2025/2026 Hybrid Powerunit speculation

[Tommy Cookers]

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

G-UK action when the ICE would otherwise be throttled increases efficiency
this is used in all those hybrids

there is no fundamental difference between eg a GU-H only machine and an MGU-H machine
your car's alternator can act as a motor but it's blocked from acting as a motor
your car's starter motor can act as a generator but it's blocked from acting as a generator

yes there might be a cooling benefit realisable from using a machine as M-only or G-only

[basti313]

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.

Whatever is recovered on the H is in the first place generated by air and petrol quite inefficiently in the ICE. On a "normal" modern engine the turbo would simply have less backpressure ending in less fuel spend to rotate the engine. I did not think to much on this so far, but there must be some weirdness in the energy flow mandated by the rules, which makes it good to waste extra fuel on some percent hot air to generate extra horsepower in the K.

[Tommy Cookers]

Whatever is recovered on the H is in the first place generated by air and petrol quite inefficiently in the ICE. On a "normal" modern engine the turbo would simply have less backpressure ending in less fuel spend to rotate the engine...

the ICE has unusual 50% efficiecy as unusually little heat needs removal by coolant - leaving more heat turned into work
because there is an unusually high air massflow combustion heat is unusually diluted ie cylinder gas is cooler pre-coolant
unusually high massflow comes from unusually high boost pressure - & backpressure is counteracted by forward pressure
unusual heat dilution is enabled by the novel injection/ignition process that emulates a pre-chamber

H recovery is a further benefit - at the pressure ratio of 3 or 4 it's quite substantial (and uses any late combustion)
and anyway some wave/pulse KE recovery exists independent of apparent exhaust pressure

[Rodak]

Racefans F1 has a post up that Audi are coming to F1. I assume as an engine manufacturer.......

https://www.racefans.net/

[gruntguru]

Whatever is recovered on the H is in the first place generated by air and petrol quite inefficiently in the ICE. On a "normal" modern engine the turbo would simply have less backpressure ending in less fuel spend to rotate the engine.

An efficient exhaust recovery turbine mostly harvests heat energy that would be otherwise wasted. When high PR is used causing extra pumping work on the exhaust stroke, this work will be recovered as useful pumping work on the intake stroke.

The nett effect is - a highly turbocharged gasolene engine with exhaust manifolding designed to recover blowdown energy, and operating lean of stoichiometric can be significantly more fuel efficient than NA.

Read up on the Wright Turbo Compound. http://www.enginehistory.org/Piston/Wri ... CFacts.pdf

[Stu]

Racefans F1 has a post up that Audi are coming to F1. I assume as an engine manufacturer.......

https://www.racefans.net/

The big rumour is that VW will be entering with Porsche as an engine manufacturer AND one of the Audi-group as a constructor. The Audi-McLaren deal got leaked (and then semi-denied by McLaren - the wording was strange!!); could be a plan to use Bentley, Lamborghini or Bugatti rather than the Audi brand. That way they get multiple names on the board. My guess would be Porsche engines for Williams….
Of course, McLaren once used Porsche engines badged as TAG back in the mid-eighties.

A fifth engine manufacturer would be good for F1, but would Renault step up and supply a second team? Who would it be - Sauber?

[mzso]

May be a stupid question, but can't energy be recovered from the exhaust directly, meaning mechanically. Instead of going to electric generators and batteries.

[Tommy Cookers]

.... can't energy be recovered from the exhaust directly, meaning mechanically. Instead of going to electric generators and batteries.

a mechanical routeing of exhaust recovery isn't allowed

also not allowed for KE recovery
also not allowed for energy storage

[mzso]

.... can't energy be recovered from the exhaust directly, meaning mechanically. Instead of going to electric generators and batteries.

a mechanical routeing of exhaust recovery isn't allowed

also not allowed for KE recovery
also not allowed for energy storage

I meant practically. They'll change the regulations to whatever they want.

[henry]

May be a stupid question, but can't energy be recovered from the exhaust directly, meaning mechanically. Instead of going to electric generators and batteries.

It could be. The Wright engine often referenced did just that.

It would probably be lighter and less complex. It might need a cunning transmission.

You would lose the ability to burn fuel at high speed to be used at low.

[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

G-UK action when the ICE would otherwise be throttled increases efficiency
this is used in all those hybrids

there is no fundamental difference between eg a GU-H only machine and an MGU-H machine
your car's alternator can act as a motor but it's blocked from acting as a motor
your car's starter motor can act as a generator but it's blocked from acting as a generator

yes there might be a cooling benefit realisable from using a machine as M-only or G-only

How is it efficient to take the energy from the fueltank, rund it through the engine at around 40% thermal efficiency, and then further down the MGU-K into the battery?? That means the energy content from the fuel will only be at around 39-38% when it makes it to the battery.

I know that having at MGU-H and a GU-H mechanically would be more or less the same, what im thinking about is you dont have to think about the the deployment of the MU-H which is one of the complicated things about it that made VAG wanting to get rid of it in the first place.
What im sayin is inbetween getting completly rid of the MGU-H, and keeping it, could be a compromise of just allowing harvesting energy, and not deploying it.

[Stu]

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

G-UK action when the ICE would otherwise be throttled increases efficiency
this is used in all those hybrids

there is no fundamental difference between eg a GU-H only machine and an MGU-H machine
your car's alternator can act as a motor but it's blocked from acting as a motor
your car's starter motor can act as a generator but it's blocked from acting as a generator

yes there might be a cooling benefit realisable from using a machine as M-only or G-only

How is it efficient to take the energy from the fueltank, rund it through the engine at around 40% thermal efficiency, and then further down the MGU-K into the battery?? That means the energy content from the fuel will only be at around 39-38% when it makes it to the battery.

I know that having at MGU-H and a GU-H mechanically would be more or less the same, what im thinking about is you dont have to think about the the deployment of the MU-H which is one of the complicated things about it that made VAG wanting to get rid of it in the first place.
What im sayin is inbetween getting completly rid of the MGU-H, and keeping it, could be a compromise of just allowing harvesting energy, and not deploying it.

I’m not sure how they are going to get 350kW/h of harvesting if they don’t, that’s an awful lot of lift & coast!!

[mzso]

How is it efficient to take the energy from the fueltank, rund it through the engine at around 40% thermal efficiency, and then further down the MGU-K into the battery?? That means the energy content from the fuel will only be at around 39-38% when it makes it to the battery.

I guess it could harvest when the engine is at it's peak efficiency (which I think is 50%+ not 40%) and used in circumstances when it needs to (or would need to) work at its lowest efficiency.

If not then it would be just an even more hollowly "green" technology.

[gruntguru]

Even if the peak TE of the ICE is only 50%, the "real" efficiency of ICE->MGUK harvesting can be even higher. When engine demand is low (mid-corner, brakiing, or otherwise traction limited) and this operating condition is a long way from peak thermal efficiency, an additional load applied by the MGUK could bring the ICE closer to peak TE, meaning the added load is satisfied at an "incremental" efficiency much higher than 50%.

[mzso]

It could be. The Wright engine often referenced did just that.

What engine do you mean by that. I think the Wright company produced several engines.

It would probably be lighter and less complex. It might need a cunning transmission.

Sounds interesting.

You would lose the ability to burn fuel at high speed to be used at low.

I guess they sort of could do that if they also use the K to harvest at the same time.
At least that's how it seems to me.