2025/2026 Hybrid Powerunit speculation

[gruntguru]

at the base level, intercoolers are removing work (heat) that the system is putting into it via the compressor so they do represent net loss in efficiency

in road cars I know they go a long way to reducing the NOx emissions due to reducing the inlet charge temperature

also, they allow for a denser air charge so you can react more fuel to get more power, but not necessarily more efficiency

What Tommy's saying above is with Direct Injection fuel is introduced at the last possible moment and is not a factor in cooling the charge air like it is for port injection

Well, it really isn't that simple.
Let us start and just look at the system before the air enters the cylinder. Yes technically an intercooler removes energy from the system, but the question is how much oxygen you need. By removing heat, you get more oxygen per volume at the same pressure. Or with other words, an intercooler allows you to run with lower boost pressure to get the same amount of oxygen into the cylinder. More boostpressure means more work for the turbo which means even more heat and so on. So overall, an intercooler makes the charge cycle more efficient. The whole point of any charge system is to get more oxygen into the cylinder. You don't need more pressure, that's just an unavoidable side effect.

It really doesn't matter if you have port- or direct injection. The evaporative cooling effect happens all the same. Direct injection can't beat physics and liquids don't burn.

But overall, it really is a question of how high the thermal limits are set. If you don't remove the heat of the compressed air before it reaches the cylinder, the heat will simply end up somewhere else. Which means higher cylinder wall, piston crown, exhaust valve and so on temperature. If all these components can easely deal with that, sure run without an intercooler. But in most cases, you will run into thermal problems somewhere.

Charge air cooling adds to power - if you have unlimited fuel to burn.
Charge air cooling reduces cycle efficiency.

The benefits of fuel evaporative cooling vary depending on whether the evaporation occurs:
a. In the intake system before the valve
b. In cylinder but prior to IVC
c. In cylinder, after IVC but before TDC. . . and at what point in the compression stroke it occurs.

So there is a difference between DI and PFI.

[wuzak]

Will this be lowest ICE power since the cosworth DFV?

Yes.

So overall is this going to be somewhere near to the 919 Evo or less powerful?

Less powerful.

919 Evo had ~710hp from ICE + 430hp MGUKs, bigger battery, no limits on deployment or recovery.

Also, 919 and 919 EVO have MGUH.


Closer to the 919.
ICE: 500hp
MGUK: 400hp

F1 2026:
ICE: ~ 550hp
MGUK: 470hp

[FW17]

With only recovery from the rear, we are sure to see some totally different strategy towards recovery. This is going to completely change the mechanics of the car and the way drivers turn into corners.

The usual load transfer to the front/more front braking will be gone, max braking at the rear at initial stage with front brakes modulated for stability and bias moving forward towards the latter half. Almost a complete opposite to what we are used to seeing. The stability under braking will be worked on by some mechanical elements as EBS probably is not allowed.

This recovery game is going to be built into the chassis, and anyone missing the bus is going to be behind for years. Chassis and hybrid recovery is going to have to be baked into the car, i.e if you are not a works team, you are screwed.

[wuzak]

A lot of recovery will be done by burning fuel.

If the fuel burning per lap is 30kg as suggested by Symonds, the energy recovered through burning fuel is:

Fuel energy for a race 41MJ/kg * 30kg = 1230MJ

Assume thermal efficiency of 50%
Energy from ICE for race = 615MJ

90% efficiency to store energy in battery
90% * 615 = 553.5MJ per race

For a 50 lap race that is 553.5MJ/50 = 11.07MJ per lap > 9MJ allowed

For 60 lap race, 553.5MJ/60 = 9.225MJ per laps > 9MJ allowed.

So the 30kg estimate would seem to have been an exaggeration.

For the lower end fuel energy density (38MJ/kg) the numbers are:
Fuel energy for race 38MJ/kg * 30kg = 1140MJ
Energy from ICE for race = 570MJ
Storage 90% * 570 = 513MJ per race
Per lap 10.26MJ (50 laps)
8.55MJ (60 laps)

[wuzak]

Reversing that, how much fuel would we need?

Assume average 15s braking @ 350kW per lap => 5.25MJ/lap
Storage Efficiency @ 90%, stored brake energy per lap = 4.725MJ/lap
Required energy to get from fuel burning = 9MJ - 4.725MJ = 4.275MJ

Required energy to be recovered before storage = 4.275MJ/90% = 4.75MJ/lap

For a 60 lap race, total = 60 * 4.75 = 285MJ

50% thermal efficiency => fuel energy required = 570MJ/race

Fuel energy density 38MJ/kg (worst case)
Fuel required = 570MJ / 38MJ/kg = 15kg

[FW17]

Reversing that, how much fuel would we need?

Assume average 15s braking @ 350kW per lap => 5.25MJ/lap
Storage Efficiency @ 90%, stored brake energy per lap = 4.725MJ/lap
Required energy to get from fuel burning = 9MJ - 4.725MJ = 4.275MJ

Required energy to be recovered before storage = 4.275MJ/90% = 4.75MJ/lap

For a 60 lap race, total = 60 * 4.75 = 285MJ

50% thermal efficiency => fuel energy required = 570MJ/race

Fuel energy density 38MJ/kg (worst case)
Fuel required = 570MJ / 38MJ/kg = 15kg

How can they burn fuel? Will it be lift and coast at max engine power with the clutch engaged so that all energy is captured by the MGU? That would be 14 sec of lift and coast?

