IMSA Makes Wholesale Power Adjustments for VIR

Photo: Jake Galstad/IMSA

IMSA has made wholesale power level adjustments to every GT3-spec car ahead of next weekend’s Michelin GT Challenge at Virginia International Raceway.

Released on Thursday in the sanctioning body’s Balance of Performance document, each of the nine eligible GT3 models have received power increases or decreases across the two-stage system.

Additionally, the BMW M4 GT3 EVO has received a 16 kg increase in minimum weight, with the Chevrolet Corvette Z06 GT3.R getting a 7 kg reduction.

Among the notable changes include a 4.3 percent increase in power, across both first and second stages, for the Ford Mustang GT3, a 4.5 percent increase in Stage 1 power for the Lexus RC F GT3, and a 5.6 percent increase in Stage 2 power for the Lamborghini Huracan GT3 EVO2.

The single-biggest change is with the BMW, which gets a 7.6 percent increase in second-stage power.

While the majority of the cars have received power increases, both the Lamborghini (-0.5 percent) and Mercedes-AMG GT3 Evo (-0.9 percent) have received slight power cuts at Stage 1, while reductions have been made at the second stage to the Corvette (-1 percent), all when compared to the last race at Road America.

The threshold between first and second stages remain at 190 km/h and 200 km/h, respectively.

“The goal of IMSA’s Balance of Performance process for GTD and GTD Pro is to maintain performance parity between the fastest GT3 entries across all circuits and race lengths,” a statement from the IMSA technical committee read.

“The unique variety in GT3 machinery—from aerodynamics and bodywork to engine design and placement—produces performance differences that vary from track to track, so the IMSA Technical Committee’s BoP process has been constructed to adjust for these influences by leveraging a common set of tools including torque sensors, wind tunnel data, and simulations.

“Encapsulated in the BoP process are structured calculations that adjust for trends in demonstrated performance over the most recent events.

“However, the track-to-track influences are significant for GT3 cars and tend to account for the majority of adjustments listed in IMSA’s BoP tables.

“IMSA continues to engage on all BoP matters with IMSA’s manufacturer partners in regularly scheduled open forum discussions.

“These meetings continue to provide our manufacturers with the opportunity to critique the process and provide additional feedback, all of which helps develop and improve the BoP processes.

“This in turn helps to keep our joint customers informed, ensuring IMSA’s administration of the process is transparent.”

John Dagys

John Dagys is the founder and Editor-in-Chief of Sportscar365. Dagys spent eight years as a motorsports correspondent for FOXSports.com and SPEED Channel and has contributed to numerous other motorsports publications worldwide. Contact John