2025/2026 Hybrid Powerunit speculation

[wuzak]

MGU-K energy recovery during cornering in 2026 against an increased ICE revs will require the driver to also lightly brake, in short the brake pedal will have to be used. The increased ICE revs will be allowed to happen even if driver lifts off throttle by special maps.

Where do you get the idea that the driver has to brake to get energy recovery?

We have shown you regulations that allow recovery under driver maximum power demand and how the fuel flow changes for part throttle, but you have yet to cite a regulation that requires the driver to brake to initiate energy recovery.

The mechanical brakes are still hydraulically linked to the brake pedal, or at least the fronts are. So any "light braking" will also activate them, and reduce the amount of energy that can be recovered.

The ICE fuel flow follows the same outline as the current regulations, with the peak fuel flow occurring at 10,500rpm and maximum speed of 15,000rpm.

Why would the PU have "increased ICE revs"?

Unless they've somehow made it more conducive to rev higher, the power band will, likely, be similar to today - from ~10,000 to ~13,000 rpm.

[gruntguru]

''Time to put an end to this nonsense'' Far from it. The 2026 formula 1 regulations depicts a bidirectional energy flow arrow between the ICE and MGU-K through a newly simplified power unit that removes the MGU-H. The MGU-K will now have a dual function: It harvests kinetic energy from braking to store in battery, and it can also receive energy from the ICE to deliver power to the drivetrain, creating a more interconnected system.

Firstly - There is no need for the MGU-K to "receive energy from the ICE to deliver power to the powertrain" - power can be sent directly from the ICE to the wheels as it has for over 100 years.

Secondly - did you read and understand points 2. and 3. in my post? What is your explanation for the regulations allowing enough fuel for maximum ICE output, when the driver is only at part throttle - requesting only 218 KW to the wheels?

[wuzak]

Secondly - did you read and understand points 2. and 3. in my post? What is your explanation for the regulations allowing enough fuel for maximum ICE output, when the driver is only at part throttle - requesting only 218 KW to the wheels?

Maybe that's where "extra rpm" comes from?

In order to maximise energy recovery, they may use a lower gear than currently, so that the maximum fuel flow can be accessed, rather than the fuel flow restricted by rpm.

[gruntguru]

I have to ask, if the limit of energy recovery per lap is 8.5MJ . . . .
. . . . Albert Park: ~8.5s braking, 2,975KJ possible recovery (ie not even 3/4 of the battery capacity)
Red Bull Ring: ~8.6s braking, 3,010KJ possible recovery (just 3/4 of the battery capacity)
Monza: 9.25s braking, 3,237kJ (ie just over 3/4 of the battery capacity)
Silverstone: ~11s braking, 3,850kJ - still haven't filled the battery
Jeddah: ~11s braking, 3,850kJ - still haven't filled the battery
Singapore: ~17s, 5,950kJ (can fill the battery 1.5 times, but still not teh maximum 8.5MJ)
Monaco: ~19s, 6,650kJ (getting closer)
Baku: ~19s, 6,650kJ (7 of the braking events are classified as hard, 2 medium, 3 light)

Not sure where you slipped up here Wuzak but:
2,975 KJ = 2.975 MJ - about 1/3 of the permitted 8.5 MJ.
etc

[gruntguru]

Secondly - did you read and understand points 2. and 3. in my post? What is your explanation for the regulations allowing enough fuel for maximum ICE output, when the driver is only at part throttle - requesting only 218 KW to the wheels?

Maybe that's where "extra rpm" comes from?

In order to maximise energy recovery, they may use a lower gear than currently, so that the maximum fuel flow can be accessed, rather than the fuel flow restricted by rpm.

Yes, if they need to maximise harvest, we will hear them at 10,500 rpm or higher in corners.

[Badger]

I have to ask, if the limit of energy recovery per lap is 8.5MJ . . . .
. . . . Albert Park: ~8.5s braking, 2,975KJ possible recovery (ie not even 3/4 of the battery capacity)
Red Bull Ring: ~8.6s braking, 3,010KJ possible recovery (just 3/4 of the battery capacity)
Monza: 9.25s braking, 3,237kJ (ie just over 3/4 of the battery capacity)
Silverstone: ~11s braking, 3,850kJ - still haven't filled the battery
Jeddah: ~11s braking, 3,850kJ - still haven't filled the battery
Singapore: ~17s, 5,950kJ (can fill the battery 1.5 times, but still not teh maximum 8.5MJ)
Monaco: ~19s, 6,650kJ (getting closer)
Baku: ~19s, 6,650kJ (7 of the braking events are classified as hard, 2 medium, 3 light)

Not sure where you slipped up here Wuzak but:
2,975 KJ = 2.975 MJ - about 1/3 of the permitted 8.5 MJ.
etc

He states “battery capacity”, ie 4 MJ.

