2025/2026 Hybrid Powerunit speculation

[saviour stivala]

The presently used F1 BBW system used on rear wheels is indeed a fail-safe system. As long as teams does not contravene the rules/regulations like happened in Japan by a particular team and which was uncovered after that fatal accident.

[Big Tea]

If we're heading towards electrification. I wonder if it would make sense to allow cryo-cooling, or whether it would be prohibitively expensive and complicated to sustain, or have any real-world relevance for the foreseeable future.

I definitely would mandate direct drive. It would be an added challenge on motor design. But ultimately gears always add unreliability and inefficiency, plus there's nothing to develop there.
Ultimately I would move it forward 4WD as well, with re-gen braking only.

Well that would certainly extend the braking distances, which might be no bad thing. I would guess that peak braking effort might be halved at least.

You could be on to something to improve the racing here? Restrict the speed of recovery/time and amount of fuel so the distance has to be longer under normal race conditions and we could see some passing into or out of corners like the old times

[Jolle]

If we're heading towards electrification. I wonder if it would make sense to allow cryo-cooling, or whether it would be prohibitively expensive and complicated to sustain, or have any real-world relevance for the foreseeable future.

I definitely would mandate direct drive. It would be an added challenge on motor design. But ultimately gears always add unreliability and inefficiency, plus there's nothing to develop there.
Ultimately I would move it forward 4WD as well, with re-gen braking only.

Well that would certainly extend the braking distances, which might be no bad thing. I would guess that peak braking effort might be halved at least.

You could be on to something to improve the racing here? Restrict the speed of recovery/time and amount of fuel so the distance has to be longer under normal race conditions and we could see some passing into or out of corners like the old times

The problem with somehow restricting braking force, is that it’s not on the edge of locking up anymore, there is no skill involved. Bit like ABS. You just flip the brake switch and wait until you can turn in. Until software is so good that a BBW system has as much feel as a normal system, it’s not an option for F1

[Tommy Cookers]

.... Bit like ABS.
......Until software is so good that a BBW system has as much feel as a normal system, it’s not an option for F1

a regenerative braking system will act rather (or entirely) like ABS

NOTE TO SELF and NB !
the 'natural' quasi-steady-state characteristic in regenerative braking is pro-wheel-locking
the quasi-steady-state characteristic of a torque-controlled regen system is neutral
there's true dynamic response effects with rapid changes in load
then there's designed beneficial torque collapse with rapid changes on load - giving some emulation of ABS and TC
4 MGs might give stronger ABS/TC emulation - and even a steer-by-brake effect

the effect of the present low K torque limit is to disguise the ABS element
(also with the mixed braking system making friction braking sacred there is some 'lumpiness' - helping the disguise)

[Zynerji]

.... Bit like ABS.
......Until software is so good that a BBW system has as much feel as a normal system, it’s not an option for F1

any regenerative braking system will act rather (or entirely) like ABS

the effect of the present low K torque limit is to disguise the ABS element
(also with the mixed braking system making friction braking sacred there is some 'lumpiness' - helping the disguise)

electric awd by 4 MGs - how isn't that ABS and TC emulation and scope for other things that we see as driver aids ?

If front wheel motors were independently operated by triggers on the steering wheel, it could be a skill thing still. It would just be over-boosting the current calculated wheel speed, but it could be used to corner in fabulous ways!!

[mzso]

The problem with somehow restricting braking force, is that it’s not on the edge of locking up anymore, there is no skill involved. Bit like ABS. You just flip the brake switch and wait until you can turn in. Until software is so good that a BBW system has as much feel as a normal system, it’s not an option for F1

Feel is irrelevant.
Your analogy to ABS doesn't make sense. Only ABS is ABS, with less braking force the point of locking up is only shifted towards lower speeds when the downforce is less.

[Jolle]

The problem with somehow restricting braking force, is that it’s not on the edge of locking up anymore, there is no skill involved. Bit like ABS. You just flip the brake switch and wait until you can turn in. Until software is so good that a BBW system has as much feel as a normal system, it’s not an option for F1

Feel is irrelevant.
Your analogy to ABS doesn't make sense. Only ABS is ABS, with less braking force the point of locking up is only shifted towards lower speeds when the downforce is less.

If you can’t lock up the brakes because grip will be higher then the braking force, there wouldn’t be any skill in it anymore. You can just brake 100% all the time. Like having a motorcycle with pushbike brakes.

[mzso]

If you can’t lock up the brakes because grip will be higher then the braking force, there wouldn’t be any skill in it anymore. You can just brake 100% all the time. Like having a motorcycle with pushbike brakes.

You obviously didn't read and interpret my comment.

[NL_Fer]

I am trying some calculations.

Current ICE are at least 600kw, combined with 120kw mgu-K. K is available for all the full throttle parts of a lap, lets assume this at 60s for an average lap. A total of 7,2MJ of which 2MJ from mgu-K braking, 5,2MJ of Mgu-H exhaust recovery.

