2025/2026 Hybrid Powerunit speculation

[Stu]

The big items that parameter the ICE block are set in the regs (crank height, piston centres, v-angle, mass); design work would largely be focussed on structural integrity, getting the mass low and maximising ballast capacity).
Get that in the ball-park and performance comes from combustion efficiency and MGU-K/Battery efficiency.
Turbo will become almost a spec part (it is so closely defined).

[saviour stivala]

Yes. Combustion efficiency will always be the prime target of the ICE part of the power unit. The more so if less fuel use will be allowed.

[Tommy Cookers]

Yes. Combustion efficiency will always be the prime target of the ICE part of the power unit. The more so if less fuel use will be allowed.

not so
combustion efficiency is simply the % of the fuel charge that is burned eg c.95% for any engine type

the % of the fuel heat that is converted to work is called thermal efficiency
either indicated TE (in-cylinder measure) or brake TE (crankshaft measure)
in current F1 the ITE is c. 60% and the BTE is c. 50%

[johnny comelately]

Yes. Combustion efficiency will always be the prime target of the ICE part of the power unit. The more so if less fuel use will be allowed.

not so
combustion efficiency is simply the % of the fuel charge that is burned eg c.95% for any engine type

the % of that fuel-burned heat that is converted to work is called thermal efficiency
either indicated TE (in-cylinder measure) or brake TE (crankshaft measure)
in current F1 the ITE is c. 60% and the BTE is c. 50%

How do you go talking about religion Tommy
Hard to pin you down on anything?

[Juzh]

pasting this from 2026 aero thread as it seems more relevant in this topic

The Energy Store has a specified minimum weight of 35kg for 2026.

The current ES has a minimum weight of 31kg.

The extra is probably to handle the higher power flows.

The ES has the same restrictions as now - maximum 4MJ difference between maximum and minimum charge, though 9MJ can be recovered and unlimited energy deployed.

Ah, thanks, so better recovery is allowed. I like that, gives me even more hope for another good step with 2026 rules.

Still can only store 4MJ.

It's probably been debated already, but you know.. 110 pages is a bit much to go trough. here's my question.
Maybe I'm missing something but is there even a plausible scenario in which a theoretical maximum of 13 MJ can be used up in a lap? Seems completely impossible, and with the removal of the mgu-h component much of the complexity is removed from the equation.

Say you start with 4 MJ stored to start the lap, recovery from braking is additional ~2 MJ at most in best of cases, so unless extra recovery is coming from the already mentioned (and supposedly not allowed as per RBPT engineer) ICE to mgu-k at 100kw what's the purpose of having extra 9 MJ available. Seems like an unreasonable amount.

In fact even starting the lap at 4 MJ stored would be a challenge without this, as regs prohibit charging the battery in garage or pitstop in excess of 100 kj.
5.4.12 The amount of stored energy in any ES may not be increased by more than 100kJ whilst the car is stationary in the pit lane or garage during the Qualifying Session or during a Race pit stop.

Ok, it doesn't specifically say you can't charge in pitlane before qualifying. So you go out at ~8MJ, top up to 10MJ, then you can down to 6MJ after first quali lap. Recover ~1 MJ on inlap, another 2MJ on outlap for second lap, still you're nowhere near allowed recovery, and in fact are dropping total charge with each hotlap...?

[AR3-GP]

pasting this from 2026 aero thread as it seems more relevant in this topic

Ah, thanks, so better recovery is allowed. I like that, gives me even more hope for another good step with 2026 rules.

Still can only store 4MJ.

It's probably been debated already, but you know.. 110 pages is a bit much to go trough. here's my question.
Maybe I'm missing something but is there even a plausible scenario in which a theoretical maximum of 13 MJ can be used up in a lap? Seems completely impossible, and with the removal of the mgu-h component much of the complexity is removed from the equation.

Say you start with 4 MJ stored to start the lap, recovery from braking is additional ~2 MJ at most in best of cases, so unless extra recovery is coming from the already mentioned (and supposedly not allowed as per RBPT engineer) ICE to mgu-k at 100kw what's the purpose of having extra 9 MJ available. Seems like an unreasonable amount.

In fact even starting the lap at 4 MJ stored would be a challenge without this, as regs prohibit charging the battery in garage or pitstop in excess of 100 kj.
5.4.12 The amount of stored energy in any ES may not be increased by more than 100kJ whilst the car is stationary in the pit lane or garage during the Qualifying Session or during a Race pit stop.

Ok, it doesn't specifically say you can't charge in pitlane before qualifying. So you go out at ~8MJ, top up to 10MJ, then you can down to 6MJ after first quali lap. Recover ~1 MJ on inlap, another 2MJ on outlap for second lap, still you're nowhere near allowed recovery, and in fact are dropping total charge with each hotlap...?

It has been implied that one can run the ICE against the MGU-K as you please. This can be done for strategic deployment reasons (harvesting in a section of track without overtaking opportunity in order to defend on straights). This of course would lead to a slower ultimate laptime, but more importantly, the preservation of track position.

