McLaren MCL39

[Andi76]

A material weighing 3 to 4 kg that turns into a gaseous state at 5 degrees Celsius is supposed to keep four tires and brakes within the window for an entire race?

this is pure speculation

let's assume they are cooling only rear wheels

it' 3-4 litres, dry ice density is about 1,5 so it's 4,5-6kg

6 kg of dry ice generates 3300 litres of CO2.

for a 90 minutes race it's 18,3 litres/minute (or 0,3 l/sec) of 5C CO2 for each wheel

again, this is pure speculation but nobody add 4,5-6kg of weight on a F1 car just too cool the drivers (and the mandatory cooling equipment by FIA is totally different)

Most cars in 2025 will be 5 to 10 kg below the minimum weight. In 2023, the Alpine was already 8 kg below the weight limit. Placing 5 kg in the center of the front axle should therefore not be a problem, and ballast so far forward would not be unusual. In 2006, Ferrari had ballast right at the front of the nose... Of course, there were no regulations regarding weight distribution at that time, but the current regulations allow for a margin of approximately 12 kg. Even additional weight to cool the driver would not matter in the case of an official heat race, as the weight limit is raised in such cases.

Your calculation is very nice, but how would the gas reach the rear tires? There would have to be a direct connection. And above all, would something that sublimes at -78,5 degrees be used for cooling something that gets +100 to 140 degrees hot (basket + tires)? 5 kg of dry ice "melts" outdoors at 30 degrees in about half an hour. Sure, the container would be well insulated, so it would last much longer, but considering the energy and temperatures generated by an F1 car when braking... an F1 car generates 2.8 MW of energy every time it brakes, enough to power a small town for 14 hours. So the forces, energy, and heat are enormous. And a little dry ice with a direct connection... and you also have to keep in mind the mass to cool. I find it hard to imagine that this would survive for any length of time, also it would be a very ineffective cooling system, especially since it would be difficult to "adjust". The latter is almost the bigger problem for me, because you would have to calculate the exact amount of gas and adjust it to keep everything "within the window" permanently. That would be very difficult, more difficult than "durability." Because ultimately, when you think about it, we're talking about a few degrees that this system actually has to cool down, since the brake ventilation should already keep the tires close to the window. So if you've managed to develop a system that only transfers in one direction...
The "cold spots" could indicate that gas is flowing in there... SPECULATION, I would like to emphasize again. But be that as it may, it would not be very efficient, very difficult to "adjust," especially permanently consistent.

Much more effective and efficient would be a material that melts at 140 degrees and absorbs the heat up to that point. But anyway, it's all speculation. I find it hard to imagine. What is clear to me is that McLaren has definitely done something with the brakes. The burning brakes and the problems they had clearly indicate this. However, I am NOT saying that this is one of the systems that has been and continues to be the subject of so much speculation.

[mwillems]

A material weighing 3 to 4 kg that turns into a gaseous state at 5 degrees Celsius is supposed to keep four tires and brakes within the window for an entire race?

this is pure speculation

let's assume they are cooling only rear wheels

it' 3-4 litres, dry ice density is about 1,5 so it's 4,5-6kg

6 kg of dry ice generates 3300 litres of CO2.

for a 90 minutes race it's 18,3 litres/minute (or 0,3 l/sec) of 5C CO2 for each wheel

again, this is pure speculation but nobody add 4,5-6kg of weight on a F1 car just too cool the drivers (and the mandatory cooling equipment by FIA is totally different)

Most cars in 2025 will be 5 to 10 kg below the minimum weight. In 2023, the Alpine was already 8 kg below the weight limit. Placing 5 kg in the center of the front axle should therefore not be a problem, and ballast so far forward would not be unusual. In 2006, Ferrari had ballast right at the front of the nose... Of course, there were no regulations regarding weight distribution at that time, but the current regulations allow for a margin of approximately 12 kg. Even additional weight to cool the driver would not matter in the case of an official heat race, as the weight limit is raised in such cases.

