2025/2026 Hybrid Powerunit speculation

[Tommy Cookers]

.. regenerating braking ... is shared by the MGU-K regenerating 'braking' effect and the rear wheels hydraulics ...

well yes ... in concept
(when speed's reduced enough the friction brakes can idle and the rear braking can be all regenerative)

but I don't think this (low-speed regen) is done in 2025
full regen power is small - it can be available at low speeds but that's unimportant given the MGU-H generation

of course regen power is much larger and much more important in the 2026 cars ....
rear friction brakes are gone by about 165 kph then regenerative rear braking steadily falls from the full 350kW
of course as speed falls further the aero DF and so wheel grip falls further but .....
the desired wheel torque is increased due to the down-shifting and then by an increase in MGU-K torque but ..
the desired wheel torque is unattainable due to insufficient wheel grip and so ....
the regen power attainable is about 175 kW at 100 kph and 80 kW at 50 kph

the MGU-K is of course a synchronous machine ...
ie the (magnetic pole pair) rotor is in effect fixed to the rear wheels and ...
the control electronics CE and stator (coils) together amount to a rotating magnetic pole pair
a thousand times a second rotor position is timed and action taken to maintain synchronicity between rotor and stator
eg wheel under-rotation is prevented automatically regardless of ongoing torque demands for control of regen power

it's ABS !
" but not as we know it "
it has the benefit of automatically maximising the regenerated energy

similar action (against wheel over-rotation) could occur when the MGU-K is acting as a motor
there might appear to be a grey area eg when compared with 2014-2025 permissible PU response maps

[lucafo]

Yes, the simplest way is to open the throttles on the overrun during braking.

How does that relieve cylinder pressure?

and ...
what is the turbocharger doing ?
to conserve turbocharger rpm it might be circulating air not compressing it (how the 917 turbo changed our world)
and now it has variable geometry inlet vanes for control without the traditional throttling losses

the 'engine braking' torque is increased at the rear wheels with every downshift below the high gear
so EB is reduced if there is downshifting only at the end of braking (but the MGU-K designers don't like this)

It should have been considered in this new regulation the continuous variable transmission...

[mzso]

current F1 engines have steel pistons as aluminium alloy has insufficient fatigue strength at the temperatures involved
(as they more than SI ever has before release the combustion heat in-cylinder before expansion)

and the engines have structural cut-outs in the head for the separate (CuBe) valve seat rings
steel heads would have no cut-outs - that might make more room for bigger valves/ports ...
or enable some other feature in eg the jet injector system

I thought Beryllium was banned universally, not just from pistons.

Highly unliely that supercapacitors will replace the ES (battery) in F1.

Supercapacitor is just a fancy name for a electric double layer capacitor, EDLC. Also known as ultracapacitor. They fall somewhere between capacitors and battery in capacity and charge/recharge times.
Roughly categorized, batteries operate in minutes to hours time domain, EDLC seconds to minutes, capacitor < 1 second.
I think what people mean by supercapacitor is a non excisting thing with super properties. What we would like to have, not the excisting supercapacitors of today.

I think they qualify purely based on capacity. Their energy densities don't reach li-ion capacities, but better than other common chemistries. I guess they would only make sense if the stored energy would be very little, but the power would be high with regen braking. Nowadays it seems li-ion can easily handle it with less weight for the same energy.

[mzso]

Are there ways of reducing engine braking so that maximum harvesting by the MGU?

Is it possible for compression stroke pressure to be released out through the spark or injector ports?

Tommy Cookers previously detailed that there's already no engine braking as such.

Engine braking (lift off throttle) adds to the braking force of the brakes, the use of both the brakes and engine resistance will result in more braking force, the more braking force, the more energy harvesting.

Engine braking in no way would result in in more harvesting, just more wasted energy.

[mzso]

Highly unliely that supercapacitors will replace the ES (battery) in F1.

Supercapacitor is just a fancy name for a electric double layer capacitor, EDLC. Also known as ultracapacitor. They fall somewhere between capacitors and battery in capacity and charge/recharge times.
Roughly categorized, batteries operate in minutes to hours time domain, EDLC seconds to minutes, capacitor < 1 second.
I think what people mean by supercapacitor is a non excisting thing with super properties. What we would like to have, not the excisting supercapacitors of today.

I think they qualify purely based on capacity. Their energy densities don't reach li-ion capacities, but better than other common chemistries. I guess they would only make sense if the stored energy would be very little, but the power would be high with regen braking. Nowadays it seems li-ion can easily handle it with less weight for the same energy.

[saviour stivala]

Engine braking contributes to energy recovery because it is one of the three systems that decelerate the the car - (friction brakes, engine braking, and MGU-K braking). Driver-controlled engine braking will be a crucial part of the 2026 formula 1 energy recovery system, with the MGU-K specifically designed to recover energy during the moment a driver lifts off the throttle or lightly brakes in corners, even without active braking.

[DenBommer]

[Badger]

Yes, I’m afraid they will ruin the spectacle. Beyond the basic numbers that don’t make much sense from a performance and regen perspective, they’ve decided to sacrifice arguably the most impressive aspect of the sport. Braking performance. It’s the single most outstanding aspect of F1, and one that is crucial to the wow factor, especially for people who are at the race sat in a grandstand (which are almost all located near braking zones). Now imagine every lap instead of braking at 80 meters down from 300kph, you’re now lifting at 300m, then coasting for 250m, and then braking the final 50m from a much lower speed. It will look like a joke compared to what we have now.

