2025/2026 Hybrid Powerunit speculation

[michl420]

You guys should not forget, that at 345 kph, the MGUK output is anyway 0 kw. The question will be how many kw are necessary for this speed (low drag mode) and how much from this can the ICE contribute.
Could it be possible, that after 10 sec MGUK assist, the ICE can drive the car with 340 kph alone?

[Badger]

If we use Badger's diagram for Spa, and the maximum ramp down rate.

6s @ 350kW = 2,100MJ deployed
7s 350kW - 0kW = 1,225kJ deployed
5s 0kW to -250kW = 625KJ recovered
5s @ -250kW = 1,250KJ recovered

3,325kJ deployed
1,875kJ recovered

Net usage: 1,450kJ.

But, with this model will the car slow too much to make brake energy recovery negligible?

I didn't make the model to perfect scale on the time axle, I just wanted to roughly describe the different deployment phases I think we'll see.

- I think 6s @ 350 kW is probably a bit long, maybe 4 seconds? Think more "quick punch" out of the corner.
- Active braking might be 3-4 seconds with an average of 225 kW regen or something like that.

I based the 6s on acceleration estimates from 70km/h to 290km/h for current cars.

2026 cars should be similar, with similar power, less weight but less grip.

And won't they want to get to maximum speed as quickly as possible?

For that they will deploy maximum MGUK power for as long as possible.

Also, current braking for Les Combes at Spa is ~ 1.6s per Brembo. The speed only drops t ~ 170-170km/h.

Consider 4 seconds of full deployment. Seconds 1-4 you have 1030 HP (more than we have now), second 5 you have 965 HP, second 6 you have 900 HP, second 7 you have 835 HP, second 8 you have 770 HP, etc. With the low drag mode and the lighter car you will accelerate plenty with these numbers, even when tapering those first few seconds.

Come to think of it 4 seconds of full deployment may be too much. 3 seconds may be more appropriate for a long straight. Especially when you consider that you will be traction limited early in the acceleration phase so you won't need full beans the first second probably.

[michl420]

Is it safe to say that, compared to this year's power units, a greater percentage of total fuel use per lap will be consumed at part-throttle and a lesser percentage consumed by full-throttle running? If so we could see results of part-throttle engine development.

Options for reducing power output:
-throttling of intake air + reducing fuel (typical)
-reducing fuel only while maintaining WOT (if feasible)
-cylinder cutting
-cylinder cutting + independent throttle body control (I see no stipulation that all six butterflies/barrels must move in unison)
-split throttling (use independent throttle body control to vary the a:f of any cylinder w respect to others)

I think part trottle will be less. Next year they must convert as much fuel as possible in propulsion (obvious) and electricity. They will try to run the ICE always with at least 350 kw output. (of course not in hard braking zones)

[wuzak]

Consider 4 seconds of full deployment. Seconds 1-4 you have 1030 HP (more than we have now), second 5 you have 965 HP, second 6 you have 900 HP, second 7 you have 835 HP, second 8 you have 770 HP, etc. With the low drag mode and the lighter car you will accelerate plenty with these numbers, even when tapering those first few seconds.

Come to think of it 4 seconds of full deployment may be too much. 3 seconds may be more appropriate for a long straight. Especially when you consider that you will be traction limited early in the acceleration phase so you won't need full beans the first second probably.

6s acceleration from 70km/h to 290km/h is a 220km/h increase.

4s acceleration would give you a bit more than 220*4/6 = 147km/h increase.

After 4s the speed would be 217km/h+.

But we know the acceleration is not constant, so it will probably be 240-250km/h, still a deficit of 50-40km/h.

It's going to take longer to get to 290km/h than 6s using lower power to accelerate, and the speed vs distance will be lower all along the straight.

We do not know what the current PUs produce, other than it is about 1,000hp. Which is similar to next year.

Assume 400kW for the ICE (often stated target, 48% TE).

First 4s total power 750kW, MGUK deployment 350kW = 1,400kJ

Your ramp rate seems to be 50kW/s, so 7s ramping to get to 0kW deployment.

7 * 350 / 2 = 1,225kJ.

Total energy deployed = 2,625kJ.

But you've deployed for 11s out of 23s. What do you do for the next 12s?

After 6s your scenario would have 100kW less power than my scenario. At 11s it would still be 100kW less, after 12s 50kW less and equal at 13s.

That is a big disadvantage in acceleration and speed along the straight.

[Badger]

Consider 4 seconds of full deployment. Seconds 1-4 you have 1030 HP (more than we have now), second 5 you have 965 HP, second 6 you have 900 HP, second 7 you have 835 HP, second 8 you have 770 HP, etc. With the low drag mode and the lighter car you will accelerate plenty with these numbers, even when tapering those first few seconds.

