2025/2026 Hybrid Powerunit speculation

[bananapeel23]

What I'm wondering, after watching the 'race starts' with the 10 second full throttle engine turbo spin-up stuff, is what will pit stops look like. Can the cars use electric power to leave the pits? Does the 50 kph rule apply? If it does then it will be very interesting. And if it doesn't it will be interesting.

They will be sitting in first and revving as high as possible to harvest as much as possible from the MGU-K when in the pitlane. That means they can deploy like crazy on the in lap and deploy like crazy on the out lap, since they will enter the pit lane with an empty battery and exit it with a fully charged one.

[FW17]

Can the engine and gearbox be made to launch at full throttle, 12-15k rpm?




WRC cars launch has similar spooling for boost as current F1, but they seem to launch at full throttle, unlike the current f1 practice starts where they go part throttle before lights off

[eyelid]

What I'm wondering, after watching the 'race starts' with the 10 second full throttle engine turbo spin-up stuff, is what will pit stops look like. Can the cars use electric power to leave the pits? Does the 50 kph rule apply? If it does then it will be very interesting. And if it doesn't it will be interesting.

They will be sitting in first and revving as high as possible to harvest as much as possible from the MGU-K when in the pitlane. That means they can deploy like crazy on the in lap and deploy like crazy on the out lap, since they will enter the pit lane with an empty battery and exit it with a fully charged one.

Really, harvesting that big battery only from pitlane distance? Sure they're doing that as it's effective way, but I can hardly believe that at the pitlane exit it will be 100% charged.

[bananapeel23]

What I'm wondering, after watching the 'race starts' with the 10 second full throttle engine turbo spin-up stuff, is what will pit stops look like. Can the cars use electric power to leave the pits? Does the 50 kph rule apply? If it does then it will be very interesting. And if it doesn't it will be interesting.

They will be sitting in first and revving as high as possible to harvest as much as possible from the MGU-K when in the pitlane. That means they can deploy like crazy on the in lap and deploy like crazy on the out lap, since they will enter the pit lane with an empty battery and exit it with a fully charged one.

Really, harvesting that big battery only from pitlane distance? Sure they're doing that as it's effective way, but I can hardly believe that at the pitlane exit it will be 100% charged.

They get something like 1.5 to 2 seconds of braking while getting down to the pit lane speed limit, where they would be harvesting at 350 kW (assuming they can indeed reach the 350 kW limit), which works out to another 0.15-0.2 kWh, or about 1/6 of a full battery charge.

So they have to get roughly the remaining 85% of the battery charge while under the pit lane speed limit, or roughly 0.95 kWh.

An average pit lane takes roughly 20 seconds to drive though at 80 km/h. So the recharge rate (r) required would be (20/3600) * r = 0.935. If you do the math, r works out to about 168. So the MGU-K would need to sustain only 168 kW of recharging through the pitlane in order to fully recharge the battery. That is well below the 250 kW limit for on-throttle regen.

Obviously this is under ideal conditions where they get the full 350 kW for the entire braking duration, but in reality the recharging rate through the pit lane shouldn't have to exceed perhaps 180 kW. So from a purely mathematical standpoint, the cars could easily charge the battery fully in the pit lane. If it's possible in practice, I'm not sure.

My primary concern would be overheating. I don't know whether or not the heat load from recharging like this in the pit lane with limited cooling at 80 km/h would cause over heating. The second question is whether or not this rate of charging is even possible at 80 km/h with the current engines, which I can't answer either.

[venkyhere]

My primary concern would be overheating. I don't know whether or not the heat load from recharging like this in the pit lane with limited cooling at 80 km/h would cause over heating. The second question is whether or not this rate of charging is even possible at 80 km/h with the current engines, which I can't answer either.

rate of charging is going to depend on the RPM, not the vehicle speed. Whatever be the gear chosen by the driver is going to be, the algorithm can be made to provide 80kph wheel speed in that gear, and adjust the 'charging load' (by playing with the stator's magnetic field) such that : (ICE generated hp) = 250/350KW charging load + (hp needed to move at 80kph). Yes, whether the ICE can run at such load for 20-25 seconds with limited airflow - of course that will decide the 'charging load' as well.