Take the ideal scenario. Run up against the MGU-K for most of the lap in Monaco, so you can have full deployment down both of the straights. While Monaco is already impossible to overtake on, it would just take that even further.

One could also imagine running up against the MGU-K during a safetycar or in the pitlane, to have full battery on the outlap or restart lap.

[Juzh]

pasting this from 2026 aero thread as it seems more relevant in this topic

Still can only store 4MJ.

It's probably been debated already, but you know.. 110 pages is a bit much to go trough. here's my question.
Maybe I'm missing something but is there even a plausible scenario in which a theoretical maximum of 13 MJ can be used up in a lap? Seems completely impossible, and with the removal of the mgu-h component much of the complexity is removed from the equation.

Say you start with 4 MJ stored to start the lap, recovery from braking is additional ~2 MJ at most in best of cases, so unless extra recovery is coming from the already mentioned (and supposedly not allowed as per RBPT engineer) ICE to mgu-k at 100kw what's the purpose of having extra 9 MJ available. Seems like an unreasonable amount.

In fact even starting the lap at 4 MJ stored would be a challenge without this, as regs prohibit charging the battery in garage or pitstop in excess of 100 kj.
5.4.12 The amount of stored energy in any ES may not be increased by more than 100kJ whilst the car is stationary in the pit lane or garage during the Qualifying Session or during a Race pit stop.

Ok, it doesn't specifically say you can't charge in pitlane before qualifying. So you go out at ~8MJ, top up to 10MJ, then you can down to 6MJ after first quali lap. Recover ~1 MJ on inlap, another 2MJ on outlap for second lap, still you're nowhere near allowed recovery, and in fact are dropping total charge with each hotlap...?

It has been implied that one can run the ICE against the MGU-K as you please. This can be done for strategic deployment reasons (harvesting in a section of track without overtaking opportunity in order to defend on straights). This of course would lead to a slower ultimate laptime, but more importantly, the preservation of track position.

Take the ideal scenario. Run up against the MGU-K for most of the lap in Monaco, so you can have full deployment down both of the straights. While Monaco is already impossible to overtake on, it would just take that even further.

One could also imagine running up against the MGU-K during a safetycar or in the pitlane, to have full battery on the outlap or restart lap.

Yes, this all makes sense.

However given how little energy recovery will be available via braking it's not unfeasible running ICE against mgu-k even on quali laps would be beneficial on certain (most?) tracks at the end of straights.

Problem is, if I understood correctly, we apparently have an RBPT engineer saying this is prohibited, which would be strange given the rule set.

[AR3-GP]

pasting this from 2026 aero thread as it seems more relevant in this topic


It's probably been debated already, but you know.. 110 pages is a bit much to go trough. here's my question.
Maybe I'm missing something but is there even a plausible scenario in which a theoretical maximum of 13 MJ can be used up in a lap? Seems completely impossible, and with the removal of the mgu-h component much of the complexity is removed from the equation.

Say you start with 4 MJ stored to start the lap, recovery from braking is additional ~2 MJ at most in best of cases, so unless extra recovery is coming from the already mentioned (and supposedly not allowed as per RBPT engineer) ICE to mgu-k at 100kw what's the purpose of having extra 9 MJ available. Seems like an unreasonable amount.

In fact even starting the lap at 4 MJ stored would be a challenge without this, as regs prohibit charging the battery in garage or pitstop in excess of 100 kj.
5.4.12 The amount of stored energy in any ES may not be increased by more than 100kJ whilst the car is stationary in the pit lane or garage during the Qualifying Session or during a Race pit stop.

Ok, it doesn't specifically say you can't charge in pitlane before qualifying. So you go out at ~8MJ, top up to 10MJ, then you can down to 6MJ after first quali lap. Recover ~1 MJ on inlap, another 2MJ on outlap for second lap, still you're nowhere near allowed recovery, and in fact are dropping total charge with each hotlap...?

It has been implied that one can run the ICE against the MGU-K as you please. This can be done for strategic deployment reasons (harvesting in a section of track without overtaking opportunity in order to defend on straights). This of course would lead to a slower ultimate laptime, but more importantly, the preservation of track position.

Take the ideal scenario. Run up against the MGU-K for most of the lap in Monaco, so you can have full deployment down both of the straights. While Monaco is already impossible to overtake on, it would just take that even further.

One could also imagine running up against the MGU-K during a safetycar or in the pitlane, to have full battery on the outlap or restart lap.

Yes, this all makes sense.

However given how little energy recovery will be available via braking it's not unfeasible running ICE against mgu-k even on quali laps would be beneficial on certain (most?) tracks at the end of straights.

Problem is, if I understood correctly, we apparently have an RBPT engineer saying this is prohibited, which would be strange given the rule set.

Well without this automated MGU-K harvesting, F1 may become an awful lift and coast affair.

F1 really needs to make sure this is still sprint racing, and not a hypermile competition....