Come to think of it 4 seconds of full deployment may be too much. 3 seconds may be more appropriate for a long straight. Especially when you consider that you will be traction limited early in the acceleration phase so you won't need full beans the first second probably.

6s acceleration from 70km/h to 290km/h is a 220km/h increase.

4s acceleration would give you a bit more than 220*4/6 = 147km/h increase.

After 4s the speed would be 217km/h+.

But we know the acceleration is not constant, so it will probably be 240-250km/h, still a deficit of 50-40km/h.

It's going to take longer to get to 290km/h than 6s using lower power to accelerate, and the speed vs distance will be lower all along the straight.

We do not know what the current PUs produce, other than it is about 1,000hp. Which is similar to next year.

Assume 400kW for the ICE (often stated target, 48% TE).

First 4s total power 750kW, MGUK deployment 350kW = 1,400kJ

Your ramp rate seems to be 50kW/s, so 7s ramping to get to 0kW deployment.

7 * 350 / 2 = 1,225kJ.

Total energy deployed = 2,625kJ.

But you've deployed for 11s out of 23s. What do you do for the next 12s?

After 6s your scenario would have 100kW less power than my scenario. At 11s it would still be 100kW less, after 12s 50kW less and equal at 13s.

That is a big disadvantage in acceleration and speed along the straight.

Obviously. You deploy more energy on one straight you will go faster there, what about the rest of the lap? I'm suggesting the fastest way around the lap will be to mete out the deployment more evenly across several acceleration zones, especially on a track like Spa where you have more than one long straight.

[gruntguru]

. . . . NO, the regulations do not allow energy recovery under driver maximum power demand.

I don't think anybody is suggesting that. Certainly not myself. What I am saying is - "Under reduced driver power demand - it is permitted for the control system to operate the ICE at higher output than demanded and send the surplus energy to the ES via the MGUK" The following quote from the Tech Regs makes it clear that energy can be harvested under braking AND AT PARTIAL LOAD.


.
The regs go on to specify the limits for Partial Load Harvesting.

.
The following table illustrates a few examples of partial load harvesting limits using the formula above.

.
There is no requirement in the regulations for the brake pedal to be used to initiate Partial Load Harvesting. The teams would be free to do so, but in most cases the degree and frequency of Partial Load Harvesting will be determined by the control system in accordance with the mode setting selected by the driver - not the brake pedal.

[wuzak]

. . . . NO, the regulations do not allow energy recovery under driver maximum power demand.

I don't think anybody is suggesting that. Certainly not myself.

I am.

I'll quote the relevant regulations again:

C5.12 Power unit torque or power demand
C5.12.1 At any given engine speed the driver torque demand map must be monotonically increasing for an increase in accelerator pedal position.
C5.12.2 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.
C5.12.3 At any given engine speed, the minimum torque in the driver torque demand map must be a negative value greater than the minimum curve defined as Torque (Nm) = −0.0027 * engine speed (rpm) − 30.
C5.12.4 Except for conforming to Article C5.2.8, the driver maximum power demand cannot be reduced by more than 150kW at the start of any full Throttle period and the power reduction will remain fixed for a minimum of 1s.
C5.12.5 The driver maximum power demand cannot be increased during any full Throttle period, except when the overtake mode, as specified in the Appendix to the Regulations, is selected by the driver.
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.
C5.12.f The electrical DC power of the ERS‐K may not be reduced at rates greater than those specified in Article C5.12.6, unless:
• the theoretical MGUK power resulting from reduction at rates equal to those specified in Article C5.12.6 is negative;
• the ICE power is negative and the ERS-K power needs to be reduced further to achieve the driver demand;
• the ERS-K power needs to be reduced further to achieve the maximum power permitted by Article C5. 2.8;
• the driver power demand is negative;
• a gearshift is in progress.
• car speed is below 210kph.
C5.12.8 Details of the implementation in the FIA Standard ECU of the application and monitoring of Article C5.12 may be found in the document FIA-F1-DOC-Cxxx.

[diffuser]

. . . . NO, the regulations do not allow energy recovery under driver maximum power demand.

I don't think anybody is suggesting that. Certainly not myself.

I am.

