2025/2026 Hybrid Powerunit speculation

[gruntguru]

The longer stroke is very useful for increasing compression ratio and the lower engine speed would also help drive thermal efficiency up. On the other hand, for a fixed fuel flow rate, an engine with greater capacity will have a lower thermal efficiency due to higher thermal losses in the larger surface area of the combustion chamber.

Less of a problem when the extra capacity is gained using a longer stroke. The added piece of cylinder (at the bottom) only sees cooler parts of the cycle.

[gruntguru]

As much as I would like to see it, I think there would be a big mental step in reducing capacity below 1ltr.
Is seems sort of 'unmanly' to fall below 1.000 cc, even in bikes these days

Need to make that step somewhere along the path to "no combustion engine at all".

[graham.reeds]

Would removing the engine as a driver of wheels and make it just for recharging the batteries work?

[mzso]

Obviously they will increase battery capacity and electric motor power to compensate.

What's obvious is that that's impossible.

[mzso]

Obviously they will increase battery capacity and electric motor power to compensate.

And hopefully reduce weight by at least 30%

With more batteries???

[Holm86]

We have shell eco marathon for those who like teeny weeny ultra efficient engines, and formula e for those who like electric racing.

Don't hope the engine group gets too cought up in making tiny ICE's with the majority of power coming from electrics.
They should rather focus on renewable carbon neutral fuels, and then let them use those fuels in regular ICE's.

And I would prefer if the engines became simpler, to attract more manufacturers.

1.6 V4 hybrid,with an increase in ES and MGU-K power, and run it on bio fuels. Problem with bioethanol etc. is it's got half the energy content of regular fuel, and would need much bigger fuel tanks.

And gearboxes should be 6 gears, instead of 8.

[Just_a_fan]

WProblem with bioethanol etc. is it's got half the energy content of regular fuel, and would need much bigger fuel tanks.

The other problem with bioethanol is that it's not seen as being really very "green" these days. There is political movement against it as it's seen as using up food land and being responsible for deforestation. No point trumpeting your green credentials if you're associated with the chopping down of virgin forest/jungle to make the fuel. Even if your fuel is made in a big container in a factory unit using kitchen scraps. Some serious marketing required to ensure that the correct message goes out.

The "petrol from the air" fuels would make more sense if you're wanting to be seen as being non-fossil fuel / Carbon neutral etc. And they would have similar energy density to dino-juice too which removes the fuel tank size issue.

[63l8qrrfy6]

The longer stroke is very useful for increasing compression ratio and the lower engine speed would also help drive thermal efficiency up. On the other hand, for a fixed fuel flow rate, an engine with greater capacity will have a lower thermal efficiency due to higher thermal losses in the larger surface area of the combustion chamber.

Less of a problem when the extra capacity is gained using a longer stroke. The added piece of cylinder (at the bottom) only sees cooler parts of the cycle.

I agree, however the FMEP will also increase with the stroke at a given engine speed.

[Holm86]

WProblem with bioethanol etc. is it's got half the energy content of regular fuel, and would need much bigger fuel tanks.

The other problem with bioethanol is that it's not seen as being really very "green" these days. There is political movement against it as it's seen as using up food land and being responsible for deforestation. No point trumpeting your green credentials if you're associated with the chopping down of virgin forest/jungle to make the fuel. Even if your fuel is made in a big container in a factory unit using kitchen scraps. Some serious marketing required to ensure that the correct message goes out.

The "petrol from the air" fuels would make more sense if you're wanting to be seen as being non-fossil fuel / Carbon neutral etc. And they would have similar energy density to dino-juice too which removes the fuel tank size issue.