Your calculation is very nice, but how would the gas reach the rear tires? There would have to be a direct connection. And above all, would something that "melts" at 5 degrees be used for cooling something that gets 100 to 140 degrees hot (basket + tires)? 5 kg of dry ice "melts" outdoors at 30 degrees in about half an hour. Sure, the container would be well insulated, so it would last much longer, but considering the energy and temperatures generated by an F1 car when braking... an F1 car generates 2.8 MW of energy every time it brakes, enough to power a small town for 14 hours. So the forces, energy, and heat are enormous. And a little dry ice with a direct connection... I find it hard to imagine that this would survive for any length of time, and it would be a very ineffective cooling system, especially since it would be difficult to "adjust." Much more effective and efficient would be a material that melts at 140 degrees and absorbs the heat up to that point. But anyway, it's all speculation. I find it hard to imagine. What is clear to me is that McLaren has definitely done something with the brakes. The burning brakes and the problems they had clearly indicate this. However, I am NOT saying that this is one of the systems that has been and continues to be the subject of so much speculation.

But can it be ballast? it will disappear as the race goes on? Can't this only be extra weight on top of the minimum weight?

[Andi76]

this is pure speculation

let's assume they are cooling only rear wheels

it' 3-4 litres, dry ice density is about 1,5 so it's 4,5-6kg

6 kg of dry ice generates 3300 litres of CO2.

for a 90 minutes race it's 18,3 litres/minute (or 0,3 l/sec) of 5C CO2 for each wheel

again, this is pure speculation but nobody add 4,5-6kg of weight on a F1 car just too cool the drivers (and the mandatory cooling equipment by FIA is totally different)

Most cars in 2025 will be 5 to 10 kg below the minimum weight. In 2023, the Alpine was already 8 kg below the weight limit. Placing 5 kg in the center of the front axle should therefore not be a problem, and ballast so far forward would not be unusual. In 2006, Ferrari had ballast right at the front of the nose... Of course, there were no regulations regarding weight distribution at that time, but the current regulations allow for a margin of approximately 12 kg. Even additional weight to cool the driver would not matter in the case of an official heat race, as the weight limit is raised in such cases.

Your calculation is very nice, but how would the gas reach the rear tires? There would have to be a direct connection. And above all, would something that "melts" at 5 degrees be used for cooling something that gets 100 to 140 degrees hot (basket + tires)? 5 kg of dry ice "melts" outdoors at 30 degrees in about half an hour. Sure, the container would be well insulated, so it would last much longer, but considering the energy and temperatures generated by an F1 car when braking... an F1 car generates 2.8 MW of energy every time it brakes, enough to power a small town for 14 hours. So the forces, energy, and heat are enormous. And a little dry ice with a direct connection... I find it hard to imagine that this would survive for any length of time, and it would be a very ineffective cooling system, especially since it would be difficult to "adjust." Much more effective and efficient would be a material that melts at 140 degrees and absorbs the heat up to that point. But anyway, it's all speculation. I find it hard to imagine. What is clear to me is that McLaren has definitely done something with the brakes. The burning brakes and the problems they had clearly indicate this. However, I am NOT saying that this is one of the systems that has been and continues to be the subject of so much speculation.

But can it be ballast? it will disappear as the race goes on? Can't this only be extra weight on top of the minimum weight?

Of course, it COULD. As I said, most teams are several kilos below the weight limit, and there is a margin of approx. 12 kg in terms of weight distribution. BUT – it wouldn't make much sense, because you would have to start with excess weight, which would cost 0.1 to 0.2 tenths. Something like that would only be beneficial in qualifying, where you want to have a weight distribution that is slightly more towards the front axle. Considering that you are not allowed to make any changes for the race, this would actually be a theoretical possibility in qualifying to have a weight distribution that favors the front axle a little more, but with the disadvantage of 5 kg of excess weight, which would probably outweigh any advantage.

[mwillems]

Most cars in 2025 will be 5 to 10 kg below the minimum weight. In 2023, the Alpine was already 8 kg below the weight limit. Placing 5 kg in the center of the front axle should therefore not be a problem, and ballast so far forward would not be unusual. In 2006, Ferrari had ballast right at the front of the nose... Of course, there were no regulations regarding weight distribution at that time, but the current regulations allow for a margin of approximately 12 kg. Even additional weight to cool the driver would not matter in the case of an official heat race, as the weight limit is raised in such cases.