I'll quote the relevant regulations again:

C5.12 Power unit torque or power demand
C5.12.1 At any given engine speed the driver torque demand map must be monotonically increasing for an increase in accelerator pedal position.
C5.12.2 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.
C5.12.3 At any given engine speed, the minimum torque in the driver torque demand map must be a negative value greater than the minimum curve defined as Torque (Nm) = −0.0027 * engine speed (rpm) − 30.
C5.12.4 Except for conforming to Article C5.2.8, the driver maximum power demand cannot be reduced by more than 150kW at the start of any full Throttle period and the power reduction will remain fixed for a minimum of 1s.
C5.12.5 The driver maximum power demand cannot be increased during any full Throttle period, except when the overtake mode, as specified in the Appendix to the Regulations, is selected by the driver.
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.
C5.12.f The electrical DC power of the ERS‐K may not be reduced at rates greater than those specified in Article C5.12.6, unless:
• the theoretical MGUK power resulting from reduction at rates equal to those specified in Article C5.12.6 is negative;
• the ICE power is negative and the ERS-K power needs to be reduced further to achieve the driver demand;
• the ERS-K power needs to be reduced further to achieve the maximum power permitted by Article C5. 2.8;
• the driver power demand is negative;
• a gearshift is in progress.
• car speed is below 210kph.
C5.12.8 Details of the implementation in the FIA Standard ECU of the application and monitoring of Article C5.12 may be found in the document FIA-F1-DOC-Cxxx.

The "driver maximum power demand" sound incorrectly stated. You'd think that means both the ICE plus MGU-K sending max power to the transmission. The MGU-K can't charge the battery and apply HP to the crankshaft at tge same time? At best you can do is send all the ICE power minus whatever you use for charging.

[wuzak]

I don't think anybody is suggesting that. Certainly not myself.

I am.

I'll quote the relevant regulations again:

C5.12 Power unit torque or power demand
C5.12.1 At any given engine speed the driver torque demand map must be monotonically increasing for an increase in accelerator pedal position.
C5.12.2 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.
C5.12.3 At any given engine speed, the minimum torque in the driver torque demand map must be a negative value greater than the minimum curve defined as Torque (Nm) = −0.0027 * engine speed (rpm) − 30.
C5.12.4 Except for conforming to Article C5.2.8, the driver maximum power demand cannot be reduced by more than 150kW at the start of any full Throttle period and the power reduction will remain fixed for a minimum of 1s.
C5.12.5 The driver maximum power demand cannot be increased during any full Throttle period, except when the overtake mode, as specified in the Appendix to the Regulations, is selected by the driver.
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.
C5.12.f The electrical DC power of the ERS‐K may not be reduced at rates greater than those specified in Article C5.12.6, unless:
• the theoretical MGUK power resulting from reduction at rates equal to those specified in Article C5.12.6 is negative;
• the ICE power is negative and the ERS-K power needs to be reduced further to achieve the driver demand;
• the ERS-K power needs to be reduced further to achieve the maximum power permitted by Article C5. 2.8;
• the driver power demand is negative;
• a gearshift is in progress.
• car speed is below 210kph.
C5.12.8 Details of the implementation in the FIA Standard ECU of the application and monitoring of Article C5.12 may be found in the document FIA-F1-DOC-Cxxx.

The "driver maximum power demand" sound incorrectly stated. You'd think that means both the ICE plus MGU-K sending max power to the transmission. The MGU-K can't charge the battery and apply HP to the crankshaft at tge same time? At best you can do is send all the ICE power minus whatever you use for charging.

Driver maximum power demand is where the driver has his accelerator pedal to the floor, demanding the maximum output from the PU.

The rules above define the reduction of MGUK output when at full throttle so that the MGUK power doesn't just cut off. Other rules specify maximum MGUK vs speed.

At 345km/h the MGUK reduces to 0kW. At the end of the full throttle section, they can start harvesting, up to 250kW recovery.

[wuzak]

Consider 4 seconds of full deployment. Seconds 1-4 you have 1030 HP (more than we have now), second 5 you have 965 HP, second 6 you have 900 HP, second 7 you have 835 HP, second 8 you have 770 HP, etc. With the low drag mode and the lighter car you will accelerate plenty with these numbers, even when tapering those first few seconds.

Come to think of it 4 seconds of full deployment may be too much. 3 seconds may be more appropriate for a long straight. Especially when you consider that you will be traction limited early in the acceleration phase so you won't need full beans the first second probably.

6s acceleration from 70km/h to 290km/h is a 220km/h increase.

4s acceleration would give you a bit more than 220*4/6 = 147km/h increase.

After 4s the speed would be 217km/h+.

But we know the acceleration is not constant, so it will probably be 240-250km/h, still a deficit of 50-40km/h.

It's going to take longer to get to 290km/h than 6s using lower power to accelerate, and the speed vs distance will be lower all along the straight.

We do not know what the current PUs produce, other than it is about 1,000hp. Which is similar to next year.

Assume 400kW for the ICE (often stated target, 48% TE).

First 4s total power 750kW, MGUK deployment 350kW = 1,400kJ

Your ramp rate seems to be 50kW/s, so 7s ramping to get to 0kW deployment.

7 * 350 / 2 = 1,225kJ.

Total energy deployed = 2,625kJ.

But you've deployed for 11s out of 23s. What do you do for the next 12s?

After 6s your scenario would have 100kW less power than my scenario. At 11s it would still be 100kW less, after 12s 50kW less and equal at 13s.

