2025/2026 Hybrid Powerunit speculation

[Tommy Cookers]

... But could a front generator make the front brakes smaller and lighter?
I know they’re already lightweight, but maybe you could make other parts in the wheel lighter too?

Look at what YASA just achieved. though that’s still in lab conditions. And for a few seconds
https://www.carscoops.com/2025/10/merce ... r-1000-hp/

of course the disc motor/generator isn't new (and yes it's really good at being disc-shaped)
but relative to the conventional it has more rotational inertia
ie more braking work (and accelerating work) may be needed not less

some drawbacks will be greater with the (direct drive) approach as suggested above ie low rpm high torque
consider that the MGU-K chosen is 50000 - 60000 rpm not the 1500 wheel rpm

IIRC lumps of stuff in the wheels are F1-illegal

[dren]

https://www.planetf1.com/news/audi-f1-2 ... comparison

Merc - 420 kilowatts (571bhp) - 50.4% eff

Ferrari - Close behind
Honda - Not far behind
Red Bull - ?

Audi - 400 kilowatts (536bhp) - 48% eff

I expect the current PU manufacturers to all be in the same ballpark with the ICE. It'll come down more to control electronics and the extra harvesting they are able to do.

[DenBommer]

... But could a front generator make the front brakes smaller and lighter?
I know they’re already lightweight, but maybe you could make other parts in the wheel lighter too?

Look at what YASA just achieved. though that’s still in lab conditions. And for a few seconds
https://www.carscoops.com/2025/10/merce ... r-1000-hp/

of course the disc motor/generator isn't new (and yes it's really good at being disc-shaped)
but relative to the conventional it has more rotational inertia
ie more braking work (and accelerating work) may be needed not less

some drawbacks will be greater with the (direct drive) approach as suggested above ie low rpm high torque
consider that the MGU-K chosen is 50000 - 60000 rpm not the 1500 wheel rpm

IIRC lumps of stuff in the wheels are F1-illegal

Okay, but maybe I wasn’t clear.

I wouldn’t place an axial-flux generator in the wheel, but in the nose, with driveshafts to the front wheels. Like in formula E.

Am I clearer now?

[Tommy Cookers]

IIRC there was a rule (B.A.R. ? c.2000 ?) that banned any rotational interconnection between the front wheels

so maybe 2 chassis-mounted axial-flux gearhead machines each with its own driveshaft to its own front wheel
each somewhat integral with its own (inboard) friction brake and clearly common only at the ES

the ES and the CEs and their cooling systems will be bigger ... and again ....
these 'lighter' A-F machines will be harder to accelerate ie 'heavier' (they are bigger stores of mechanical energy)

[wuzak]

IIRC there was a rule (B.A.R. ? c.2000 ?) that banned any rotational interconnection between the front wheels

Benetton had a front diff and axles in 1999 for torque transfer as well.

[saviour stivala]

There was a rule (BAR c 2000) that banned any rotational inter connection between the front wheels. The BAR used system, Despite being ordered off the cars at its debut in Germany, it was later deemed legal. The formula 1 rules in 2000 that later banned the interconnection of front wheels were part of broader ban on active suspension systems. In 2004 BAR used a front torque transfer system on the front wheels that linked both front wheels via drive shafts, to balance the braking forces, allowing drivers to brake later into a corner. Benetton in 1999, first ran in 1989, in an attempt to counter the tendency for front wheels to lock under braking when cornering, used a viscous coupling/ a fluid differential linking the front wheels via drive shafts, it was stuck on the bulkhead and intruded in the crash area. They worked with GKN and XTRAC to design and build a unit that would give the right slip characteristics.

[wuzak]

The posts by wuzak and diffuser, contrary to what you claim does not convince me otherwise, because I believe solidly that the 2026 MGU-K would only be able to deploy energy when car is accelerating, and it would only be able to harvest energy when the car is decelerating.

Why do you think that?

Is there something in the rules that point in that direction?


There are rules for recovery when under full throttle and at part throttle.

Nothing I've seen says the MGUK can only be used when slowing the car down.

[saviour stivala]

The posts by wuzak and diffuser, contrary to what you claim does not convince me otherwise, because I believe solidly that the 2026 MGU-K would only be able to deploy energy when car is accelerating, and it would only be able to harvest energy when the car is decelerating.

Why do you think that?

Is there something in the rules that point in that direction?


There are rules for recovery when under full throttle and at part throttle.

Nothing I've seen says the MGUK can only be used when slowing the car down.

First, I stand with what I wrote, ''The MGU-K would only be able to deploy energy when car is accelerating, and it would only be able harvest energy when the car is decelerating''. Which in turn means that when the car is accelerating, the driver is on-throttle. And when the car is decelerating, the driver is off-throttle. You, WUZAK are interpreting the rules wrongly. There will be no energy recovery under throttle (car accelerating), What there will be is energy deployment saving. ''The 2026 rules will include track-dependent energy deployment restrictions under full throttle'', to ensure safety and maintain race balance, specifically, cars will not be allowed to use full electrical power on certain tracks, to prevent dangerously high speeds. The rules will also feature a gradual ramp-down of battery power as speeds increase to manage energy output. There will also be speed dependent tapering, the amount of battery power that can be used will decrease as the car's speed increases.

