As drivers and teams begin to descend upon the historic Sebring International Raceway for the 62nd Annual Mobil 1 Twelve Hours of Sebring, which takes place on Saturday, March 15th, final “Balance of Performance” changes have been released in order to decrease the competitive gap between the classes. Unlike previous “Balance of Performance” changes, this final round only sees three classes, Prototype, GT Le Mans and GT Daytona being affected.
In the Prototype class, the Corvette DPs, which posted the fastest lap time in recent testing at the 3.7-mile Sebring circuit, see a pair of smaller 33.8mm restrictors aimed at reducing power in addition to a Rev limit of 7,450rpm being established. The3.5-liter twin-turbo V6 Ford EcoBoost-powered DPs sees a slight increase in restrictor size of 33.7mm, in an effort to match the naturally-aspirated Chevys. Honda’s 3.5-liter twin-turbo V6 DP engine, which are set to compete for the first time at Sebring, have had their restrictors established at 33.7mm, turbo boost for the P2-derived engine has been set slightly higher than that of the Fords at 26.7 psi. The biggest restrictor changes were seen on the Dinan-prepared 5.0-liter BMW V8 which saw its pair of 76.4 mm restrictors reduced to 72.9 in an effort to bring its performance in line with the other DP motors.
GT Le Mans saw fuel capacity reductions following Daytona, in order to shorten driving stint lengths for all cars in the class. Additional tweaks have been made following recent testing at Sebring. Porsche’s 911 RSR see a reduction from 110 liters to 99, Corvette’s C7.R have been reduced from 110 to 96, Ferrari’s F458 see a decrease from 110 to 94, and SRT’s Viper see the largest reduction from 120 to 103. In addition to fuel capacities, the V8 Vantage received a significant 30-kilo weight break from the test, reducing the Aston from 1205 kg/2657 lb to 1175 kg/2590 lb. The BMW’s Z4s have been given clearance to use modified door sills in addition to being given an extra 10mm Gurney for its rear wing.
Like the GT Le Mans class, GT Daytona saw large fuel capacity reductions following Daytona. However, IMSA has now reversed these changes adding back much of the capacity initially taken away, in some cases allowing more fuel capacity than at Daytona. Porsche and BMW see reductions in capacity as the Porsche’s 911 GT America will race with an 83-liter tank, down from 85 while the BMW z4s see a reduction from 100 to 89 liters. Ferrari, Audi, Aston Martin and the SRT Vipers see increases in fuel capacity from previous reductions as Ferrari’s F458 are increased from 86 to 92, Audi’s R8 jump to 94, up from 86, Aston Martin’s V12 Vantage will have 97, up from 90, and SRT’s Viper will have 104, up from 95. Additional body work adjustments have been made to the Porsche’s GT America’s with an allowance to use Crawford’s spec DP rear wing. IMSA announced Saturday additional specifications of the GTD wing and endplate heights following controversy, in order to standardize downforce and drag. “In the complete operating range, the complete wing and end plates must measure at a maximum equal to roof height and at a minimum -60mm below the roof height and 101.5mm maximum, 77mm minimum rearward of the rear most perimeter of the body work when viewed from above. The operating range for the rear main plane angle as indicated by the manufacturer will be specified in the Adjustment of Performance Bulletin.”
Stay up-to-date with TUSCC news as OpenPaddock’s prepares to provide coverage of the 62nd Annual Mobil 1 Twelve Hours of Sebring. The event will be broadcast live on Fox Sports 1 at 10am EST with coverage moving to IMSA.com at 1pm EST.
Poster designed by Roger Warrick
