A number of manufacturers have voiced support for a common Balance of Performance for GTE cars competing in both the FIA World Endurance Championship and IMSA WeatherTech SportsCar Championship.

The two series have embraced the same new-for-2016 GTE technical regulations, yet each utilize separate BoP tables, which has seen some cars with significantly different performance levels, depending on the WEC GTE-Pro class or IMSA’s GTLM category.

“Having two different BoPs for the same car facing the same competition doesn’t quite make sense to us,” Raj Nair, Ford’s executive vice president, Global Product Development and chief technical officer, told Sportscar365.

The new Ford GT — which is running both the WEC and WeatherTech Championship with identical factory programs — along with Porsche’s 2016-spec 911 RSR, are two of the cars with the most differences between the two series.

Both the Ford and Porsches are 10kg heavier in WEC trim, while the EcoBoost-powered super car has significantly less turbo boost in the WEC. The Porsche, meanwhile, runs with a 0.9 mm smaller air restrictor in the WEC.

This compares to the Ferrari 488 GTE car, which has the same 1240kg minimum weight and very similar boost levels in both series.

“At the end of the day, it’s the same cars,” Porsche Head of Motorsport Dr. Frank-Steffen Walliser told Sportscar365.

“They’re running in the same performance windows. It must be extremely close. There’s not really a reason why [the BoP] should be different.”

Both series also has full-season entries unique to their class, with the Aston Martin Vantage V8 in GTE-Pro and the IMSA-homologated BMW M6 GTLM for the WeatherTech Championship.

The Corvette C7.R, which does not run full-time in GTE-Pro, will be 10kg lighter and with a 0.2 mm smaller air restrictor once it joins the WEC field at the 24 Hours of Le Mans in June.

According to ACO Sporting Director Vincent Beaumesnil, a common set of BoP regulations is not possible due to the difference in tracks the two series compete at.

“We share all the data together but each side make their own decision,” Beaumesnil told Sportscar365.

“It’s different race tracks and there’s so many things that are different. It’s good that we can provide some information to improve the global understanding because we have more data.

“But in the end, there are so many different things, for sure it has to be independent decisions.”

IMSA President and COO Scott Atherton believes its open-book approach, along with newly mandated data logger systems on all GTLM cars, has helped all parties involved with the process, despite not utilizing the same BoP.

“The dynamics between the ACO and IMSA, especially on the technical side, is very strong and very collaborative and very supportive of each other’s goals,” Atherton told Sportscar365.

“There’s been a lot of exchange. To what extent [the ACO] have utilized the information they’ve provided… I can’t answer because I honestly don’t know. But it’s an open book.”

The first three rounds of the WeatherTech Championship have seen Corvette Racing and Porsche North America both visit victory lane, while AF Corse scored a dominant lights-to-flag class win the WEC season-opener at Silverstone last month.

Some rival manufacturers had claimed Ferrari holds a distinct advantage in the WEC, yet the car, essentially in the same configuration in IMSA, has so far only delivered a single podium finish, last time out at Long Beach.

“The BoP is a very difficult challenge for the organizers,” Ford’s Nair added. “I certainly respect what they’re trying to do. I would not want that job…

“There are aspects, looking at it from the engineering side… having the smallest displacement engine with the lowest boost curve doesn’t quite ring true with us.

“Nevertheless, we understand what the organizers are trying to do. But we’ve obviously got some concerns about the inconsistency and the overall level of where we’re at.”