WEC 2025

[AR3-GP]

Some guy did his own simulations and created a much better BOP recommendation. Ferrari and Toyota actually BOP'd properly given the data from previous races. https://github.com/andiritt/speaatools- ... BASIC/AUTO

[AR3-GP]

LMH front brake bodywork seems far more developed than LMDH cars. Peugeot, Ferrari, and Toyota are all using F1 style solutions where the wheel volume is "filled", and Ferrari and Toyota utilize heat shielding on both the inner and outer face of the brake rotor. The LMH cars use slots in the surface of the cake tin to control the amount of hot air that is reaching the wheel rim. LMDh much more simple. Porsche, BMW, and Alpine shown below. They use a single heatshield on the inboard face of the rotor and there is far less "insulation" and flow management inside the wheel.

[AR3-GP]

There are some technical differences between the brake components supplied by Brembo to the LMH and LMDh cars. LMH caliper and rotor are lighter. This makes sense because they have a larger hybrid system so they use less of the mechanical brakes.
https://www.24h-lemans.com/en/news/brem ... tems-59607

[dialtone]

Non of this is shocking though. LMH can cost $100mil or more while LMDh is supposed to cost $1-2.5mil or along those lines. There will be huge differences in complexity.

[SiLo]

Which cars are LMH and which are LMDH? Do they race against each other as part of the same category or is it an entirely separate class?

[dialtone]

Which cars are LMH and which are LMDH? Do they race against each other as part of the same category or is it an entirely separate class?

Ferrari, Toyota, Peugeot, Aston Martin are LMH.
Porsche, Cadillac, Alpine, BMW are LMDh.

They race as part of the same category, BoP is supposed to bring balance to the force, as long as they get close enough to the performance window that it can balance. All the cars are built with BoP in mind, so investing too much in a part is not going to give you returns because it will be balanced out, in theory.

Tire temperature management remains an insanely important task, and it’s difficult to BoP away, especially over 24h, so is aerodynamic efficiency.

The ruleset is much more restrictive than in f1, mandating max power, downforce to drag ratios and so on.

[vorticism]

LMH front brake bodywork seems far more developed than LMDH cars. Peugeot, Ferrari, and Toyota are all using F1 style solutions where the wheel volume is "filled", and Ferrari and Toyota utilize heat shielding on both the inner and outer face of the brake rotor. The LMH cars use slots in the surface of the cake tin to control the amount of hot air that is reaching the wheel rim. LMDh much more simple. Porsche, BMW, and Alpine shown below. They use a single heatshield on the inboard face of the rotor and there is far less "insulation" and flow management inside the wheel.

https://i.postimg.cc/RF6KrJ5Y/Image-004.png
https://i.postimg.cc/MGhXQsNs/Image-006.png
https://i.postimg.cc/6qhQFB3S/Image-007.png
https://i.postimg.cc/SR4sZnyC/Image-008.png
https://i.postimg.cc/Y2Njvz33/Image-009.png
https://i.postimg.cc/63nqLrNB/Image-005.png

Partly to do with the LMH cars having front axle drive. The CV joint is placed fully inside the wheel, which forces the brake disc farther inside the wheel (due to common upright design practices). The a-arm pivots also move further outboard to mitigate torque steer. The whole upright assembly then is farther inside the wheel, and the drum/cake-tin is used to cover it, apart from its own aero benefits. If you were to compare LMH and LMDh front wheel spokes you would probably find the LMDh wheels have a more dished appearance, and the LMH wheels to have a more flat face.

[AR3-GP]

LMH front brake bodywork seems far more developed than LMDH cars. Peugeot, Ferrari, and Toyota are all using F1 style solutions where the wheel volume is "filled", and Ferrari and Toyota utilize heat shielding on both the inner and outer face of the brake rotor. The LMH cars use slots in the surface of the cake tin to control the amount of hot air that is reaching the wheel rim. LMDh much more simple. Porsche, BMW, and Alpine shown below. They use a single heatshield on the inboard face of the rotor and there is far less "insulation" and flow management inside the wheel.