If we would reduce the ICE to an in-line 3 with 50% fuel flow but increase the efficiency with 20% (50 -> 60% BTE). The result is 0.50 x 1,20 x 600 = 360kw ICE. To compensate, keep the same total power, the mgu-K has to increase to 360kw. Exhaust recovery will also decrease with 0.50 x 1.20 x 5,2MJ = 3,12MJ.

Total available recovered energy is 3,12 (exhaust) + 2 (brake) = 5,12MJ. With a 360kw Mgu-K, this results in only 5120 / 360 = 14.2s K available per lap. That is allot less than we have now.

If we would reduce the ICE to a V4 with 66% fuel flow, also increased efficiency with 20%. The result is 0.66 x 1.20 x 600 = 475kw ICE. To compensate, keep current total power, the mgu-K has to increase to 245kw. Exhaust recovery will decrease to 0.66 x 1.20 x 5,2MJ = 4.1MJ.

Total recovered energy is now 4.1 (exhaust) + 2 (brake) = 6.1MJ. With a 245kw mgu-K, this results in 6100 / 245 = 24.9s available per lap. Still less, but this is a workable amount. If we would add another 2MJ of the front brake recovery, we would have 8100 / 245 = 33s of available K.

So to me a 33% smaller ICE seems much more realistic, than a 50% smaller ICE.

[godlameroso]

I am trying some calculations.

Current ICE are at least 600kw, combined with 120kw mgu-K. K is available for all the full throttle parts of a lap, lets assume this at 60s for an average lap. A total of 7,2MJ of which 2MJ from mgu-K braking, 5,2MJ of Mgu-H exhaust recovery.

If we would reduce the ICE to an in-line 3 with 50% fuel flow but increase the efficiency with 20% (50 -> 60% BTE). The result is 0.50 x 1,20 x 600 = 360kw ICE. To compensate, keep the same total power, the mgu-K has to increase to 360kw. Exhaust recovery will also decrease with 0.50 x 1.20 x 5,2MJ = 3,12MJ.

Total available recovered energy is 3,12 (exhaust) + 2 (brake) = 5,12MJ. With a 360kw Mgu-K, this results in only 5120 / 360 = 14.2s K available per lap. That is allot less than we have now.

If we would reduce the ICE to a V4 with 66% fuel flow, also increased efficiency with 20%. The result is 0.66 x 1.20 x 600 = 475kw ICE. To compensate, keep current total power, the mgu-K has to increase to 245kw. Exhaust recovery will decrease to 0.66 x 1.20 x 5,2MJ = 4.1MJ.

Total recovered energy is now 4.1 (exhaust) + 2 (brake) = 6.1MJ. With a 245kw mgu-K, this results in 6100 / 245 = 24.9s available per lap. Still less, but this is a workable amount. If we would add another 2MJ of the front brake recovery, we would have 8100 / 245 = 33s of available K.

So to me a 33% smaller ICE seems much more realistic, than a 50% smaller ICE.

V or I4 ? V engine is probably better for packaging.

[gruntguru]

No. I want to now what power an engine needs to run at continuously to serve the energy generation needs. Which would obviously be the optimization target, efficiency wise. In a series hybrid you'd want to continuously run the engine at peak efficiency, obviously.
I wonder what would be the most efficient combustion engine. (I was mocked for mentioning gas turbines, among others..)

Under current rules there is 100 kg of fuel and we can assume the heating value is about 45 MJ/kg so there is a maximum of about 4500 MJ of energy available. If we assume a conversion efficiency of 50% and a race duration of 2 hours, the average engine output is 312 kW.

[gruntguru]

V or I4 ? V engine is probably better for packaging.

Also probably better for transitioning from current chassis which are designed around a V6.

[Big Tea]

V or I4 ? V engine is probably better for packaging.

Also probably better for transitioning from current chassis which are designed around a V6.

What would be the disadvantage of a 3 cyl laying horizontally, either longitudinally as now or transverse?

A L3 cyl is also 'half' a current engine size, and less cooling requirement. Would it be ridiculously inefficient to make it aircooled?

Thinking of all the saved radiator space

[Jolle]

With a turbo engine, displacement or the amount of cilinders isn’t really important for performance. As for durability (and therefore cost saving) I assume a V6 1.6 is less complicated then a 1.0 v4 or something.

[gruntguru]

V or I4 ? V engine is probably better for packaging.

Also probably better for transitioning from current chassis which are designed around a V6.

What would be the disadvantage of a 3 cyl laying horizontally, either longitudinally as now or transverse?

A L3 cyl is also 'half' a current engine size, and less cooling requirement. Would it be ridiculously inefficient to make it aircooled?

Thinking of all the saved radiator space

I have a preference for L3 over V4 myself but that is aside from the point I was making.