2025/2026 Hybrid Powerunit speculation

[chrisc90]

Isn't that breaking traction control rules?

5.6 Power unit torque demand
5.6.1 The only means by which the driver may control acceleration torque to the driven wheels is
via a single foot (accelerator) pedal mounted inside the survival cell.

Don’t think that cutting a few injections on shift will break this rule. Also cutting or retarding ignition has been the default action on upshift since the begin of semi-automatic gearboxes.

the elephant in the room is that 350 kW electric motor/generator also driving and braking the crankshaft .....
its contribution will be far bigger than at present, including some behaviours rather like TC and ABS ....
maybe dynamic 'Senna-stutter' effects (pole slips/skips) beyond the scope of the present type of steady-state map rules

That would be interesting. I wonder if the teams could use a loophole that allows the ERS system to work as a traction control on the crankshaft

[gruntguru]

None of this has anything to do with traction control. Skip-firing or MGUK deployment are simply alternatives for changing the torque to the wheels - just like the throttle - which is also computer controlled and not mechanically connected to the pedal.

The MGUK could be used to maintain a load on the engine during gearshifts - helping to match the revs and keep the turbocharger spinning. . . and the energy is stored - not wasted.

[johnny comelately]

...and as the fable unfolded thankfully someone brought the cold water...

[aleks_ader]

Some while back, due to 'emission laws' the self-shifting automatics suffered due to a little device that held the 'throttle' open fractionally not allowing the revs to drop quickly. Would something similar be useful with the new engines? hold the revs up but open wastegates and cut fuel? Could RPM stay high(er) and power output be controlled by fuel feed?

Or is this famous 'turbo lag' a thing of the media? Things have advanced much from the old days of turbo

I doubt the even close the throttle on upshift, just retard timing for a few ignitions will give a few ms of reduced torque output, but keep the exhaust flowing. The reduced torque is enough to shift up.

Or leave driver to adapt its style and make best of both worlds. Ofc towards its limits. I guess simulators will work overtime to find right balance.

[NL_Fer]

Well I stay to my initial statement. The shift time is less than 10ms, so probably they will just retard ignition for a few combustions to smooth the torque spike and keep the gas flowing.

[Tommy Cookers]

None of this has anything to do with traction control....
The MGUK could be used to maintain a load on the engine during gearshifts - helping to match the revs and keep the turbocharger spinning. . . and the energy is stored - not wasted.

the MGU-K is relative to the ICE 5 times bigger (and slower in response) than the current one
it's a hindrance to rev matching

in regeneration the K has about 5 times the back torque that the ICE has
ie PU over-run torque is about 2.5 x the current PU's (and of course proportionate to wheel rpm) ....
when braking any rear wheel under-rotation reduces the rear braking - how isn't this a driver aid ? (poor man's ABS ?)
when accelerating rear wheel over-rotation reduces the MU-K torque - how isn't this a driver aid ? (poor man's TC ?)

[gruntguru]

I really don't see your point. Adding rotational inertia has a similar effect but is not a benefit - damping response to the controls.

[Tommy Cookers]

None of this has anything to do with traction control....
The MGUK could be used to maintain a load on the engine during gearshifts - helping to match the revs and keep the turbocharger spinning. . . and the energy is stored - not wasted.

REWRITTEN

the MGU-K is relative to the ICE 5 times bigger than the current one ... it's .....
a hindrance to rev matching - I believe it's still less responsive than the ICE
(liquid cooling I discount as (1) it isn't the H and (2) servo design methods for response purposes ignore overheating)

the present PU mapping rules amount to a default constant power response to wheel-spin ie a 'poor man's TC' effect
but there's no rules for wheel-slip throttle-off ie braking .....

in regeneration the K has about 5 times the back torque that the ICE has
PU back torque in braking is about 5 x the current PU's at low rpm (and about 2.5 x at high rpm)
so in braking the rear wheel-slip default is reduced rear braking - from the reduction in PU back torque with rpm
this is a big increase in 'poor man's ABS effect' over the present system's (itself an advantage over non-KERS systems)

does this increase amount to a 'driver aid' ie something that should not be allowed ?
or is it ok - because F E has it ?