[wuzak]

I have to ask, if the limit of energy recovery per lap is 8.5MJ . . . .
. . . . Albert Park: ~8.5s braking, 2,975KJ possible recovery (ie not even 3/4 of the battery capacity)
Red Bull Ring: ~8.6s braking, 3,010KJ possible recovery (just 3/4 of the battery capacity)
Monza: 9.25s braking, 3,237kJ (ie just over 3/4 of the battery capacity)
Silverstone: ~11s braking, 3,850kJ - still haven't filled the battery
Jeddah: ~11s braking, 3,850kJ - still haven't filled the battery
Singapore: ~17s, 5,950kJ (can fill the battery 1.5 times, but still not teh maximum 8.5MJ)
Monaco: ~19s, 6,650kJ (getting closer)
Baku: ~19s, 6,650kJ (7 of the braking events are classified as hard, 2 medium, 3 light)

Not sure where you slipped up here Wuzak but:
2,975 KJ = 2.975 MJ - about 1/3 of the permitted 8.5 MJ.
etc

He states “battery capacity”, ie 4 MJ.

Yes, battery capacity.

Battery capacity will be a limiting factor for tracks with long straights.

Some of those tracks also have trouble with braking energy recovery.

[Badger]

Not sure where you slipped up here Wuzak but:
2,975 KJ = 2.975 MJ - about 1/3 of the permitted 8.5 MJ.
etc

He states “battery capacity”, ie 4 MJ.

Yes, battery capacity.

Battery capacity will be a limiting factor for tracks with long straights.

Some of those tracks also have trouble with braking energy recovery.

Yeah but they won't be using much full deployment. I'll put my MS paint skills to the test and show how I think it will work.

Basically you'll need to balance the area under the curve across the lap so that it is plus-minus zero. As long as your state of charge max "delta" doesn't exceed 4 MJ across the lap, the battery capacity shouldn't be a limiting factor.

[wuzak]

There are a couple of tracks with full throttle sections exceeding 20s, and as high as 26s.

Those will be marginal with 4MJ battery.

The run from La Source to Les Combes is about 23s.

La Source is aroun 60-70km/h, which means there is a lot of speed to gain before the mandated ramping down.

It would take approximately 6s to accelerate from La Source at 70km/h to 290km/h, which is just above half the battery capacity used at maximum MGUK power. And there is 17s of the "straight" to go.

Also I believe that Spa will have a slower ramp down rate of 50kW.

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.

I'm not sure if this means they will use less energy on the full throttle run.

[wuzak]

Thinking a bit more about Spa.

6s @ 350kW from La Source to 290km/h = 2,100kJ.

7s at maximum ramp down rate from 350kW to 0Kw = 1,225kJ.

Total expended, 3,325kJ in 13s.

10s to go before braking for Les Combes.

5s to reduce from 0kW to -250kW at maximum ramp down rate = 625kJ recovered.

Braking time - approximately 1.6s = 560kJ recovered.

Net usage = approximately 2,700kJ from La Source to Braking for Les Combes.

If a less aggressive ramp down rate is used:
6s @ 350kW = 2,100kJ.
350kW to -250kW in 17s = ramp down rate of 600/17 = 35kW/s.

9.92s to go from 350kW to 0kW = 1,735kJ used.
7.08s to go from 0kW to -250kW = 885kJ recovered.

Net usage = 2,950kJ from La Source to Braking for Les Combes.

That all depends on how quickly they acelerate at speeds above 290km/h. 35kW/s may not be possible.

[vorticism]

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)

[wuzak]

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?

[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.

[vorticism]

The active aero will have an effect. In 'Straight-Line Mode' with less aero drag the harvesting might be maintained with less modification to the typical braking zones/durations. Relatively higher downforce set-ups in the 'Corner Mode' should be desirable. We might see more DF & higher cornering speeds than typical in low and medium speed corners for the traditional low-drag/low-DF tracks, because they can shed the drag in the approved zones.

[wuzak]

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.