Yes, There Are Differences Between WEC Hypercar and IMSA GTP LMDh

Yahoo

19-02-2025

What are the differences between these very similar sports car prototype categories?
How close are they when it comes to equating them by Balance of Performance (BoP)
Here's a brief summary of the significant comparisons that distinguish each class.
Common sense has finally prevailed in sports car endurance racing after three decades of bickering over the rules.
An historic convergence of rules used for the World Endurance Championship's Hypercars and IMSA's LMDh category has attracted an unprecedented variety of manufacturers.
Although the WEC teams have yet to fully embrace competing in IMSA, since 2023 fans have warmed to the new era of the predominantly hybrid classes. The turnouts at the Rolex 24 at Daytona and the race's electronic media ratings have pushed the envelope. The same has been true at the 24 Hours of Le Mans.
But what are the differences between these very similar categories? How close are they when it comes to equating them by Balance of Performance (BoP)? Here's a brief summary of the significant comparisons that distinguish each class.
The Hypercar prototypes, also known as the LMH class, are built from the ground up by a manufacturer according to the overall dimensions in the WEC rulebook.
In LMDh, which is designated as the GTP class by IMSA, there are four approved suppliers of standard chassis—Dallara, Ligier Automotive, Multimatic and Oreca.
Hypercars can be powered by a hybrid system, but a manufacturer can rely solely on a turbocharged or normally aspirated engine.
The LMDh cars are all hybrids with ICE power plants. With cost containment in mind, they carry the same KERS components of a Bosch-built MGU, a battery manufactured by Williams Advanced Engineering and an Xtrac gearbox.
The Hypercar hybrids of Ferrari, Toyota and Peugeot are all-wheel-drive with the KERS installed at the front axle, as required.
LMDh cars have KERS installed at the rear axle and are rear-wheel drive.
Manufacturers in both classes have a limited opportunity to create bodywork with their company's design cues. But the bodies must conform to a performance window and a downforce-to-drag ratio of 4/1.
Hypercars are allowed one adjustable aerodynamic device and are tested for homologation in the Sauber wind tunnel in Switzerland.
The LMDh cars are tested for homologation at the WindShear tunnel in Concord, N.C., which yields slightly different and more detailed results than the Sauber tunnel.
Freedom of engine choice is one of the appeals of Hypercar and LMDh. The rules call for total energy per car with a traditional ICE being regulated on its power output for the sake of competitive balance.
Hypercar engines include V6 twin turbos found in the Ferrari, Peugeot and Toyota. The Alpine employs a single turbo V6. Aston Martin uses a normally aspirated V12. The original benchmark before BoP adjustments was 670 horsepower (500 kW). The new 'Power Gain' adjustment above a benchmark speed at each track was introduced at Le Mans in 2024.
LMDh engines include V8 twin turbos in the BMW, Lamborghini and Porsche entries, an atmospheric V8 at Cadillac and a V6 twin turbo in Acura's entry. Coming into the current season, the Cadillacs were allowed 500 kW and the other manufacturers were limited to 520 kW. All competitors also have their power adjusted by Power Gain.
Both classes have a minimum weight of 1,030 kilos (2,270 pounds) before BoP comes into play. That's relatively heavy compared to preceding prototypes, which shows in the slower lap times. But it accounts for the weight of the KERS and leaves room for BoP adjustments.
Each sanctioning body does its own homologation and BoP, which is primarily based on adjustments to kW power and weight. The eternal debate continues about BoP's influence on competition.
Hypercar and GTP teams are allowed five 'joker EVO' adjustments over the course of the class, which has been extended through 2029. But the changes to homologation must be made for reliability and not improved performance, given that BoP attempts to keep competition equal. What constitutes a 'joker' is negotiable with the sanctioning body.
Hypercar teams have been allowed to introduce 'jokers' at any point in the WEC season, albeit two races prior to the Le Mans 24-hour.
GTP participants have a gentlemen's agreement with IMSA to limit 'joker' developments to between seasons, which makes the task of homologation less difficult for teams and the sanctioning body.
In the first two seasons, the exchange between the two series was only one-way with four of the five manufacturers building LMDh entries choosing to compete in the WEC and IMSA—BMW, Cadillac, Lamborghini and Porsche. (The Alpine entry in the WEC is also an LMDh.) The new Valkyrie ASM-LMH of Aston Martin is the first Hypercar to compete in IMSA as well as the WEC.
Victories in the WEC by Porsche Penske Motorsport in Qatar and the privateer Porsche 963 of Jota at Spa in 2024 have confirmed the LMDh cars can beat the LMH cars. Le Mans is annually the ultimate test of whether the BoP system creates a level playing field—and whether the bad old days of bickering are truly gone.