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Technical Details Confirmed for LMH, LMDh Convergence

FIA, ACO, IMSA outline four key areas of LMH, LMDh technical convergence…

Image: Porsche

The FIA, ACO and IMSA have confirmed the four key areas that will allow convergence between Le Mans Hypercars and LMDh machinery beginning with the 2023 World Endurance Championship and WeatherTech SportsCar Championship seasons.

Revealed following the FIA World Motor Sport Council’s approval of the “technical regulation amendments” on Thursday, a joint press release issued on Friday has also confirmed LMH’s eligibility in the WeatherTech Championship starting in 2023.

The key areas between the two platforms are tire fitment, acceleration profile, braking capability and aerodynamics, with LMDh cars largely adopting the rear-wheel drive technical profile outlined in the current LMH regulations. 

LMDh cars will use the LMH tire size regulations for RWD cars, allowing for 34-inch tires in the rear and 29-inch tires in the front. 

This compares to the 31-inch tires (front/rear) currently used on LMH cars equipped with a front axle hybrid, such as the Toyota GR010 Hybrid and will remain unchanged heading into 2023.

The acceleration profile for AWD cars, however, will now be controlled through Balance of Performance instead of being part of the technical regulations, with two BoP activation speeds (dry/wet) to be utilized at each circuit, likely between 120-160 km/h.

This method, which will be adjusted by the characteristics of each circuit, has already been tested in the most recent WEC race in Portimao, when the Toyota had an adjusted acceleration profile for its front drivetrain.

LMDh cars will have control software to limit the contribution of its rear-axle mounted electric motor for traction control capabilities, meanwhile.

Both types of powertrains will have identical coasting capabilities, with AWD cars taking into account both the front and rear axle torque levels.

Additionally, the front differential on AWD cars will now have a zero-lock mechanism activated on coasting in an effort to prevent any potential performance advantage.

In the aero department, LMH cars will continue to be homologated at the Sauber wind tunnel in Switzerland, while LMDh cars will undergo homologation at Windshear in North Carolina.

However, LMH cars taking part in the WeatherTech Championship and LMDh in the WEC must undergo “wind tunnel characterization” tests at each other’s designated facilities.

“This major announcement stems from our ambition to forge a common future for endurance racing,” said ACO President Pierre Fillon.

“We have all worked together to achieve this landmark agreement and I would like to thank all the stakeholders very sincerely.

“It is wonderful news for teams and fans alike and maps out a bright future for endurance.

“The manufacturers dreamed of being able to participate in the greatest endurance races in the world with the same model of a car: this will now be reality.”

IMSA President John Doonan believes that the group meeting last month in Paris, which led to Friday’s formal announcement, has the potential to “revolutionize” prototype sports car racing.

“The stage is set for a highly competitive top category that will include many of the world’s greatest automotive manufacturers, showcasing relevant technology in the world’s most prestigious endurance races,” he said.

“Collectively, we have an opportunity to engage with the next generation of endurance sports car racing fans and elevate our sport to the highest levels.

“I cannot be prouder of the spirit of collaboration between our IMSA team, our colleagues at the ACO and FIA, and all of our automotive partners.”

FIA Endurance Commission President Richard Mille added: “The principles have been agreed by all parties.

“The dream of teams and manufacturers being able to compete in all of the top endurance races with the same car for the first time is now at hand.

“This represents a significant moment in the history of motor racing.”

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

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