IMSA has enlarged the intake restrictors for both the 992 Porsche 911 GT3 R and the Lamborghini Huracán Evo2 for the upcoming Mobil 1 Twelve Hours of Sebring, the second round of the WeatherTech SportsCar Championship. Both cars suffered for lack of pace at the Rolex 24 At Daytona in January, the Porsche especially so. One Porsche team had already withdrawn from Sebring over the Balance of Performance issue, and others have said they would alter their participation in the series if something wasn’t done before Sebring.
The 911 GT3R is now allowed 38mm restrictors — the 4.0-liter flat six uses two of them. That’s an increase of 4mm from last month’s IMSA-sanctioned test at Sebring (although reports are that restrictors up to 36mm were fitted during the test), and an increase of 5mm from the Daytona specification.
According to one team running the Porsche, the 992-generation 911 GT3 R relies more on aero grip than mechanical grip compared to its predecessor, which means more drag. Sucking air through the smaller restrictors severely hurt the car’s power and thus top-end performance.
The Lamborghini moves from a single 47mm restrictor to 49mm for Sebring, an increase of 1mm from the Sebring test. That car, along with the new Ferrari 296, also was off the pace at Daytona. The Ferrari received a slight bump in boost pressure for Sebring, but also 15kg more weight, while the Acura NSX GT3 Evo22 received similar adjustments.
Other changes include an increase of the Mercedes-AMG’s minimum weight by 15kg, and 15kg reductions for the Aston Martin Vantage, BMW M4, Corvette and Lexus RC F GT3s.