[gruntguru]

Not sure I buy the concept of electric machines being less "responsive" than the ICE. Anecdotally EV's with far greater outputs than the F1 MGUK have faster throttle response than ICE vehicles. This is time response of course - in terms of rpm response:

Isn't the torque/rpm characteristic open slather? Throttled ICE's typically have a rapid decline in torque/rpm at some point - even power/rpm declines rapidly after the peak - particularly at part throttle. With electronic control of engine output this decline can be very rapid indeed - the key here being that the driver's foot must determine the rpm where torque begins to fall off.

[Big Tea]

Not sure I buy the concept of electric machines being less "responsive" than the ICE. Anecdotally EV's with far greater outputs than the F1 MGUK have faster throttle response than ICE vehicles. This is time response of course - in terms of rpm response:

Isn't the torque/rpm characteristic open slather? Throttled ICE's typically have a rapid decline in torque/rpm at some point - even power/rpm declines rapidly after the peak - particularly at part throttle. With electronic control of engine output this decline can be very rapid indeed - the key here being that the driver's foot must determine the rpm where torque begins to fall off.

Will the rotor be geared at all? It will take time to run up, but this will be reduced by gearing wont it?

I do not mean selectable or variable gearing, just direct cog to cog reduction as I assume the max rpm will be way higher than 12K (ish). a 4 to one means it has a quarter of the response time and torque from very low

[wuzak]

Isn't the torque/rpm characteristic open slather?

For the ICE or MGUK?

The ICE is constrained by fuel flow rules, ramping up in proportion to rpm to 10,500rpm, after which it remains constant.

MGUK has limits on maximum torque and rpm, but not how that is delivered across the rpm range, as far as I can recall.

I suspect most of the MGUK deployment will happen out of corners, particularly slow corners where the rpm of the ICE has to drop. And it will taper off quickly.

It will be like the old LMP1s, where they are very quick off the line, but the acceleration tapers off quickly.

The current LMh and LMDh regulations have a set power curve for the combined ICE and MGUK with respect to rpm, with wiggle room for adjusting balance of performance.

[gruntguru]

For the PU as a whole. This rule does in fact limit how quickly the torque drops off after torque peak. (The throttle position determines the rpm where torque peaks).

5.6.4 At any given accelerator pedal position and above 4,000rpm, the driver torque demand map must not have a gradient of less than – (minus) 0.045Nm/rpm.

[johnny comelately]

For the PU as a whole. This rule does in fact limit how quickly the torque drops off after torque peak. (The throttle position determines the rpm where torque peaks).

5.6.4 At any given accelerator pedal position and above 4,000rpm, the driver torque demand map must not have a gradient of less than – (minus) 0.045Nm/rpm.

"There is a rule crying out to be validated" said the progressives

[wuzak]

For the PU as a whole. This rule does in fact limit how quickly the torque drops off after torque peak. (The throttle position determines the rpm where torque peaks).

5.6.4 At any given accelerator pedal position and above 4,000rpm, the driver torque demand map must not have a gradient of less than – (minus) 0.045Nm/rpm.

There is a limitation of MGUK power above 300km/h.

The power that the MGUK can send to the ICE/drivetrain is reduced by 5kW for every 1km/h from 300 to 340km/h, after which MGUK power is limited to 150kW.

With (theoretically) around 3/4 of the power of the current cars at 340km/h, drag of the 2026 cars will have to be drastically reduced for these speeds to be reached.

[wuzak]

Also, when the fuel available for the race is reduced to 70-75% of the energy of the current regulations, how will they complete races in comparative time?

Drag will be reduced, but surely weight would have to be reduced significantly also? The PU regulations show only a small saving of weight over the current PUs.