Your calculation is very nice, but how would the gas reach the rear tires? There would have to be a direct connection. And above all, would something that "melts" at 5 degrees be used for cooling something that gets 100 to 140 degrees hot (basket + tires)? 5 kg of dry ice "melts" outdoors at 30 degrees in about half an hour. Sure, the container would be well insulated, so it would last much longer, but considering the energy and temperatures generated by an F1 car when braking... an F1 car generates 2.8 MW of energy every time it brakes, enough to power a small town for 14 hours. So the forces, energy, and heat are enormous. And a little dry ice with a direct connection... I find it hard to imagine that this would survive for any length of time, and it would be a very ineffective cooling system, especially since it would be difficult to "adjust." Much more effective and efficient would be a material that melts at 140 degrees and absorbs the heat up to that point. But anyway, it's all speculation. I find it hard to imagine. What is clear to me is that McLaren has definitely done something with the brakes. The burning brakes and the problems they had clearly indicate this. However, I am NOT saying that this is one of the systems that has been and continues to be the subject of so much speculation.

But can it be ballast? it will disappear as the race goes on? Can't this only be extra weight on top of the minimum weight?

Of course, it COULD. As I said, most teams are several kilos below the weight limit, and there is a margin of approx. 12 kg in terms of weight distribution. BUT – it wouldn't make much sense, because you would have to start with excess weight, which would cost 0.1 to 0.2 tenths. Something like that would only be beneficial in qualifying, where you want to have a weight distribution that is slightly more towards the front axle. Considering that you are not allowed to make any changes for the race, this would actually be a theoretical possibility in qualifying to have a weight distribution that favors the front axle a little more, but with the disadvantage of 5 kg of excess weight, which would probably outweigh any advantage.

Right but this is my point. But I wouldn't then call that ballast if it takes the car over the minimum weight at the start of the race but hey, it's just wordplay.

However, I wouldn't rule out a benefit in the race as it may actually help add balance and make the front less pointy whilst the car has a full tank. As the car gets lighter from fuel usage, the front gets lighter therefore giving the car a better balance across the race. I don't know if that is what is happening, but if that were the case, I suppose you might call it ballast.

[Andi76]

But can it be ballast? it will disappear as the race goes on? Can't this only be extra weight on top of the minimum weight?

Of course, it COULD. As I said, most teams are several kilos below the weight limit, and there is a margin of approx. 12 kg in terms of weight distribution. BUT – it wouldn't make much sense, because you would have to start with excess weight, which would cost 0.1 to 0.2 tenths. Something like that would only be beneficial in qualifying, where you want to have a weight distribution that is slightly more towards the front axle. Considering that you are not allowed to make any changes for the race, this would actually be a theoretical possibility in qualifying to have a weight distribution that favors the front axle a little more, but with the disadvantage of 5 kg of excess weight, which would probably outweigh any advantage.

Right but this is my point. But I wouldn't then call that ballast if it takes the car over the minimum weight at the start of the race but hey, it's just wordplay.

However, I wouldn't rule out a benefit in the race as it may actually help add balance and make the front less pointy whilst the car has a full tank. As the car gets lighter from fuel usage, the front gets lighter therefore giving the car a better balance across the race. I don't know if that is what is happening, but if that were the case, I suppose you might call it ballast.

Well, that's not entirely correct like that. More weight at the front means a more pointed front. The rear of the car loses weight much faster than the front because it loses many times more mass in gasoline than in "ice," so it would keep the front more pointed for longer.

[Big Tea]

But can it be ballast? it will disappear as the race goes on? Can't this only be extra weight on top of the minimum weight?

Of course, it COULD. As I said, most teams are several kilos below the weight limit, and there is a margin of approx. 12 kg in terms of weight distribution. BUT – it wouldn't make much sense, because you would have to start with excess weight, which would cost 0.1 to 0.2 tenths. Something like that would only be beneficial in qualifying, where you want to have a weight distribution that is slightly more towards the front axle. Considering that you are not allowed to make any changes for the race, this would actually be a theoretical possibility in qualifying to have a weight distribution that favors the front axle a little more, but with the disadvantage of 5 kg of excess weight, which would probably outweigh any advantage.

Right but this is my point. But I wouldn't then call that ballast if it takes the car over the minimum weight at the start of the race but hey, it's just wordplay.

