2025/2026 Hybrid Powerunit speculation

[wuzak]

And what is the harvesting limit per lap?.

9MJ.

So 4.5 times the allowed recovery from the MGUK with 2.91 times the maximum recovery power (350kW vs 120kW).

Deployment currently is limited at 4MJ from the ES to MGUK. Deployment (energy) will be unlimited in 2026.

[wuzak]

If we assume that the fuel energy allowed for the race is 3000MJ (2014 rules were 100kg/h fuel flow and 100kg fuel for the race), and that 9MJ/lap is recovered and then deployed at every track, then the electrical energy recovered/used would be on average, for this season's races, 546MJ, or 18.2% of fuel energy. Slightly more than double for the amount of energy that the ICE can output.

The maximum would be Monaco (702MJ, 23.4%) and the minimum would be Spa (396MJ, 13.2%).

Of course, shorter tracks like Monaco are unlikely to allow the recovery of 9MJ, and at least some of the electrical energy would come from using the MGUK as a generator, driven by the ICE.

[wuzak]

This is a plot of the maximum power mode used at Hungary in 2021



I would think that this would be similar in 2026, though some of the durations would be shorter, as the 23.1s is not much less than the maximum that could be recovered in a lap. It means that the rest of the lap would be at lower power, or probably spent recovering power.

[saviour stivala]

If we assume that the fuel energy allowed for the race is 3000MJ (2014 rules were 100kg/h fuel flow and 100kg fuel for the race), and that 9MJ/lap is recovered and then deployed at every track, then the electrical energy recovered/used would be on average, for this season's races, 546MJ, or 18.2% of fuel energy. Slightly more than double for the amount of energy that the ICE can output.

The maximum would be Monaco (702MJ, 23.4%) and the minimum would be Spa (396MJ, 13.2%).

Of course, shorter tracks like Monaco are unlikely to allow the recovery of 9MJ, and at least some of the electrical energy would come from using the MGUK as a generator, driven by the ICE.

But the engineer involved with RBPT design said that driving the 'K' with ICE will not be allowed

[johnny comelately]

Disclaimer: not my field
But can they harvest enough from full rear wheel retardation from MGU K and/or with (as mentioned before) front wheel harvest?

[saviour stivala]

‘’the energy harvested in each lap must not exceed 9mj, this limit applies to the energy going out of CU-K’’. when the 2026 power unit rules were being formulated there was strong speculation that harvesting by front wheels braking would have to be introduced (added), but going through the technical rules which have since been published, one can find nothing about such harvesting. On a different subject, if I understood things correctly going through the rules as are, the turbocharger compressor intake throttling system used at present will be no more from 2026.

[Tommy Cookers]

‘’Energy is also recovered using lift and coast – The driver lifts off the throttle early and the MGU-K helps slow the car before the brakes are applied’’ oh dear that RBPT engineer involved in the RETECH interview must have been terribly wrong opinionizing that in his expert opinion running the MGU-K by the engine will not be allowed....

on what planet is K generation accelerator-off brakes-off "running the MGU-K by the engine" ?
not on planet Earth

[saviour stivala]

The RBPT engine design team leader engineer swaying that “running the MGU-K with the engine will not be allowed” meant that the MGU-K will not be allowed/permitted to harvest unless the brakes are applied (running the MGU-K by the engine). In Actual fact and simple terms, the MGU-K being attached to the crankshaft through its own gearbox, the MGU-K is always in rotation when the engine is running, But it Can be run free of any in or out loads as well as in motor mode and generator mode. In motor mode it will be contributing electrical power to the crankshaft, while when triggered into generator mode by the brake pedal it will harvest energy by the engine crankshaft because of engine braking. When that mode takes place the MGU-K will contribute significantly braking power (retardation). And once again, when the driver lifts and coast the brake pedal is not applied, which in turn and contrary to some believe. The MGU-K is not harvesting.

[Tommy Cookers]

The RBPT engine design team leader engineer swaying that “running the MGU-K with the engine will not be allowed” meant that the MGU-K will not be allowed/permitted to harvest unless the brakes are applied (running the MGU-K by the engine). In Actual fact and simple terms, the MGU-K being attached to the crankshaft through its own gearbox, the MGU-K is always in rotation when the engine is running, But it Can be run free of any in or out loads as well as in motor mode and generator mode. In motor mode it will be contributing electrical power to the crankshaft, while when triggered into generator mode by the brake pedal it will harvest energy by the engine crankshaft because of engine braking. When that mode takes place the MGU-K will contribute significantly braking power (retardation). And once again, when the driver lifts and coast the brake pedal is not applied, which in turn and contrary to some believe. The MGU-K is not harvesting.

Mr RBPT didn't say that

'lift and coasting' (brake-off anyway) MGU-K 'harvest' recovers for reuse car and PU translational and rotational KE
just what a hybrid road car does
banning this would be stupid and perverse - that's why it isn't banned
the major point of the K being to recover KE rather than waste it by using brakes
and ... this certainly isn't 'running the MGU-K with the engine'

other things aren't banned either
yes of course now having the K as big as the ICE will alter priorities

[saviour stivala]

Mr RBPT said that he doesn’t think the MGU-K will be allowed to be run by the engine. And that can be taken that it is not allowed in the present formula. During lift and coast (brake pedal off) 'K' will not harvest.

[wuzak]

Mr RBPT said that he doesn’t think the MGU-K will be allowed to be run by the engine. And that can be taken that it is not allowed in the present formula. During lift and coast (brake pedal off) 'K' will not harvest.