That is a big disadvantage in acceleration and speed along the straight.

Obviously. You deploy more energy on one straight you will go faster there, what about the rest of the lap? I'm suggesting the fastest way around the lap will be to mete out the deployment more evenly across several acceleration zones, especially on a track like Spa where you have more than one long straight.

For Spa, the second long section starts at either Fagnes or Stavelot (I'm not sure if Stavelot is flat or will be flat).

Exit of Fagnes is ~175km/h, Stavelot 295km/h.

So the time at maximum MGUK output will be much less than from La Source to Les Combes.

The slowest corners are T1 (La Source) and T18 (first Bus Stop corner).

[saviour stivala]

. . . . NO, the regulations do not allow energy recovery under driver maximum power demand.

I don't think anybody is suggesting that. Certainly not myself. What I am saying is - "Under reduced driver power demand - it is permitted for the control system to operate the ICE at higher output than demanded and send the surplus energy to the ES via the MGUK" The following quote from the Tech Regs makes it clear that energy can be harvested under braking AND AT PARTIAL LOAD.

https://i.imgur.com/76bx5CM.png
.
The regs go on to specify the limits for Partial Load Harvesting.
https://i.imgur.com/rpqNu90.png
.
The following table illustrates a few examples of partial load harvesting limits using the formula above.
https://i.imgur.com/wMG6lTY.png
.
There is no requirement in the regulations for the brake pedal to be used to initiate Partial Load Harvesting. The teams would be free to do so, but in most cases the degree and frequency of Partial Load Harvesting will be determined by the control system in accordance with the mode setting selected by the driver - not the brake pedal.

''No, The regulations do not allow energy recovery under driver maximum power demand'', sometimes also expressed as ''while or when'', driver is at full throttle''. Because 'you' did not think anybody is suggesting 'that', it doesn't mean that nobody did, in fact it wasn't long before you had an answer to that from direct from the horse mouth. Anyhow, I don't recone having attributed the above quote to you. As regards the rest you added in your post, What I was saying was, ''CORNERING HARVESTING/HARVESTING IN CORNERS WITH INCREASED ENGINE REVS: During cornering, even when the driver lifts of throttle or lightly brakes, the MGU-K will be used to slow the engine's rotation, which is what forces the MGU-K to generate power, to make the MGU-K work, specific engine maps will cause the engine to increase its revolutions per minute (rpm), even if driver isn't demanding it.

[gruntguru]

. . . . NO, the regulations do not allow energy recovery under driver maximum power demand.

I don't think anybody is suggesting that. Certainly not myself.

I am.

You are absolutely correct - thanks Wuzak.
Furthermore, the regulation you quoted makes it crystal clear that harvesting can be initiated by the control system without any additional input from the driver (eg brake pedal).

[saviour stivala]

I don't think anybody is suggesting that. Certainly not myself.

I am.

You are absolutely correct - thanks Wuzak.
Furthermore, the regulation you quoted makes it crystal clear that harvesting can be initiated by the control system without any additional input from the driver (eg brake pedal).

NO, Energy harvesting by MGU-K IN 2026 will 'not' be initiated by the driver 'not' using the brake pedal. The MGU-K recovers energy from the car's kinetic energy during braking and will be the sole method for energy recovery after the MGU-H is removed. New regulations allow for MGU-K to recover energy during cornering as well, which is a change from previous years, but the primary and most powerful energy recovery method will remain braking.

[wuzak]

For reference, the other regulation that is cited by C.5.12 is:

C5.2.8 Additionally, and subject to Article B7.2.1, the electrical DC power of the ERS-K used to propel the car may not exceed:
i. P(kW) = 1800 – 5 * car speed (kph) when the car speed is below 340kph
P(kW) = 6900 – 20 * car speed (kph) when the car speed is equal to or above 340kph and below 345kph
P(kW) = 0 when the car speed is equal to or above 345kph
ii. In Override Mode up to:
P(kW) = 7100 – 20 * car speed (kph) when the car speed is below 355kph
P(kW) = 0 when the car speed is equal to or above 355kph.

[michl420]

I am.

You are absolutely correct - thanks Wuzak.
Furthermore, the regulation you quoted makes it crystal clear that harvesting can be initiated by the control system without any additional input from the driver (eg brake pedal).

NO, Energy harvesting by MGU-K IN 2026 will 'not' be initiated by the driver 'not' using the brake pedal. The MGU-K recovers energy from the car's kinetic energy during braking and will be the sole method for energy recovery after the MGU-H is removed. New regulations allow for MGU-K to recover energy during cornering as well, which is a change from previous years, but the primary and most powerful energy recovery method will remain braking.

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.

This is the regulation, it states quite clearly, that the MGUK power CAN reduced to -250 KW. This is energy harvesting under full trottle. It can not be more clear.
Please stop claiming the opposite.