2025/2026 Hybrid Powerunit speculation

[djos]

I’d love To see them change to the simpler system Porsche used on the 919 which simply harvests exhaust gas energy without the complexity of electrically spinning up the turbo.

So how does it harvest (and store?) then?

It’s just a simple turbine connected directly to a generator.

[Stu]

The only way that I can see them being able to use 350kW (using only the rear axle) for any significant period of time is to operate the drivetrain as a series hybrid with parallel KERS. Utilising the ICE/motor drive as a generator when ‘off-throttle’.

Uh, what? Both series and parallel? The K sits on the crankshaft and can be used in parallel to both generate and to provide power.
By off throttle you mean during braking? Yeah, I wouldn't be surprised to hear screaming engines in some of the slowest turns.

I would imagine that removal of the MGUH would lead to lower ICE performance (and efficiency) as they are currently utilising this to fill ‘gaps’ in the power curve, which would lead to terrible power delivery and drivability. A series hybrid solution would allow for this.

Definitely efficiency, the K could compensate for power, but why would you call it "series"?

I would define a series hybrid as one that can alternate between charge/operate the drive motor-generator in series with the ICE, a parallel system is either charging OR operating (KERS/MGU-K) is a parallel drive system, as it is charged only during braking.
The current MGU-H almost operates as a series drive for the ICE, but is only indirectly connected to the drivetrain, a ‘full’ series drive would see the motor/ICE directly connected (much like it is/was in the Honda CRV); the gearbox is driven by both simultaneously (it also allows for periods of electric-only drive by switching the ICE ‘off’ - could be a very useful pit-lane/VSC device?) and the motor-generator would essentially used in place of the clutch. Quite how viable this would be, I’m not certain, but I see little difference between this and how hub-drive motors are required to work.

[NL_Fer]

Another option would be a complex gearbox, connecting one or two MGU’s to the driveline in different ratio’s. Like Renault already has on the Clio and Captur E-Tech Hybrids.

This could also help with keeping up the breaking recovery at maximum, during deceleration.

[Tommy Cookers]

... The K sits on the crankshaft and can be used in parallel to both generate and to provide power.
.... I wouldn't be surprised to hear screaming engines in some of the slowest turns.

the engine can't scream by an unusual amount
the K has a fixed link to the crankshaft and the crankshaft is linked to the rear axle by the 8 gears
isn't the ratio between 1st and 8th less than 2 ? (well less than 2 since they use eg 1st - 7th or eg 2nd - 8th)
in slowest turns the crankshaft rpm will be c.5000

burning fuel to generate is (best) done at high rpm ie throughout downshift sequences that prolong 10500 duration
cos high rpm gives more kW - ie full voltage and preferred torque/current
part rpm gives less kW - ie part voltage and preferred current
though the rules allow torque/current to increase above that preferred as rpm falls torque is capped at c. 6200 rpm
everybody seems to go the 10500 prolongation route (staying at preferred current)

the 8 speed gearbox is doing a big favour for the electrical side

[mzso]

I would define a series hybrid as one that can alternate between charge/operate the drive motor-generator in series with the ICE, a parallel system is either charging OR operating (KERS/MGU-K) is a parallel drive system, as it is charged only during braking.
The current MGU-H almost operates as a series drive for the ICE, but is only indirectly connected to the drivetrain, a ‘full’ series drive would see the motor/ICE directly connected (much like it is/was in the Honda CRV); the gearbox is driven by both simultaneously (it also allows for periods of electric-only drive by switching the ICE ‘off’ - could be a very useful pit-lane/VSC device?) and the motor-generator would essentially used in place of the clutch. Quite how viable this would be, I’m not certain, but I see little difference between this and how hub-drive motors are required to work.

In normal usage series hybrid means that the ICE provides no traction only generates energy for the electric motor. A parallel hybrid is when both the electric motor and the ICE drive the wheels.

[mzso]

... The K sits on the crankshaft and can be used in parallel to both generate and to provide power.
.... I wouldn't be surprised to hear screaming engines in some of the slowest turns.

the engine can't scream by an unusual amount
the K has a fixed link to the crankshaft and the crankshaft is linked to the rear axle by the 8 gears
isn't the ratio between 1st and 8th less than 2 ? (well less than 2 since they use eg 1st - 7th or eg 2nd - 8th)
in slowest turns the crankshaft rpm will be c.5000

burning fuel to generate is (best) done at high rpm ie throughout downshift sequences that prolong 10500 duration
cos high rpm gives more kW - ie full voltage and preferred torque/current
part rpm gives less kW - ie part voltage and preferred current
though the rules allow torque/current to increase above that preferred as rpm falls torque is capped at c. 6200 rpm
everybody seems to go the 10500 prolongation route (staying at preferred current)

the 8 speed gearbox is doing a big favour for the electrical side

It could if the clutch is disengaged.
But I guess it could also generate any time (any turn) full ICE power cannot be used, sort-of braking the engine. Tuning this would be a bitch I guess.

Aren't downshift sequences a tad too short for significant power generation?