[bananapeel23]

My primary concern would be overheating. I don't know whether or not the heat load from recharging like this in the pit lane with limited cooling at 80 km/h would cause over heating. The second question is whether or not this rate of charging is even possible at 80 km/h with the current engines, which I can't answer either.

rate of charging is going to depend on the RPM, not the vehicle speed. Whatever be the gear chosen by the driver is going to be, the algorithm can be made to provide 80kph wheel speed in that gear, and adjust the 'charging load' (by playing with the stator's magnetic field) such that : (ICE generated hp) = 250/350KW charging load + (hp needed to move at 80kph)

Yeah. It's a tough balancing act. My concern about recharging at 80 km/h was more about whether that sweet spot can be found, which I can't answer, even if I suspect that it can.

[Tommy Cookers]

isn't the MG torque capped at 500 Nm (crankshaft equivalent) for all (crankshaft) rpm below c.6200 ?

[venkyhere]

isn't the MG torque capped at 500 Nm (crankshaft equivalent) for all (crankshaft) rpm below c.6200 ?

even if such a limit is present, aren't the initial few gears short enough to make the engine revv beyond 6200 for vehicle speed of 80kph ?

Which triggers another doubt (pardon if it has been already answered, unable to keep up with the pace of posts coming in this thread) :
My understanding is that the MGU-K is a 'wrap-around' on the main driveshaft, upstream of gearbox+diff ; hence the ICE can be used to recharge the battery even in neutral. Is this 'allowed' by the rules OR is there an engg-limitation that prevents this from happening ? In case recharging can happen in neutral, what about the rear-jackman who will be blasted with tremendous hot exhaust during the pitstop ?

[michl420]

The MGUK need 12 s under full power to fill (or empty) the battery. That should be possible in the pit lane. But I don´t know if the regulation allow it. And heat could also be a concern.

[michl420]

isn't the MG torque capped at 500 Nm (crankshaft equivalent) for all (crankshaft) rpm below c.6200 ?

even if such a limit is present, aren't the initial few gears short enough to make the engine revv beyond 6200 for vehicle speed of 80kph ?

Which triggers another doubt (pardon if it has been already answered, unable to keep up with the pace of posts coming in this thread) :
My understanding is that the MGU-K is a 'wrap-around' on the main driveshaft, upstream of gearbox+diff ; hence the ICE can be used to recharge the battery even in neutral. Is this 'allowed' by the rules OR is there an engg-limitation that prevents this from happening ? In case recharging can happen in neutral, what about the rear-jackman who will be blasted with tremendous hot exhaust during the pitstop ?

The MGUK is in front of the ICE fix coupled with the crankshaft. RPM should also be no problem, because last year they drive normaly with the 2. gear in the pit lane. This year they can just use the first gear. This could also a (small) reason for first gear ratio choice.

[vorticism]

- what conditions are the 1.6L capacity measured?
- Must this 1.6L limit be maintained at all times during normal operating conditions?
- How is this policed?

...

How can the 1.6L be so well controlled...

The FIA define cubic capacity as the swept volume of the pistons i.e. the volume encapsulated by the bore and the two most distant positions of the piston face. We don't, afaik, know how the FIA measures this, or when they inspect it. It is potentially easy to measure, as all you need to do is measure any fixed point upon the piston crown through its full travel. The size of the combustion chamber volume is not regulated directly but the spec GCR limits its minimum volume to around 18cc. Which means the total closed capacities of the engines are around 1.7l minimum.

To say it in a more confusing way: the "cubic capacity" is dictated by the spec bore diameter & cylinder count, while the cubic capacity is defined by the geometric compression ratio.

I would consider swept volume as displacement in the true sense of that term, not necessarily as capacity--regular terms in the ICE world often have multiple connotations and can be considered colloquialisms. There may even be translation artifacts between languages.

The question of how the ~1.7 liter and 108cc closed capacities i.e. the large and small parts of the GC ratio are potentially measured is the more prescient question in regards to the recent rumors.

If teams were allowed to use any values for bore, stroke, and displacement that they wanted (given the current allowed energy/hour), what might they choose?