However, I wouldn't rule out a benefit in the race as it may actually help add balance and make the front less pointy whilst the car has a full tank. As the car gets lighter from fuel usage, the front gets lighter therefore giving the car a better balance across the race. I don't know if that is what is happening, but if that were the case, I suppose you might call it ballast.

How many laps would it take to distil 5kg of water from air? If they are under weight just as well add a a "tweek" as add ballast. Start with 5k of water and dribble it on the way to the grid and replace it late in the race. (Erm, except the cars seem better late in the race
)

[FittingMechanics]

From my quick Copilot fueled calculation (which look alright) the total energy that 4kg of dry ice can absorb is orders of magnitude smaller than what is needed for it to have practical uses.

In fact, it's looks like a single braking zone from 300kmh to 80kmh would be able to sublimate and heat the CO2 to above ambient temperatures.

To me this looks like completely unrealistic.

[CMSMJ1]

reminder

Thread on cars are for actual, physical, evidenced and non speculational things - let's see pictures and review

spitballing about random ideas - not for the car thread.

There'll be some cleaning up

[Brahmal]

There’s been a number of updates to the next technical regs, one of which caught my eye.

Article 3.17.1 has also been amended, with a new clause added which states that suspension fairings “must be internally sealed to prevent any internal airflow.”

I asked this question earlier in this thread:

Could they possibly be ducting some internal airflow through the suspension/driveshaft shrouds into the brake assembly?

Article here: https://www.motorsportweek.com/2025/06/ ... -rulebook/

[Emag]

There’s been a number of updates to the next technical regs, one of which caught my eye.

Article 3.17.1 has also been amended, with a new clause added which states that suspension fairings “must be internally sealed to prevent any internal airflow.”

I asked this question earlier in this thread:

Could they possibly be ducting some internal airflow through the suspension/driveshaft shrouds into the brake assembly?

Article here: https://www.motorsportweek.com/2025/06/ ... -rulebook/

Yes, Stella made a weirdly transparent comment earlier in the season where he hinted that McLaren may be using suspension arms for heat transfer :

An insider speculates: "Perhaps they circulate the air in such a way that it stays cool in the crucial areas and shield the heat through the use of certain materials." Chief Technical Officer Rob Marshall is said to be the father of the system. He has been carrying the concept around with him for years, but has only now made it work. That would be bitter for Red Bull. Marshall was at Red Bull for 17 years before moving to McLaren in early 2024.

Stella also made an interesting statement. "Even when it gets hot, our car stays cool. We've developed a very efficient cooling system." This also affects tire temperatures. If the car as a whole gets too hot, it radiates to the tires. Stella's statement also explains why the McLaren is near the back in terms of top speed. More cooling reduces efficiency.

https://www.auto-motor-und-sport.de/for ... peraturen/

Of course, he just said "heat radiates to the tires", without explicitly mentioning the mechanism, but considering that the suspension arms are the only physical link between the main chassis and the tires, there's not much room for interpretation.

Vanja also read the statement the same way :

cooling tyres through secret suspension arm channels, they are surprisingly open about it

However, the way he (Stella) stated it, is a little bit weird :

If the car as a whole gets too hot, it radiates to the tires.

This sort of implies that the car is transferring heat towards the tires to stay cool, as opposed to the other way around (heat from tries being transferred towards the chassis), which doesn't sound like something you would want. Even if they have some aggressive cooling solution that normally would keep tires cold, it doesn't sound like a good idea to rely on residual heat from other components to heat up the tires.

Either way, we can't really know for sure how such an efficient cooling solution works, both for the "core" of the car as well as the rear tires. But, as I have previously stated before, I personally believe that the whole thing works as a "system" with the entire rear end of the car designed to accommodate this temperature management solution, as opposed to it being entirely concentrated into one cleverly designed part (e.g brake ducts). Could internal ducting in the rear suspension arms be part of the solution? Possibly, but we can't know for sure.

[Luscion]

Upgrades for Canadian GP

[Ben1980]

It seems just test parts.

[SilviuAgo]

MCL39 in Melbourne





@McLaren

[f1rules]

new endplate attachment

[f1rules]

The race
https://www.the-race.com/formula-1/land ... ren-issue/