[saviour stivala]

Yes. Combustion efficiency will always be the prime target of the ICE part of the power unit. The more so if less fuel use will be allowed.

not so
combustion efficiency is simply the % of the fuel charge that is burned eg c.95% for any engine type

the % of the fuel heat that is converted to work is called thermal efficiency
either indicated TE (in-cylinder measure) or brake TE (crankshaft measure)
in current F1 the ITE is c. 60% and the BTE is c. 50%

Repeat "Combustion efficiency will always be the prime target of the ICE part of the power unit''. Any differences in ICE power output between competing F1 ICE'S means differences in combustion efficiency levels. The latest developments concentrate in obtaining the fastest combustion time possible with the ability to keep the ICE reliable. The faster the combustion the reduced time available for heat-loss, sends more power to the pistons and less into cooling and exhaust. This is greater combustion efficiency.

[Tommy Cookers]

Repeat "Combustion efficiency will always be the prime target of the ICE part of the power unit''. ....
The faster the combustion the reduced time available for heat-loss, sends more power to the pistons and less into cooling and exhaust. This is greater combustion efficiency.

no it isn't greater combustion efficiency
combustion efficiency and conversion of heat to work (thermal efficiency) are accounted separately (on planet Earth)

Professor V Ganesan (multiple prize winner and author) writes - P505 'Internal Combustion Engines' (McGraw-Hill)
" Combustion efficiency is the ratio of heat liberated to the theoretical heat in the fuel. The amount of heat liberated is less than the theoretical value because of incomplete combustion either due to dissociation or due to lack of available oxygen. Combustion efficiency in a well adjusted engine varies from 92% to 97% " ....
and ....
"an indicated thermal efficiency of almost 28% is obtainable with gasoline engines having moderate compression ratio"

[saviour stivala]

''An indicated thermal efficiency of almost 28% is obtainable with gasoline engines having a moderate compression ratio''. Is this quote from Henry Ford time?.

[godlameroso]

Year 2026 new Formula one ICE part of the power unit and still dreaming of a two-valve-head, totally confusing to say the least, but claiming that a two valve head can ever match a four valve head flow is balderdash.

Where did I say that? I just said 2 valve guys have a harder time getting the same flow numbers as 4 valve heads(implying 2 valve heads have inherently less flow). You will always get more flow with 4 valves, there's just more area. 2 Valve guys know how the air is supposed to flow in the engine, which also applies to 4 valves. Say what you will, even with CNC machined billet heads, hand finishing is still beneficial.

In any case, sometimes the flow bench lies to you. It won't lie to you as bad with a direct injection engine, but it can still mislead you. More flow numbers don't necessarily translate into more power, although it generally does. It all depends on your testing methods. The plennum and exhaust runners all affect flow and reversion, or lack thereof. Seen it a lot, you have features on the CC that prevent reversion, flow great numbers, and you still end up with detonation or backfires because of poor manifold designs.

[Tommy Cookers]

''An indicated thermal efficiency of almost 28% is obtainable with gasoline engines having a moderate compression ratio''. Is this quote from Henry Ford time?.

about 100 posters here have trotted out M-B's proclamation that NA F1 (ie till 2013) was 28 or 29% efficient
so about 33% ITE

[saviour stivala]

Year 2026 new Formula one ICE part of the power unit and still dreaming of a two-valve-head, totally confusing to say the least, but claiming that a two valve head can ever match a four valve head flow is balderdash.

Where did I say that? I just said 2 valve guys have a harder time getting the same flow numbers as 4 valve heads(implying 2 valve heads have inherently less flow). You will always get more flow with 4 valves, there's just more area. 2 Valve guys know how the air is supposed to flow in the engine, which also applies to 4 valves. Say what you will, even with CNC machined billet heads, hand finishing is still beneficial.

In any case, sometimes the flow bench lies to you. It won't lie to you as bad with a direct injection engine, but it can still mislead you. More flow numbers don't necessarily translate into more power, although it generally does. It all depends on your testing methods. The plennum and exhaust runners all affect flow and reversion, or lack thereof. Seen it a lot, you have features on the CC that prevent reversion, flow great numbers, and you still end up with detonation or backfires because of poor manifold designs.

''Where did I say that?'' You said = ''2 valve guys have a harder time getting 'THE SAME FLOW NUMBERS' as 4 valve head''. You were CLEARLY implying that 2 valve heads guys can get the same flow numbers as a 4 VALVE HEADS although having a harder time.

[saviour stivala]

''An indicated thermal efficiency of almost 28% is obtainable with gasoline engines having a moderate compression ratio''. Is this quote from Henry Ford time?.

about 100 posters here have trotted out M-B's proclamation that NA F1 (ie till 2013) was 28 or 29% efficient
so about 33% ITE

NA FI TILL 2013? Silly me, and I thought we were talking about the forthcoming 2026 new generation formula one power unit, or at least the ICE combustion efficiency part of it.