IMSA Introduces New Balance of Performance Process in GTLM, GTD Classes


IMSA Introduces New Balance of Performance Process in GTLM, GTD Classes
Photo Credit: Jan Magnussen/Twitter

Mention IMSA and Balance of Performance testing and most Corvette Racing enthusiasts roll their eyes while muttering about how arbitrary and unfair the process has been to our C7.Rs. That’s because the previous BoP calculations only took into account timing and scoring data. But for 2016, the process has changed significantly thanks to a new system of individual data loggers which are mandatory on all GTLM and GTD cars.

These new data logger systems now capture a race car’s RPMs, throttle position and airbox pressure to give IMSA officials a much better look at what the car is doing. In other words…no more sandbagging as officials will be able to see if a car is being driven as it should or if its being held in check by the driver.

Another scope of IMSA’s Balance of Performance system is “instant spot-checks” at the track. Officials can order “spot checks” during the practice sessions which brings a race car directly to the IMSA scrutineering bay to verify the configurations such as wing angles, weight and ride height.

Corvette Racing’s Doug Fehan, no stranger to speaking out about the inequities of previous BoP changes, told John Dagny’s that IMSA has recognized “that they can do better… and they have”.

“When you recognize where your soft spots are, that’s the first step in getting them fixed. We’ve got that recognition from them and their expressed willingness to improve,” said Fehan.

The new data loggers aren’t cheap. Each car in GTLM and GTD requires the new tech at a cost of $18,000 each. The systems by Bosch also mirror the FIA’s new Balance of Performance system so cars that race in the 24 Hours of Le Mans will also be using a similar process.

During the off-season, IMSA also conducted wind tunnel testing to determine the aerodynamic characteristics of each car.

“We had a great Windshear wind tunnel test with all the manufacturers,” Fehan said. “It was a very, very, very productive test. It’s the starting point.”

“Balance of Performance will never be perfect but we know it can be a lot better,” Fehan added.

The first real test with the new Balance of Performance system will come this weekend at the 54th Rolex 24 at Daytona. While no system appears to be perfect, we are glad to see IMSA moving in the right direction. Read the full article at

As for the current BoP for the Rolex 24 at Daytona, Corvette Racing’s C7.Rs had their air restrictors changed and now have smaller holes to feed air to its 5.5L V8 engines. The Corvettes lost a total of 0.4 mm from the twin restrictors which now have openings of 29.9 mm. The BoP tables also show the Corvette’s fuel capacity at +6 liters for a total of 92L.


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  1. Listen Vette fan boy….the Vette does get 92 liters of fuel capacity….but the Ferrari 488’s get a measly 79 and are made to run the smallest intake restrictor of ALL other GTLM cars as well as having to run the smallest refueling nozzle of all that slows refueling during pit stops….yea, real equal…the Vette wins at Daytona and Sebring are hollow wins….just get that damned Vette to LeMans under WEC rules that are more equal and we will see who beats who….IMSA BoP is the worst….totally unfair to the far superior 488, as usual, the Ferrari gets penalized for being a far more efficient car….I guess it’s cheaper to tell IMSA to change the rules rather than have the Vettes raise their game huh?…

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