fitment overall, and also to add more downforce.
“The car is dominant with a DTM driver behind the wheel, but the biggest area we're hurting in is the Pro-Am drivers who just aren't at the point where they can get every bit of speed out of the car. Grand-Am wouldn't let us use a bigger wing, so we looked making more downforce beneath the car with the European diffuser.”
Although the R8's GT3 rear wing won't be permitted, Kettler is confident the diffuser, which requires re-routing the exhausts to exit above the unit, will be a significant help to his non-pro customers.
“This was a proposed FIA GT3 diffuser for the R8 Ultra, which was not ratified by the FIA so it didn't make it on this year's production racecar,” he explained. “We're struggling with the extra weight distribution carried on the back of the car – it's nearly 58 percent – so downforce, however you can get it, will help settle the thing down on the rear axle. Knowing this diffuser existed, we brought it to the attention of Grand-Am, got their approval, and tested it at the Autobahn track in Illinois, and we're racing with it for the first time here in Laguna.
“Next year, the requirement (in the GT Daytona class where the R8 will race) is to have one pro and one gentleman driver, so this is the kind of stuff you need to do to make sure everyone who drivers the car is feeling confident in its handling. I think this diffuser will be a big step to get the car where we need it to be.”
Audi has seen the GT3-spec R8 become a popular, race-winning solution in the Pirelli World Challenge series this year, and Kettler hopes the changes to the car in Grand-Am trim will encourage more sales and participation when the United SportsCar Racing series debuts in January at Daytona.
“We're not claiming this will be a permanent solution, so there's more updates planned, smaller updates, but overall, we're looking first and foremost to take care of our gentleman drivers who want to race in Rolex GT,” he confirmed. “We'll continue to test this through the last race of the season in Lime Rock; it will take us at least that long to figure out how to use it to its full extent. Since this is the first time it's being used, really, we're building all that data with our friends at Fall-Line and will keep that moving into the off-season as we get ready for next year.”