2025/2026 Hybrid Powerunit speculation

[karana]

(given that there's 5 permitted fueling events)
extra gas could be made late in the stroke - increasing MGU-H made electricity rather than ICE power
maybe other effects
Honda had a name for the increased electricity

Based on this, are we sure 'engine power' in

C5.2.5 At partial load, the fuel energy flow must not exceed the limit curve defined below:
EF (MJ/h) = 380 when the engine power is equal to or below −50kW
EF (MJ/h) = 9.78 x engine power (kW) + 869 when the engine power is above −50kW

really refers to the PU power?

It has to.

An ICE should not achieve a negative power (known as engine braking) while burning any fuel.

If fuel is burnt, a positive power is produced by the ICE.

If MGUK recovers more than the ICE is outputting, it amounts to a negative power.

This wording of the rules is, at least, not fully conclusive, but any other interpretation would be anti lag (burning fuel with exhaust valve fully open and no power being extracted by the ICE).

Could an ICE not achieve negative power by delaying the ignition?

As I mentioned in an earlier post there are a couple of instances where the Tech Regs use the term "engine power" which can easily confuse since the PU as a whole is not strictly an "engine". The ICE is an engine and the PU as a whole is an engine - hybrid-transmission combination.

The term "engine power" appears exactly three times in the technical regulations, all in C5.2.5.
I actually searched for all appearences of "engine". To me it looks like it always refers solely to the ICE.

Also: Appendix C1:Definitions

“Engine” (“ICE”): The internal combustion engine including Ancillaries and actuator systems
necessary for its proper function

[saviour stivala]

''If MGU-K recovers more than the ICE is outputting, it amounts to negative power''. No, it's not a question of 'negative power', but a matter of energy balance. Confusion arises from the fact that the ICE is still running during a braking event, but its output is much lower than the kinetic energy being recovered by the MGU-K.

[gruntguru]

Could an ICE not achieve negative power by delaying the ignition?

It could (even without burning fuel) by using pumping losses but that would be a bad idea - it would waste an opportunity to harvest energy via the MGU-K.

[gruntguru]

As I mentioned in an earlier post there are a couple of instances where the Tech Regs use the term "engine power" which can easily confuse since the PU as a whole is not strictly an "engine". The ICE is an engine and the PU as a whole is an engine - hybrid-transmission combination.

The term "engine power" appears exactly three times in the technical regulations, all in C5.2.5.
I actually searched for all appearences of "engine". To me it looks like it always refers solely to the ICE.
Also: Appendix C1:Definitions

“Engine” (“ICE”): The internal combustion engine including Ancillaries and actuator systems
necessary for its proper function

As I said, the term "engine power", as used in 5.4.5 is an error in the Tech Regs.

1. There is no possibility that the Tech Regs would allow for negative ICE power
2. The formula referring to "engine power" (EF (MJ/h) = 9.78 x engine power (kW) + 869 when the engine power is above -50kW) does not make sense if you plug valid values of ICE power into it.

[wuzak]

As I mentioned in an earlier post there are a couple of instances where the Tech Regs use the term "engine power" which can easily confuse since the PU as a whole is not strictly an "engine". The ICE is an engine and the PU as a whole is an engine - hybrid-transmission combination.

The term "engine power" appears exactly three times in the technical regulations, all in C5.2.5.
I actually searched for all appearences of "engine". To me it looks like it always refers solely to the ICE.
Also: Appendix C1:Definitions

“Engine” (“ICE”): The internal combustion engine including Ancillaries and actuator systems
necessary for its proper function

As I said, the term "engine power" is an error in the Tech Regs.

1. There is no possibility that the Tech Regs would allow for negative ICE power
2. The formula referring to "engine power" (EF (MJ/h) = 9.78 x engine power (kW) + 869 when the engine power is above -50kW) does not make sense if you plug valid values of ICE power into it.

It is also does not make sense to limit ICE output with fuel flow based on the actual ICE output.

[diffuser]

for 2026 there seems to be no consumption limit ?? - only a fuel (heat) rate limit
again to help the least competitive teams give a better impression eg by having sufficient electrical energy

There is an energy limit, isn't there? Which based on the fuel blend will be calculated in to fuel mass.

Not that I have seen so far.