Unfortunately the F1 establishment (FOM, teams, media) have decided to not look too critically at it because they don’t want to ruin the hype, they don’t stand to benefit from that obviously. But sooner or later when reality hits the screen, I am convinced that fans will be shocked, and not in a good way. It will be another lesson in not letting politics dictate entertainment.

[mzso]

Engine braking contributes to energy recovery because it is one of the three systems that decelerate the the car - (friction brakes, engine braking, and MGU-K braking). Driver-controlled engine braking will be a crucial part of the 2026 formula 1 energy recovery system, with the MGU-K specifically designed to recover energy during the moment a driver lifts off the throttle or lightly brakes in corners, even without active braking.

One in no way comes from the other. You're rather confused about what recovery means.

[mzso]

Yes, I’m afraid they will ruin the spectacle.

I'm trying to think up what's left to ruined.

Beyond the basic numbers that don’t make much sense from a performance and regen perspective, they’ve decided to sacrifice arguably the most impressive aspect of the sport. Braking performance.

I'd be surprised if a significant number of people would call braking spectacle. Or care or even notice the brake distance.

[TimW]

The very short braking distance is actually one of the problems of F1, it makes overtaking more difficult. With longer braking distance and regen, that may very well help the spectacle. Drivers can choose to sacrifice regen for a shorter braking distance, to defend or to make an overtake. Regen and deployment strategy becomes much more important.

[saviour stivala]

Engine braking contributes to energy recovery because it is one of the three systems that decelerate the the car - (friction brakes, engine braking, and MGU-K braking). Driver-controlled engine braking will be a crucial part of the 2026 formula 1 energy recovery system, with the MGU-K specifically designed to recover energy during the moment a driver lifts off the throttle or lightly brakes in corners, even without active braking.

One in no way comes from the other. You're rather confused about what recovery means.

The rear wheels can be decelerated by three separate sources, friction from the brakes, resistance from the spinning engine (so called engine braking), and electrical braking that results from harvesting energy by the MGU-K. The driver can adjust each of these effects independently on his steering wheel.

[wuzak]

Now imagine every lap instead of braking at 80 meters down from 300kph, you’re now lifting at 300m, then coasting for 250m, and then braking the final 50m from a much lower speed. It will look like a joke compared to what we have now.

I don't think that will happen.

Instead, the drivers will be on full throttle when the system starts energy recovery, which slows the car down, before braking hard.

There will be a balancing act between recovering under full throttle and under braking, as the former reduces the time that the brakes will be deployed and the amount of energy recovery possible.

I think that if they were allowed more freedom with the active aero there would be some interesting solutions.

For maximum energy recovery they would want to be in low drag mode for braking.

But braking performance requires the downforce for grip, which increases drag and reduces the amount of energy recovery possible.

If they were allowed continuously variable wing adjustment, rather than the 2 positions for 2026, they could adjust the rear wing to maximise rear braking and reduce drag.

[Badger]

The very short braking distance is actually one of the problems of F1, it makes overtaking more difficult. With longer braking distance and regen, that may very well help the spectacle. Drivers can choose to sacrifice regen for a shorter braking distance, to defend or to make an overtake. Regen and deployment strategy becomes much more important.

“The spectacle” isn’t just about the quantity of overtakes. The cars need to be impressive to watch when they aren’t overtaking as well, and massive LiCo into every corner doesn’t exactly scream “pinnacle” to me.

Personally I think overtaking quantity is highly overrated. If it were the number of overtakes that determined how entertaining a motorsport was then F1 would have never become the top motorsport brand. It should be possible to overtake, but also possible to defend from a slightly faster car. That balance is key to F1.

[Badger]

Now imagine every lap instead of braking at 80 meters down from 300kph, you’re now lifting at 300m, then coasting for 250m, and then braking the final 50m from a much lower speed. It will look like a joke compared to what we have now.

I don't think that will happen.

Instead, the drivers will be on full throttle when the system starts energy recovery, which slows the car down, before braking hard.

There will be a balancing act between recovering under full throttle and under braking, as the former reduces the time that the brakes will be deployed and the amount of energy recovery possible.

I think that if they were allowed more freedom with the active aero there would be some interesting solutions.

For maximum energy recovery they would want to be in low drag mode for braking.

But braking performance requires the downforce for grip, which increases drag and reduces the amount of energy recovery possible.

If they were allowed continuously variable wing adjustment, rather than the 2 positions for 2026, they could adjust the rear wing to maximise rear braking and reduce drag.

The 350 kW energy recovery more or less negates the full throttle, hence it will effectively be LiCo even if the engine is still revving (generator mode). The car will start slowing down due to drag and rolling resistance long before the normal braking zone.

My guess is they will be in low drag mode during this LiCo phase to minimise drag losses/maximise regen and time, and then go to high downforce mode for the final braking where you actually need grip.

But you can imagine how it’s going to work fairly easily, because for every second of LiCo you get one second of deployment (assuming full regen and deployment). So if you want 20 seconds of deployment per lap, say 8s at full power and 12s at on average half power, that’s 14 seconds of LiCo you need. That’s a lot of freaking LiCo. Now maybe some of that will be covered by regen mid corner.