2025/2026 Hybrid Powerunit speculation

[saviour stivala]

When ICE is charging the battery via MGU on straights, it's doing so in a regime where it provides near constant output and this regime can be made quite efficient. On the other hand, when the car is accelerating ICE inefficiently generates huge amount of excess power - which is also effectively wasted no matter what. MGU provides acceleration a lot more efficiently and this is where massive harvesting on straights makes sense in a 50-50 ICE-MGU architecture. Is this a correct assumption.

I would say that this is a perfect description for the MGU-H operation currently in use, but not sure that it is for MGU-K.
Maybe I’m just not able to ‘see it’, but if the K MGU & ICE are connected before the clutch system any charging under acceleration will have a negative impact on performance (and is a time when you expect the MGU to be in output mode).
I can ‘see’ that a new version of ‘clipping’ will be possible once the required speed is achieved on any straight, prior to the braking event (something similar in effect to lift & coast, but systematically induced).

Yes. "THIS" is a perfect description for the MGU-H (present system) but certainly not for the for the MGU-K. MGU-K (present system) only generates electricity (charge ES) under braking.

[wuzak]

When ICE is charging the battery via MGU on straights, it's doing so in a regime where it provides near constant output and this regime can be made quite efficient. On the other hand, when the car is accelerating ICE inefficiently generates huge amount of excess power - which is also effectively wasted no matter what. MGU provides acceleration a lot more efficiently and this is where massive harvesting on straights makes sense in a 50-50 ICE-MGU architecture. Is this a correct assumption.

I would say that this is a perfect description for the MGU-H operation currently in use, but not sure that it is for MGU-K.
Maybe I’m just not able to ‘see it’, but if the K MGU & ICE are connected before the clutch system any charging under acceleration will have a negative impact on performance (and is a time when you expect the MGU to be in output mode).
I can ‘see’ that a new version of ‘clipping’ will be possible once the required speed is achieved on any straight, prior to the braking event (something similar in effect to lift & coast, but systematically induced).

Yes. "THIS" is a perfect description for the MGU-H (present system) but certainly not for the for the MGU-K. MGU-K (present system) only generates electricity (charge ES) under braking.

According to you.

[saviour stivala]

Of course it is according to me. Yes. as that is the way I believe it is.

[gruntguru]

''When driving only needs partial ICE power 'running the engine against the MGU saves fuel because at partial ICE power (however) the ICE is less efficient''. When driving only needs partial power running the engine against the MGU or any other power consumer for that matter, will result in burning more fuel and not less.

Would challenge you to do some research on this. It is the core concept that hybrid vehicles are built around. Specifically look at a brake specific fuel consumption chart (BSFC). Ideally, hybrids are first meant to harvest the excess energy to keep the engine at optimum BSFC and then turn the engine off at any other operating location and run on the harvested energy outside of that.

When running the engine against the MGU under braking the fuel consumption goes up. (burning fuel to charge ES).

Fuel consumption is not fuel efficiency. The ICE will have its highest efficiency at somewhere near full load. Any charging of the ES should be done at the highest possible ICE efficiency to ensure each kg of fuel is converted to the maximum MJ at the tyre over the course of the race.

As you have said earlier, there is 70 kg of fuel (approximately 45 x 70 = 3150 MJ of heat energy) available during the race. If the engine is run at maximum efficiency (probably less than 50%) at all times, there will about 3150 x 50% = 1,575 MJ available to propel the car (plus any braking regen). Any peroids operating at less than peak ICE efficiency will reduce the total race energy available at the tyres.

[gruntguru]

. . .
AMuS (Gruner) has quite recently written that the F1 cars use 30% of the fuel to generate electricity

No doubt he means 15%.
50% - waste heat
35% - power to drive wheels
15% - generate electricity

[saviour stivala]

. . .
AMuS (Gruner) has quite recently written that the F1 cars use 30% of the fuel to generate electricity

No doubt he means 15%.
50% - waste heat
35% - power to drive wheels
15% - generate electricity

As I said any fuel burned to generate electricity at present is done by the MGU-H/said electricity generated is generated by MGU-H only "capturing and making use of exhaust energy that would otherwise have gone to waste". AND also agree that it is done when/while the ICE is operating/running at its peak efficiency "producing the highest percentage of the potential energy in the fuel and delivering it to the crankshaft''. That 'electricity produced' is a plus to the 2mj maximum permitted per-lap that can be produced under braking by the MGU-K "capturing and making use of brake energy that could otherwise have gone to waste''. Of course all this is as the system is at present.

[Zynerji]

. . .
AMuS (Gruner) has quite recently written that the F1 cars use 30% of the fuel to generate electricity

No doubt he means 15%.
50% - waste heat
35% - power to drive wheels
15% - generate electricity

I could see a 35, 35, 30 if they figured out how to insulate the cylinder walls with turbulent air during combustion.

[gruntguru]

Of course it is according to me. Yes. as that is the way I believe it is.

Yet you concede that the 2026 rules will allow charging under part throttle. Have you identified a rule that:
a) prohibits part throttle MGUK charging in the current regulations and -
b) no longer exists in the 2026 regulations?

The arrogance of someone whose native language is not English, telling a group of technical English speakers they don't know how to interpret a set of rules written in English is jaw-dropping.

[saviour stivala]

So for someone who's native language is not English it marks him as arrogant on an English-speaking forum. Re-the currently allowed generation by MGU-K. From the very first introduction of the current hybrid power unit the principal aim was to capture braking energy that would otherwise goes to waste, and the rules even went along in setting a maximum limit per lap of the amount that could be captured.