I’m intrigued by this oddly specific question. What made you choos these three variables and only these three variables to be freed up among the dozens?

If the rest of the regulations were maintained in their entirety (cyl count, boost limit, fuel energy curve, prescribed 10.5k RPM powerband low end, compression ratio, etc) and only those three dimensions were deregulated, I can offer some guesses:

--little change, the oversquare stroke ratio and the displacement are ideal within that regulatory domain
--they might choose to reduce displacement as much as they can while going as oversquare as they can (to maximize valve area), as this would be a way to increase BMEP in spite of the CR & boost limits (they can’t chase BMEP in the other direction, with higher displacement, bigger bang, low RPM diesel-like concepts, due to you maintaining the fuel curve)
--little benefit to going square or undersquare, as the CR is prescribed and since boost (airflow) is limited you’d need as a development target of more valve area not less

[Farnborough]

Are those three question about how to ensure compliance with existing rules OR how to formulate a design and specification that's effective as racing engine ?

[chipengineer]

[/quote]

I’m intrigued by this oddly specific question. What made you choos these three variables and only these three variables to be freed up among the dozens?

If the rest of the regulations were maintained in their entirety (cyl count, boost limit, fuel energy curve, prescribed 10.5k RPM powerband low end, compression ratio, etc) and only those three dimensions were deregulated, I can offer some guesses:

--little change, the oversquare stroke ratio and the displacement are ideal within that regulatory domain
--they might choose to reduce displacement as much as they can while going as oversquare as they can (to maximize valve area), as this would be a way to increase BMEP in spite of the CR & boost limits (they can’t chase BMEP in the other direction, with higher displacement, bigger bang, low RPM diesel-like concepts, due to you maintaining the fuel curve)
--little benefit to going square or undersquare, as the CR is prescribed and since boost (airflow) is limited you’d need as a development target of more valve area not less
[/quote]

The purpose was to understand whether engine thermal efficiency (and therefore power output) could be improved if some seemingly artificial restrictions were removed. I listed the ones whose only purpose appears to be avoiding change from the previous formula. Feel free to eliminate other restrictions if they have no reasonable purpose. Number of cylinders might be another, unless manufacturer marketing is the purpose.
I was also assuming keeping the other 2026 rules.

[chipengineer]

'nuclear power' produces substantial global warming - increasing Earth's heat then dumping most of that increase
these are in law nuclear space heaters (not heat engines) because they are only 35% efficient as engines
their actual GW is 15-20% as bad (relatively) as the GW from 'greenhouse gas' engine power

yes wind farms don't increase Earth's heat - they redistribute natural heat flow so produce substantial warming regionally
(so it's ok because it's not GW ?)
because wind is made by equatorial heat and wind power dumps as heat more energy than it captures
the paper from ScienceDirect predicts 0.24 deg C warming on USA conversion to windfarm electricity
so maybe 1 deg C warming (rather offsetting the ghg savings) from the lavish changes ongoing in the UK

and of course any man-made heat (eg the 10% electricity losses in transmission) is GW in reality (if not in law)

The waste heat (measured in power) generated by all the world's electric power plants is 0.0056% of the power Earth absorbs from the sun. So power plant efficiency does not really matter as far as generating global heat.

[chipengineer]

'nuclear power' produces substantial global warming - increasing Earth's heat then dumping most of that increase
these are in law nuclear space heaters (not heat engines) because they are only 35% efficient as engines
their actual GW is 15-20% as bad (relatively) as the GW from 'greenhouse gas' engine power

yes wind farms don't increase Earth's heat - they redistribute natural heat flow so produce substantial warming regionally
(so it's ok because it's not GW ?)
because wind is made by equatorial heat and wind power dumps as heat more energy than it captures
the paper from ScienceDirect predicts 0.24 deg C warming on USA conversion to windfarm electricity
so maybe 1 deg C warming (rather offsetting the ghg savings) from the lavish changes ongoing in the UK

and of course any man-made heat (eg the 10% electricity losses in transmission) is GW in reality (if not in law)

The waste heat (measured in power) generated by all the world's electric power plants is 0.0056% of the power Earth absorbs from the sun. So power plant efficiency does not really matter as far as generating global heat.