The regs say ..
Fuel properties
The only fuel permitted is petrol having the following characteristics:

Property Units             Min      Max    Test Method
RON                    95.0(1) 102.0(1)    ISO 5164/ ASTM D2699
Sensitivity (RON-MON)           15.0(1)    ISO 5164/ ASTM D2699 
                                           ISO 5163/ ASTM D2700

Wouldn't a max flow of 3000mj/h be about 90Liters of 100 octane gasoline in 1 hour?

[wuzak]

Fuel density is between 720kg/m³ and 785kg/m³.

Energy density is between 38.0MJ/kg and 41.0MJ/kg.

For 3000MJ, the fuel weight is between 78.9kg and 73.2kg.

The volume of fuel will be between 93L (highest energy density and highest SG) and 109L (lowest energy density and lowest SG) depending on those properties.

[diffuser]

Fuel density is between 720kg/m³ and 785kg/m³.

Energy density is between 38.0MJ/kg and 41.0MJ/kg.

For 3000MJ, the fuel weight is between 78.9kg and 73.2kg.

The volume of fuel will be between 93L (highest energy density and highest SG) and 109L (lowest energy density and lowest SG) depending on those properties.

Means they're gonna have to have tanks that can hold 150 liters? Maybe more? I mean lots of tracks are 65% full throttle and now you'll be burning fuel off full power demand to charge the battery.

[BassVirolla]

Fuel density is between 720kg/m³ and 785kg/m³.

Energy density is between 38.0MJ/kg and 41.0MJ/kg.

For 3000MJ, the fuel weight is between 78.9kg and 73.2kg.

The volume of fuel will be between 93L (highest energy density and highest SG) and 109L (lowest energy density and lowest SG) depending on those properties.

Means they're gonna have to have tanks that can hold 150 liters? Maybe more? I mean lots of tracks are 65% full throttle and now you'll be burning fuel off full power demand to charge the battery.

... and call it heavily electrified.

[Tommy Cookers]

... and call it heavily electrified.

but isn't this the 50/50 that we've all been waiting for ? ....

[diffuser]

... and call it heavily electrified.

but isn't this the 50/50 that we've all been waiting for ? ....

It's so dumb that they got rid of the MGU-H. They should have just made it a standard part. Maybe soemthing that's like Honda's that all 1 piece with the turbo, to keep the price down. That's the MGU-H is a big fuel saver.

[wuzak]

Fuel density is between 720kg/m³ and 785kg/m³.

Energy density is between 38.0MJ/kg and 41.0MJ/kg.

For 3000MJ, the fuel weight is between 78.9kg and 73.2kg.

The volume of fuel will be between 93L (highest energy density and highest SG) and 109L (lowest energy density and lowest SG) depending on those properties.

Means they're gonna have to have tanks that can hold 150 liters? Maybe more? I mean lots of tracks are 65% full throttle and now you'll be burning fuel off full power demand to charge the battery.

Probably about what they have now.

[diffuser]

Fuel density is between 720kg/m³ and 785kg/m³.

Energy density is between 38.0MJ/kg and 41.0MJ/kg.

For 3000MJ, the fuel weight is between 78.9kg and 73.2kg.

The volume of fuel will be between 93L (highest energy density and highest SG) and 109L (lowest energy density and lowest SG) depending on those properties.

Means they're gonna have to have tanks that can hold 150 liters? Maybe more? I mean lots of tracks are 65% full throttle and now you'll be burning fuel off full power demand to charge the battery.

Probably about what they have now.

Pretty sure they're ~ 110L now.

[Tommy Cookers]

the current or recent rules allow(ed) 110 kg of fuel consumption (plus a sampling quantity)
suggesting a tank volume up to roughly 150 litres

[vorticism]

So, same amount of fuel to go slower? Any chance that the 70kg/hr fuel flow rate could lead to similar or better thermal efficiency from the ICE? Simply by reducing boost & fuel within the same capacity engine. And will the PU unit as a whole be able to match or surpass the ~50% TE of the current PUs? That would be the ultimate measure. Can these cars run a race with less fuel or not. Otherwise it's a step back in terms of efficiency. It might be hard to tell with the active aero they're adding. If the '26 PUs prove to be less efficient then it seems like their primary design criteria will have to be considered as cost reduction. Like '05 to '06, where the engines became less powerful in the name of cost saving. Some of the magic was lost and that might be the case again.