The ethanol was just an example, if they can get carbon from air to make fuels, thats great, I just want to keep the combustion engines, without it having to be a fuel saving excercise

[Tommy Cookers]

increased heat dilution is needed so .....
2 stage supercharging and 'pre-chamber' fuel with greater explosive range (ie gas or low vapour pressure liquid)

ICE as prime mover only ?
(low-speed) free-piston engine or similar 'crankless' engine driving linear generator
constant power or not ?

no gears or lots of gears ?
the 8 gear transmission helps the electrical side a lot

[Big Tea]

Obviously they will increase battery capacity and electric motor power to compensate.

And hopefully reduce weight by at least 30%

With more batteries???

Leave it open. If they feel they can develop batteries down to that weight, fine.
Otherwise develop capacitors, flywheels mice in cages, whatever.
If there is a requirement, they will meet it.

[Just_a_fan]

It would be an interesting process to watch if the FIA just said "you have 100 litres of fuel(*) to do the race, go and build your PU to make the best use of it. Car has to meet the usual other requirements for safety and aero limits. What have you got?"

(*)If the fuel allowance is below a certain critical value, some form of hybrid systems will be required to be competitive. The question is what is the critical fuel amount that forces the engineers to do more than just ask the drivers to lift and coast? Storing some of the wasted energy will be required in order to be competitive.

[NL_Fer]

I've got in touch with someone who attended the ImechE conference I've mentioned in the previous posts. Did not manage to get any of the presentations but I was provided with a very good summary:

FIA has contracted IFPEN Transports Energie Carnot Institute (https://www.ifpenergiesnouvelles.com/in ... -institute) to study different options for future F1 PUs. FIA's initial guidelines suggests ultra-downsizing to roughly half the current engine displacement. Fuel mass flow and on-board fuel will halve. BTE target is set to 60%. Emission regulations and P4 hybridization with front axle recovery have also been suggested but do not appear to be firm targets.

Technologies proposed to achieve these objectives include:
-Removing the CR limit
-HCCI and spark-assisted HCCI
-2 stage supercharging
-Water injection

At the moment they seem to be leaning towards keeping the MGUH.
Teams are expected to feed back which of these technologies they would like to pursue. As manufacturers start finding common ground the regulations will start to firm up.

This would suggest that in future they continue the same race for more efficiency and performance as we have seen the past 6 years. Any idea’s how prevent another expensive development war? I doubt that current manufacturers or any potential new entrant would be interested in burning another bilion each.

I do believe that MGU-H or another form of Exhaust Heat Recovery is still on the table. Porsche preferred it over front brake recovery, for the 919 WEC racer. Exhaust Heat Recovery is very efficient, smaller, lighter and also not influence the feeling of the front brakes.

To bad it’s also a big muffler...

[Big Tea]

It would be an interesting process to watch if the FIA just said "you have 100 litres of fuel(*) to do the race, go and build your PU to make the best use of it. Car has to meet the usual other requirements for safety and aero limits. What have you got?"

(*)If the fuel allowance is below a certain critical value, some form of hybrid systems will be required to be competitive. The question is what is the critical fuel amount that forces the engineers to do more than just ask the drivers to lift and coast? Storing some of the wasted energy will be required in order to be competitive.

Would it not be better to just state the maximum flow rate if you want to open up options?
This would mean for power to be used alongside the ICE when at maximum requirement, and stored when there is spare capacity?

[Just_a_fan]

It would be an interesting process to watch if the FIA just said "you have 100 litres of fuel(*) to do the race, go and build your PU to make the best use of it. Car has to meet the usual other requirements for safety and aero limits. What have you got?"

(*)If the fuel allowance is below a certain critical value, some form of hybrid systems will be required to be competitive. The question is what is the critical fuel amount that forces the engineers to do more than just ask the drivers to lift and coast? Storing some of the wasted energy will be required in order to be competitive.

Would it not be better to just state the maximum flow rate if you want to open up options?
This would mean for power to be used alongside the ICE when at maximum requirement, and stored when there is spare capacity?

I don't know. Is a fuel flow rate a better restriction or is just a total fuel amount as good/better?