[wuzak]

First, I stand with what I wrote, ''The MGU-K would only be able to deploy energy when car is accelerating, and it would only be able harvest energy when the car is decelerating''. Which in turn means that when the car is accelerating, the driver is on-throttle. And when the car is decelerating, the driver is off-throttle.

What there will be is energy deployment saving. ''The 2026 rules will include track-dependent energy deployment restrictions under full throttle'', to ensure safety and maintain race balance, specifically, cars will not be allowed to use full electrical power on certain tracks, to prevent dangerously high speeds. The rules will also feature a gradual ramp-down of battery power as speeds increase to manage energy output. There will also be speed dependent tapering, the amount of battery power that can be used will decrease as the car's speed increases.

The rule about ramp down rate:
C5.12.6 The driver maximum power demand must not be reduced at any greater than the rates defined below:
a. 50kW in any 1s period at Competitions where the FIA determines that the power limited distance exceeds 3500m. These Competitions and the vehicle fundamentals used for the calculation of the power limited distance may be found in the document FIA-F1-DOC-Cxxx.
b. 100kW in any 1s period at all other Competitions.
Furthermore, the total power reduction is limited to a maximum of 600kW and the resulting electrical DC power of the ERS-K must remain above −250kW.

Seems pretty clear that (a) this refers to the driver at full throttle and (b) the MGUK power is reduced below 0, that is, it is harvesting. The maximum harvesting under full throttle is 250kW.

You, WUZAK are interpreting the rules wrongly. There will be no energy recovery under throttle (car accelerating)

If I am wrong, I am not the only one.

You are the only one that seems to be of the impression that that "there will be no energy recovery under throttle (car accelerating)".

I ask you to support your contention with a specific rule that forbids harvesting under acceleration.

Certainly they are not permitted to recover energy when accelerating with maximum power demand, as the PU must match that demand, subject to battery state of charge and speed, but they do not always accelerate at maximum power demand.

In traction limited acceleration they cannot use maximum power demand, so there will be times where it is possible to harvest energy while still accelerating.

[mzso]

IIRC there was a rule (B.A.R. ? c.2000 ?) that banned any rotational interconnection between the front wheels

so maybe 2 chassis-mounted axial-flux gearhead machines each with its own driveshaft to its own front wheel
each somewhat integral with its own (inboard) friction brake and clearly common only at the ES

the ES and the CEs and their cooling systems will be bigger ... and again ....
these 'lighter' A-F machines will be harder to accelerate ie 'heavier' (they are bigger stores of mechanical energy)

If one reg change is required (for front regen) why wouldn't they change two?
I don't get why this comes up all the time. If the intention was to allow something, they would adjust all relevant rules.

[saviour stivala]

With the removal of the MGU-H in 2026, the energy recovery system will no longer recover energy from the turbocharger's heat. This will put exclusive reliance on breaking as the only source of energy recovery, recovery will be from kinetic energy captured by MGU-K during braking.

[Tommy Cookers]

... the energy recovery system will no longer recover energy from the turbocharger's heat....
... braking as the only source of energy recovery ....

it can recover some from the KE of the 120000 rpm turbocharger ....
being connected by induction gas and exhaust gas to the ICE/MGU-K combo called the PU

and the 2026 system will recover more energy that's hidden in the KE of the ICE & MGU-K rotation
because the MGU-K is much bigger and faster? rotating typically 50000 rpm
often times per lap the rpm falls eg to 50% so 75% of that KE is recovered and stored in the ES
and many times per lap the rpm falls after it has just been raised by spending fuel
as part of up-shifting and even as part of down-shifting

[saviour stivala]

Doubling the amount of energy that can be recovered per lap to 8.5 megajoules, this will require drivers to use new braking strategies to efficiently charge the battery, as the system will have a higher power output of up to 350 kw.

[wuzak]

With the removal of the MGU-H in 2026, the energy recovery system will no longer recover energy from the turbocharger's heat. This will put exclusive reliance on breaking as the only source of energy recovery, recovery will be from kinetic energy captured by MGU-K during braking.

The MGUK recovers energy by braking the ICE, but that does not mean it is braking the car, or that the driver is braking.

The MGUK can be used to control the output of the PU to match the driver's demand.

[saviour stivala]

When the MGU-K is recovering energy, the car is decelerating, the driver has lifted off throttle, and the driver is using the brakes. When a driver lifts off the throttle, the MGU-K switches to a generator, converting the car's kinetic energy into electrical energy to charge the battery. This greats a form of ''engine braking'' that helps decelerate the car. The car's electronic control unit (ECU) manages the split between the braking power from the MGU-K and the hydraulic brakes. This ensures that the total deceleration feel natural to the driver.