https://i.postimg.cc/RF6KrJ5Y/Image-004.png
https://i.postimg.cc/MGhXQsNs/Image-006.png
https://i.postimg.cc/6qhQFB3S/Image-007.png
https://i.postimg.cc/SR4sZnyC/Image-008.png
https://i.postimg.cc/Y2Njvz33/Image-009.png
https://i.postimg.cc/63nqLrNB/Image-005.png

Partly to do with the LMH cars having front axle drive. The CV joint is placed fully inside the wheel, which forces the brake disc farther inside the wheel (due to common upright design practices). The a-arm pivots also move further outboard to mitigate torque steer. The whole upright assembly then is farther inside the wheel, and the drum/cake-tin is used to cover it, apart from its own aero benefits. If you were to compare LMH and LMDh front wheel spokes you would probably find the LMDh wheels have a more dished appearance, and the LMH wheels to have a more flat face.

That makes sense. I did find a picture of the RWD Aston Martin LMH car which has similar design to other LMH, but no front axles/hybrid system. The others probably do it for packaging reason as you say. Aston Martin showing it's also aerodynamically beneficial. Their rim heating vents looks more deliberate as well.

[vorticism]

That makes sense. I did find a picture of the RWD Aston Martin LMH car which has similar design to other LMH, but no front axles/hybrid system. The others probably do it for packaging reason as you say. Aston Martin showing it's also aerodynamically beneficial. Their rim heating vents looks more deliberate as well.

https://preview.redd.it/spa-wec-6hr-35- ... 87e8a7a8ab

Interesting. Good posts btw. The LMDh brake discs might not be as far inboard as I assumed, looking at the LMDh pics you posted. Despite not needing to accommodate drive components, it seems they still place the upright well inside the wheel. Back to your original question then: why no cake tin. The LMDh chassis is shared isn't it? Along with the electrical drive components. If so, how universal is the chassis. Does the chassis manufacturer also supply suspension parts? The suspension items look bespoke, yet they all use a simple planar baffle instead of a full enclosure, which points to budget allowance.

The budget discrepancies seem at odds with the BoP system. How was having an expensive and a less-expensive class in the same division with ballast rules supposed to appeal to the bigger teams? Aston Martin walked before the first season started, yet came back later. BoP seems at odds with vehicle development as well. You can perfect the aero, like f.e. the Valkyrie concept, but if you get bopped what's the point?

[dialtone]

There are 4 chassis makers and everything in LMDh is off the shelf parts you buy from a few OEMs.

This was the only way to keep it alive and LMH cars will always have a very expensive advantage just because BoP is mever going to be perfect or covering everything, although it’s getting better.

Why LMH likes to be BoPed this hard I don’t know, but more manufacturers helps everyone given increased popularity.

[AR3-GP]

The FIA/ACO gives LMH their advantages back for Le Mans. No platform equivalence (LMH vs LMDh) is used. LMH cars run LMDh weights and power levels. The LMDh cars have to get lucky to stand a chance. This is the ACO's mechanism to encourage more manufacturers to join LMH if they actually want to win Le Mans. If you do LMDh, you are only granted the honor of participating.

[AR3-GP]

[JonoNic]

I'm not sure if it has been uploaded here already. Michelin's possible solution for warming up tyres quickly without tyre warmers.

https://www.dailysportscar.com/2025/06/ ... rm-up.html

[Tvetovnato]

Wow, from the timing sheets so far, and from the team comments, it seems like we could once again predict to a certainty which teams would be quickest in the coming race. How exciting.

Seriously hope they will take the opportunity to adjust this miserable BOP before the action starts for real.

[Seanspeed]

There are 4 chassis makers and everything in LMDh is off the shelf parts you buy from a few OEMs.

This was the only way to keep it alive and LMH cars will always have a very expensive advantage just because BoP is mever going to be perfect or covering everything, although it’s getting better.

Why LMH likes to be BoPed this hard I don’t know, but more manufacturers helps everyone given increased popularity.

Because if they weren't BoP'd, the whole 'sport' would be the most boring racing series in existence(even moreso than it already is), so they need to come up with an extremely artificial way to make it more exciting for fans and for inferior competitors to not completely embarrass themselves. Top teams agree to it otherwise there'd be no audience.

It's not an actual sport.