[FW17]

Would challenge you to do some research on this. It is the core concept that hybrid vehicles are built around. Specifically look at a brake specific fuel consumption chart (BSFC). Ideally, hybrids are first meant to harvest the excess energy to keep the engine at optimum BSFC and then turn the engine off at any other operating location and run on the harvested energy outside of that.

When running the engine against the MGU under braking the fuel consumption goes up. (burning fuel to charge ES).

Fuel consumption is not fuel efficiency. The ICE will have its highest efficiency at somewhere near full load. Any charging of the ES should be done at the highest possible ICE efficiency to ensure each kg of fuel is converted to the maximum MJ at the tyre over the course of the race.

As you have said earlier, there is 70 kg of fuel (approximately 45 x 70 = 3150 MJ of heat energy) available during the race. If the engine is run at maximum efficiency (probably less than 50%) at all times, there will about 3150 x 50% = 1,575 MJ available to propel the car (plus any braking regen). Any peroids operating at less than peak ICE efficiency will reduce the total race energy available at the tyres.

Should the fuel weight be 70kgs?

Can it not be higher like 120 kgs? with lot lesser MJ per kg? More fuel/liquid into the cylinder is better than air, lower temperature and it should give a bigger bang.

[Tommy Cookers]

Should the fuel weight be 70kgs?
Can it not be higher like 120 kgs? with lot lesser MJ per kg? More fuel/liquid into the cylinder is better than air, lower temperature and it should give a bigger bang.

afaik ....

the concept (still) is (according Pat Symonds FIA technology chief) any 'carbon neutral' fuel....
and ie any fuel load (kg) is permitted but the load's heat value is limited to 3000 MJ

given we currently have compulsory 10% (by volume) bio-ethanol
a 2026 fuel could conceivably have a lot of such alcohol
so a need to permit a big fuel load (eg 3000 MJ of ethanol weighs 112.3 kg)

70 kg is the media's uninformed 'translation' of the concept for the reader's benefit
basically the teams expectations

[wuzak]

When running the engine against the MGU under braking the fuel consumption goes up. (burning fuel to charge ES).

Fuel consumption is not fuel efficiency. The ICE will have its highest efficiency at somewhere near full load. Any charging of the ES should be done at the highest possible ICE efficiency to ensure each kg of fuel is converted to the maximum MJ at the tyre over the course of the race.

As you have said earlier, there is 70 kg of fuel (approximately 45 x 70 = 3150 MJ of heat energy) available during the race. If the engine is run at maximum efficiency (probably less than 50%) at all times, there will about 3150 x 50% = 1,575 MJ available to propel the car (plus any braking regen). Any peroids operating at less than peak ICE efficiency will reduce the total race energy available at the tyres.

Should the fuel weight be 70kgs?

Can it not be higher like 120 kgs? with lot lesser MJ per kg? More fuel/liquid into the cylinder is better than air, lower temperature and it should give a bigger bang.

When the current rules were introduce, the fuel flow rate was 100kg/h and the race fuel allowance was 100kg.

If we use a similar metric, the 2026 rules have a fuel energy flow rate of 3000MJ/h.

The fuel energy density is to be between 38MJ/kg and 41MJ/kg.

For 38MJ/kg the fuel woudl be 78.9kg.
For 41MJ/kg the fuel woudl be 73.2kg.

But the fuel allowance could be higher than that, since it is expected that they will have to burn more fuel to get the most from the ERS.

Suggestions were that it would be 100kg, but I am sceptical that amount would be required.

[wuzak]

Of course it is according to me. Yes. as that is the way I believe it is.

Yet you concede that the 2026 rules will allow charging under part throttle. Have you identified a rule that:
a) prohibits part throttle MGUK charging in the current regulations and -
b) no longer exists in the 2026 regulations?

The arrogance of someone whose native language is not English, telling a group of technical English speakers they don't know how to interpret a set of rules written in English is jaw-dropping.

I think saviour stivala was using an early version of the regulations, not the one that was used in 2014, or the updated ones since.

Also, he referenced an interview with a RBPT engineer where he states that recovering energy under power was not allowed, though the RBPT engineer also admitted to being on the ICE side with little experience with the ERS and its calibration.

[saviour stivala]

What I was saying concerns the 2014 hybrid power unit design guidelines and principles that finally were agreed upon by all concerned and as they still stand to this day. Limiting myself to the MGU-K the statement read ''MGU-K - MOTOR GENERATOR KINETC to capture braking energy that would otherwise goes to waste'' Those were and still are the guiding design principles, plus to that the technical regulations states the maximum (2mj per lap) that the MGU-K is permitted to recover. And when there was a sniff about somebody doing 'extra' harvesting, the rule makers promptly clamped down on that.

[wuzak]

What I was saying concerns the 2014 hybrid power unit design guidelines and principles that finally were agreed upon by all concerned and as they still stand to this day.

Meaning the existing engine suppliers at the time (Ferrari, Mercedes, Renault) and prospective suppliers (VAG, Cosworth, etc.)?

Limiting myself to the MGU-K the statement read ''MGU-K - MOTOR GENERATOR KINETC to capture braking energy that would otherwise goes to waste''

That does not appear in the 2014 technical regulations, even those published in 2012.

Those were and still are the guiding design principles

But it isn't in the regulations, so it can't really be "the guiding design principles".

plus to that the technical regulations states the maximum (2mj per lap) that the MGU-K is permitted to recover. And when there was a sniff about somebody doing 'extra' harvesting, the rule makers promptly clamped down on that.

Most tracks do not allow the MGUK recover 2MJ under braking alone. They have to lift-and-coast, or use another method, to generate the 2MJ.

You may have noticed that there is a lot less lift-and-coasting these days.