[wuzak]

Reversing that, how much fuel would we need?

Assume average 15s braking @ 350kW per lap => 5.25MJ/lap
Storage Efficiency @ 90%, stored brake energy per lap = 4.725MJ/lap
Required energy to get from fuel burning = 9MJ - 4.725MJ = 4.275MJ

Required energy to be recovered before storage = 4.275MJ/90% = 4.75MJ/lap

For a 60 lap race, total = 60 * 4.75 = 285MJ

50% thermal efficiency => fuel energy required = 570MJ/race

Fuel energy density 38MJ/kg (worst case)
Fuel required = 570MJ / 38MJ/kg = 15kg

How can they burn fuel? Will it be lift and coast at max engine power with the clutch engaged so that all energy is captured by the MGU? That would be 14 sec of lift and coast?

No, it will be full throttle at the end of the straights with regen - max 100kW.

Plus part throttle where power demanded is less than ICE maximum output at that rpm. The MGUK will recover the difference between ICE output and power demanded.

eg. if the driver is asking for 350kW and the ICE can deliver 400kW at that rpm, the MGUK can recover 50kW.

It may mean that drivers will take some corners in lower gears than otherwise, to keep the ICE in the best rpm for power and efficiency while allowing for energy recovery.

[wuzak]

Sorry, there will be lift and coast as well, to extend the braking zone.

So, driving down straight, PU power is reduced as car gets above 300km/h. At some point along straight it is reduced to allow for regen at 100kW.

Then will lift and coast before actual braking zone, recovering 350kW at this point.

Lift and coast isn't really fuel burning, as the driver power demand will be 0.

[FW17]

Sorry, there will be lift and coast as well, to extend the braking zone.

So, driving down straight, PU power is reduced as car gets above 300km/h. At some point along straight it is reduced to allow for regen at 100kW.

Then will lift and coast before actual braking zone, recovering 350kW at this point.

Lift and coast isn't really fuel burning, as the driver power demand will be 0.

It will actually not be lift as driver will have to be on the throttle. Wheels has to be disconnected from the engine for it to recharge. Repeated use of clutch would require lot beefier clutch.

Even then, 10 sec or more of this is implausible.

[NL_Fer]

With only 500bhp from the ICE I don’t see how they can burn 30kg for ICE->MGUK regeneration. It will be just a few seconds after corner exit and the power demand will exceed that 500bhp.

[saviour stivala]

Sorry, there will be lift and coast as well, to extend the braking zone.

So, driving down straight, PU power is reduced as car gets above 300km/h. At some point along straight it is reduced to allow for regen at 100kW.

Then will lift and coast before actual braking zone, recovering 350kW at this point.

Lift and coast isn't really fuel burning, as the driver power demand will be 0.

It will actually not be lift as driver will have to be on the throttle. Wheels has to be disconnected from the engine for it to recharge. Repeated use of clutch would require lot beefier clutch.

Even then, 10 sec or more of this is implausible.

How will recharge be possible if wheels are disconnected from the engine?.

[wuzak]

Sorry, there will be lift and coast as well, to extend the braking zone.

So, driving down straight, PU power is reduced as car gets above 300km/h. At some point along straight it is reduced to allow for regen at 100kW.

Then will lift and coast before actual braking zone, recovering 350kW at this point.

Lift and coast isn't really fuel burning, as the driver power demand will be 0.

It will actually not be lift as driver will have to be on the throttle. Wheels has to be disconnected from the engine for it to recharge. Repeated use of clutch would require lot beefier clutch.

Even then, 10 sec or more of this is implausible.

MGUK is connected to the crankshaft.

So when the driver lifts off before braking the MGUK can recover 350kW from the rear wheels to slow down the car before the braking starts.

I think you're talking about isolating the engine from the rear wheels, and then using the MGUK to load the ICE to 350kW.

You would then have to reconnect the engine to the rear wheels to recover energy from braking, while also reducing the ICE power.

I suppose that the ICE can also produce power in braking zones where the full 350kW recovery would otherwise be impossible.

[Tommy Cookers]

With only recovery from the rear .... is going to completely change the mechanics of the car and the way drivers turn into corners.
The usual load transfer to the front/more front braking will be gone .....

the rear tyres have demands on their grip from friction brake torque and regenerative (braking) torque acting together
in principle nothing will change
ok as grip falls with speed 2026 350 kW's worth of regenerative torque will be unavailable sooner than 2025 120 kW's

if 2026 has less drag on straights it has less DF and braking torque - so 350 kW's worth will be available for a longer time
(unless they revert to high drag high DF at the braking point)

[wuzak]

if 2026 has less drag on straights it has less DF and braking torque - so 350 kW's worth will be available for a longer time
(unless they revert to high drag high DF at the braking point)

I believe that is the whole point of the active aero.

Reduce drag on straights but have downforce for corners.

[Tommy Cookers]

if 2026 has less drag on straights it has less DF and braking torque - so 350 kW's worth will be available for a longer time
(unless they revert to high drag high DF at the braking point)

I believe that is the whole point of the active aero.
Reduce drag on straights but have downforce for corners.

downforce for corners or downforce for corners and downforce for braking ?