[Zynerji]

... The K sits on the crankshaft and can be used in parallel to both generate and to provide power.
.... I wouldn't be surprised to hear screaming engines in some of the slowest turns.

the engine can't scream by an unusual amount
the K has a fixed link to the crankshaft and the crankshaft is linked to the rear axle by the 8 gears
isn't the ratio between 1st and 8th less than 2 ? (well less than 2 since they use eg 1st - 7th or eg 2nd - 8th)
in slowest turns the crankshaft rpm will be c.5000

burning fuel to generate is (best) done at high rpm ie throughout downshift sequences that prolong 10500 duration
cos high rpm gives more kW - ie full voltage and preferred torque/current
part rpm gives less kW - ie part voltage and preferred current
though the rules allow torque/current to increase above that preferred as rpm falls torque is capped at c. 6200 rpm
everybody seems to go the 10500 prolongation route (staying at preferred current)

the 8 speed gearbox is doing a big favour for the electrical side

It could if the clutch is disengaged.
But I guess it could also generate any time (any turn) full ICE power cannot be used, sort-of braking the engine. Tuning this would be a bitch I guess.

Aren't downshift sequences a tad to short for significant power generation?

I wouldn't think so if there is a super capacitor bank in the battery. That could soak up lots of juice in very short order, then push it out into the batteries.

[mzso]

I wouldn't think so if there is a super capacitor bank in the battery. That could soak up lots of juice in very short order, then push it out into the batteries.

But wouldn't create more recoverable energy. The problem is the lack of energy to be used not storing it.

Also, dealing with the power so-far never has been an issue.

[Holm86]

Using the MGU-K as a generator to harvest directly from the ICE sound very inefficient?

I don't understand why they couldn't settle for a solution like Porsches from LMP, where they only had a generator, not a motor on the exhaust side, would be much simpler

[henry]

Using the MGU-K as a generator to harvest directly from the ICE sound very inefficient?

The fuel conversion efficiency (energy_to_road/energy_in_fuel) may be low but the lap time and race time effectiveness may be worthwhile since they can deploy higher power at lower road speed moving the car instead of moving the air.

[noname]

Using the MGU-K as a generator to harvest directly from the ICE sound very inefficient?

I don't understand why they couldn't settle for a solution like Porsches from LMP, where they only had a generator, not a motor on the exhaust side, would be much simpler

Packaging?

Porsche used 2 machines - turbocharger and turbogenerator. F1 has only one - electric turbocharger.

[Jolle]

Using the MGU-K as a generator to harvest directly from the ICE sound very inefficient?

I don't understand why they couldn't settle for a solution like Porsches from LMP, where they only had a generator, not a motor on the exhaust side, would be much simpler

Don’t forget the Porsche 919 was designed around the same time as the F1 hybrid systems and for a whole different race. Drivability is less an issue at Le Mans, so a bit of turbo lag is ok while reliability is much more important. With a separate turbine to harvest some heat back. You can also disconnect it when you blow a bearing.
Since then (these systems now have been races for 8 seasons), systems became a lot more reliable and even are making their way into road cars. AMG is already using a electric compressor in the 53 series and I thought a real MGU-H is coming to the new four in line series.

[noname]

(...) AMG is already using a electric compressor in the 53 series and I thought a real MGU-H is coming to the new four in line series.

Those electric compressors are also used by Audi (I guess even before Merc) i.e. in SQ7.
https://www.motorauthority.com/news/111 ... -turbo-lag

"MGU-H" AMG is plenning to use is just few-kW (around 5) 48V electric motor used to support compressor at low engine RPM. One can think of this as integrated version of the compressor presented above.

Although motor is integrated inside turbocharger, I consider calling it F1 technology as marketing BS. It is only boost support, no harvesting. And there is good reason why - in real-life condition energy recovery does not make (much) sense.

[basti313]

(...) AMG is already using a electric compressor in the 53 series and I thought a real MGU-H is coming to the new four in line series.

Those electric compressors are also used by Audi (I guess even before Merc) i.e. in SQ7.
https://www.motorauthority.com/news/111 ... -turbo-lag

"MGU-H" AMG is plenning to use is just few-kW (around 5) 48V electric motor used to support compressor at low engine RPM. One can think of this as integrated version of the compressor presented above.

Although motor is integrated inside turbocharger, I consider calling it F1 technology as marketing BS. It is only boost support, no harvesting. And there is good reason why - in real-life condition energy recovery does not make (much) sense.

Yes, generally it is highly inefficient to produce rotation and heat out of petrol, try to store this and then make rotation out of it again. The whole MGU-H thing is highly inefficient, it is just there as you need it for the rules in F1.
It is good that they drop it.

I also do not think you need to spin up the turbo with the H on an F1 car. Completely different usage on the road car.

[henry]

(...) AMG is already using a electric compressor in the 53 series and I thought a real MGU-H is coming to the new four in line series.

Those electric compressors are also used by Audi (I guess even before Merc) i.e. in SQ7.
https://www.motorauthority.com/news/111 ... -turbo-lag

"MGU-H" AMG is plenning to use is just few-kW (around 5) 48V electric motor used to support compressor at low engine RPM. One can think of this as integrated version of the compressor presented above.

Although motor is integrated inside turbocharger, I consider calling it F1 technology as marketing BS. It is only boost support, no harvesting. And there is good reason why - in real-life condition energy recovery does not make (much) sense.

Yes, generally it is highly inefficient to produce rotation and heat out of petrol, try to store this and then make rotation out of it again. The whole MGU-H thing is highly inefficient, it is just there as you need it for the rules in F1.
It is good that they drop it.

I also do not think you need to spin up the turbo with the H on an F1 car. Completely different usage on the road car.

The vast majority of the energy harvested by the MGU-H goes directly to the MGU-K. Only a small proportion is stored in the ES and then used by the MGU-K, and sometimes the MGU-H, mainly for use at low road speeds to enhance acceleration.

I’m not sure what definition of efficiency you’re using.