2025/2026 Hybrid Powerunit speculation

All that has to do with the power train, gearbox, clutch, fuels and lubricants, etc. Generally the mechanical side of Formula One.
Tommy Cookers
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Re: 2025/2026 Hybrid Powerunit speculation

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bananapeel23 wrote:
Thu May 16, 2024 1:01 pm
.... but still has a really strong focus on combustion efficiency .....
the significant matter isn't combustion efficiency CE - it's indicated thermal efficiency ITE

combustion efficiency is simply the percentage of fuel burnt (eg 95%) without any regard to conversion of heat to work
there's no reason to think the CE of these cars is outstanding (even though there can be a bit of post-cylinder burning)

the ITE is outstanding - and yes that's largely due to the novel and nearer-to-ideal combustion rate behaviour
ITE is the ratio of work developed in cylinder (ie work at piston crown) to the heat released in-cylinder
(it is derived from the continuous measurement of in-cylinder' pressure and volume)

what science types parrot as 'thermal efficiency' is correctly known by engineers as brake thermal efficiency BTE
BTE is the ratio of work (at the crankshaft nose) to the heat (lower heating value LHV) of the fuel taken
(LHV ignores the fuel heat heat 'trapped' as latent heat in exhaust water and fuel vapours)

gruntguru
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Re: 2025/2026 Hybrid Powerunit speculation

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Hoffman900 wrote:
Thu May 16, 2024 1:34 pm
From Pat Symond’s presentation:
. . . .
* Lambda 1.3-1.4.
. . . .
* They are Miller Cycle engines, with IVC before BDC
. . . .
* Modeling from the FIA shows around 5.5bar boost (~80psi or so)
It is years since I ran the numbers but it would be interesting to extract the VE from those above. Certainly well below 100%.

Couldn't resist - here we go. Feel free to correct any dodgy assumptions.

Fuel flow = 100 kg/hr. (100/60 kg/min)
Airflow = fuel flow x AFR = 100/60 x 14.7 x 1.35 = 33.1 kg/min
5.5 bar boost = 6.5 P.R. lets assume intercooling is not down to ambient so density ratio (DR) is only 5.0
Air density = 1.2 x DR = 6 kg/m3
Air volume flow = air mass flow/density = 33.1/6 = 5.5 m3/min = 5,500 l/min
Air volume flow also = rpm x displacement/2 x VE
So VE = volume flow x 2 / rpm / displacement = 5,500 x 2 /10,500 / 1.6 = 0.65
VE = 65% (Killed by EIVC.)
Probably pessimistic. eg DR = 5.0 sounds high to me.
je suis charlie

Tommy Cookers
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Re: 2025/2026 Hybrid Powerunit speculation

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I think re the FIA they meant 5.5 bar absolute ....
haven't they issued in the 2026 rules a pressure limit in absolute terms ?

PS in the 80s it's said 'boost' was limited to 4 bar then 2.5 bar - but it was actually 4 bar absolute then 2.5 bar absolute
Last edited by Tommy Cookers on Sun May 19, 2024 8:42 am, edited 1 time in total.

wuzak
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Re: 2025/2026 Hybrid Powerunit speculation

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Tommy Cookers wrote:
Sat May 18, 2024 12:46 pm
I think re the FIA they meant 5.5 bar absolute ....
haven't they issued in the 2026 rules a pressure limit in absolute terms ?
5.5.2 Engine intake air pressure must be less than 4.8 barA at all times. The pressure of the air will be measured by two FIA approved and sealed devices through which all air destined for combustion must flow. These devices must be installed in FIA approved locations situated in the engine inlet intake air system downstream of the charge air cooling system (as described in Article 5.25.2).

CaribouBread
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Re: 2025/2026 Hybrid Powerunit speculation

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Slightly OffTopic but there's some irony in the fact that Audi/Porsche were the main force in getting rid of the MGUH for these new regs, but now Porsche is making a 911 GTS with a MGUH/MGUK PU. Something something "road relevance" :mrgreen: =D>

Cold Fussion
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Re: 2025/2026 Hybrid Powerunit speculation

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CaribouBread wrote:
Tue May 28, 2024 4:08 pm
Slightly OffTopic but there's some irony in the fact that Audi/Porsche were the main force in getting rid of the MGUH for these new regs, but now Porsche is making a 911 GTS with a MGUH/MGUK PU. Something something "road relevance" :mrgreen: =D>
Before any of the other manufacturers add MGU-H's to their road car engines no less.

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Holm86
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Re: 2025/2026 Hybrid Powerunit speculation

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CaribouBread wrote:
Tue May 28, 2024 4:08 pm
Slightly OffTopic but there's some irony in the fact that Audi/Porsche were the main force in getting rid of the MGUH for these new regs, but now Porsche is making a 911 GTS with a MGUH/MGUK PU. Something something "road relevance" :mrgreen: =D>
When I heard they were making a 911 Hybrid I instantly thought 'how boring' but the tech in their new T-Hybrid system is actually pretty cool.

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Vanja #66
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Re: 2025/2026 Hybrid Powerunit speculation

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2026 PUs are going to reach 1100 HP according to Tombazis

https://www.racefans.net/2024/06/12/for ... s-in-2026/
And they call it a stall. A STALL!

#DwarvesAreNaturalSprinters
#BlessYouLaddie