2025/2026 Hybrid Powerunit speculation

[Big Tea]

Well, even with diminutive ICEs, less on-board fuel and tiny heat rejection I don't think I can see the weight reducing if overall PU output is to be conserved.

The battery will be heavier and the electric front axle will require big reduction stages for the high speed electric motors.

PU output can be traded for what has to be dragged around (and through the air). I would prefer to see a reduction of 100 hp and 100 kg.

The cars look much faster when they are nimble, and drivers tend to be more racy with them

[63l8qrrfy6]

With increased electrification it is going to go the other way regardless of what the fans want to see.

[RedNEO]

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.

Only those who stand to lose from having it taken away (Mercedes). New manufacturers are ready to take on the 2025 simpler engines and that’s what F1 is going towards.

[63l8qrrfy6]

Mercedes don't make the rules regardless of what some think

[RedNEO]

Mercedes don't make the rules regardless of what some think

That’s why I’m warning you it’s not leaning towards anything.

[godlameroso]

So ~350hp hybrid units? They're banking on 2025 having solid state batteries available or something I don't know about? A 1 liter 3 cylinder would sound pretty cool, and they could probably squeeze ~550hp out of it?

[63l8qrrfy6]

Half the fuel flow rate at 60% TE is about 490hp which means they need to find another 510hp from electric motors.

[63l8qrrfy6]

**Moved from the 2021 PU thread**

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.

[nzjrs]

**Moved from the 2021 PU thread**

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.

Very interesting. Any explicit or implicit acknowledgement of bio-fuels for the ICE part?

[63l8qrrfy6]

Yes, FIA have revealed the spec sustainable fuel composition at the conference (I think it's public now, haven't had the chance to look it up) and are in process of providing samples to current manufacturers and any interested parties.

[hollus]

When I hear half the displacement, half the fuel, half the power, I get the impression that they set the bar too low on purpose to be able to raise it as a concession during negotiations.
Half sounds too small.
And a 0.x L engine sounds... toy-ish. My VW Up had a larger engine! MotoGP had a larger engine!

I expect it to be 1.2, based on nothing but gut feeling.

[63l8qrrfy6]

I think it confirmed my initial suspicion that in the drive to keep costs low FIA intend to keep it simple and get rid of one bank of cylinders.

Along the same lines, the "cheapest" way to increase displacement is to increase the stroke, this way the bore, bore spacing, heads and valvetrain can remain unchanged. In doing so the mean piston speed* increases for a given engine speed so for example if they made the engines 1000cc with 80mm bore, 66mm stroke the maximum speed may be decreased to 12000 RPM to keep the mps to about 26.4 m/s which is slighlty above what they currently do at 15000 RPM.

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.

A 1200cc l3 engine with 80mm bore will require a 80mm stroke and could only rev up to 10000 RPM before reaching a mps of 26.6 m/s.

If I had to put money on it I'd say that most likely is an inline 3 engine between 800cc and 1200cc capacity and the second most likely would be a 1000cc to 1200cc V4.

*inertial piston stresses are caused by acceleration rather than speed but it's so much simpler to work out mps on the phone calculator without having to whip out excel.

[LM10]

V6's all sound like vacuum cleaners. It's the wrong number of bores. Nothing sounds better than a V12, but that's too many for this day and age. The V4 in the 919 was a nice little engine. Had a decent sound to it, much better than a vacuum cleaner V6.

[Big Tea]

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

[gruntguru]

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.

I think allowing an extra injector per cylinder would have been a logical and obvious addition to that list. The current engines use a technology that was developed to work with two injectors per cylinder and is likely compromised by the one-injector rule.