Lift-and-coast the driver lifts off the throttle. So the chassis is slowing down through aero resistance and engine braking.

The engine braking includes energy recovery from the MGUK.

In current F1 I believe there are 4 phases at the end of a straight
1. Max self-sustaining power - the ICE is making the maximum power, the MGUH is recovering all it can from the turbo and sending it to the MGUK.
2. Max ICE power with MGUH storing in ES. The MGUH stops feeding the MGUK but then feeds the ES. This is important in current F1 because the MGUK can only recover 2MJ to the ES, but is allowed to deploy 4MJ from the ES.
3. Lift-and-Coast - driver lifts off the throttle, and the car slows by combination of drag and engine braking (ie MGUK).
4. Braking - driver brakes the car and MGUK recovers as much power as possible.

At the end of the straight the lights flash to warn following drivers that the car is harvesting and may slow down earlier than expected.

The current cars are allowed to recover 2MJ from MGUK to ES. They cannot do this with braking alone, which gives around 1MJ to 1.5MJ per lap on most circuits. The remainder comes from lift-and-coast.

As far as using the engine to drive the MGUK as a generator, I don't believe there is a specific rule that outlaws it in the current regulations. But it may have been put into a technical directive that we do not get to see.

It may also be something to do with Ferrari's 2019 power unit issues. It always seemed that they had more ERS than the other teams, though the rumours have all pointed to cheating the fuel flow meter. We do know that Ferrari were doing something that the FIA didn't like, so it could be either, or neither of these options.

For 2026 it would not be possible to recover 9MJ per lap through braking alone, and unlikely through braking and lift-and-coast. As I said earlier, the allowed recovery power of the MGUK is 2.9 times current regulations, but allowed energy recovery is 4.5 times. Either lift-and-coast is going to be very long, or they will be allowed to drive the MGUK with the motor.

Another clue that driving the MGUK with the engine will be permitted is this:

5.14.5 The driver maximum torque demand may only be reduced at a maximum rate of 100kW in any 1s period and the power reduction will be limited to a maximum of 450kW.

The MGUK is going to be deploying power to the wheels when the driver first reaches full throttle. It is likely to be the full 350kW for a second or two, like the full power maps video above. The driver will still have his foot to the floor along the straight, but the ERS can't deliver its full power for very long, so it will be reduced in power.

The fact that the torque demand can be reduced by 450kW, 100kW more than the MGUK power, is telling. It is quite possible that at the end of the straight the ICE will be making its full 400kW, but the MGUK will be recovering 100kW, so the output at the wheels is 300kW.

If the car can brake or lift-and-coast for 20s with 350kW recovery, that is 7MJ. Then another 20s with MGUK recovering 100kW while ICE is at full power gives the other 2MJ to make up 9MJ.

[saviour stivala]

“Another clue (that the RBPT engine team design leader must have not seen) that driving the ‘K’ with the engine will be permitted’’. I personally will give more weight to what a F1 engine design team leader believes and says.
Rear lights flashing when rain is not involved indicates that ‘K’ have stopped deploying. And when ‘k’ stops deploying it doesn’t mean it is harvesting that is unless the driver activates the brake pedal.
During lift and coast brake pedal is not activated so engine braking does not include ‘K’ retardation.

[wuzak]

“Another clue (that the RBPT engine team design leader must have not seen) that driving the ‘K’ with the engine will be permitted’’. I personally will give more weight to what a F1 engine design team leader believes and says.
Rear lights flashing when rain is not involved indicates that ‘K’ have stopped deploying. And when ‘k’ stops deploying it doesn’t mean it is harvesting that is unless the driver activates the brake pedal.
During lift and coast brake pedal is not activated so engine braking does not include ‘K’ retardation.

I remind you that the F1 engine team leader is working on the ICE, he has only started working in F1 and has little or no involvement with the ERS side or the area of calibration (putting it all together).

He is probably right about the current rules not allowing the motor driving the MGUK as a generator, though it is not explicitly in the rules.

The MGUK generating under braking is the same mechanism as when lift-and-coasting - essentially engine braking.

If the 2026 rules don't allow using the engine to drive the MGUK as a generator, can you explain why the rules allow the power to reduce by 450kW while under full torque demand?

[saviour stivala]

Personally I am certainly convinced that an engine design team leader will know exactly what he is talking about, regardless of what you and others on here believe.
Yes. The ‘K’ ‘HARVESTING’ under braking is the same mechanism when lift-and-coasting, essentially engine braking, But apart from the engine braking, which means the engine is as explained elsewhere, is driving the ‘K’, it is during lift and coast driving the ‘K’ free of any ‘IN’ or ‘OUT’ load as both the throttle which activates deploying and the brake pedal, which activates harvesting are not activated – being used.

[wuzak]

Personally I am certainly convinced that an engine design team leader will know exactly what he is talking about, regardless of what you and others on here believe.

I believe in his interview he explained he doesn't know all about the ERS side of things.

Yes. The ‘K’ ‘HARVESTING’ under braking is the same mechanism when lift-and-coasting, essentially engine braking, But apart from the engine braking, which means the engine is as explained elsewhere, is driving the ‘K’, it is during lift and coast driving the ‘K’ free of any ‘IN’ or ‘OUT’ load as both the throttle which activates deploying and the brake pedal, which activates harvesting are not activated – being used.

Why do you think that recovery is activated by the brake pedal?

Certainly deployment is not controlled completely by the throttle pedal - it doesn't always deploy when the throttle is activated.