2026 Hybrid Powerunits

[wuzak]

@Wuzak - under the rules is it possible they can run the engine in generator mode with the car stationary? What fuel flow would be available? They could certainly do this with radically retarded timing to generate hot exhaust gas.

It seems so.

C5.2.12 During a standing start from the grid the MGU-K may only be used once the car has reached 50 km/h.
C5.2.13 The amount of stored energy in the ES may not be increased by more than 100kJ whilst the car is stationary in the garage during the Sprint Qualifying and Qualifying Sessions.

C5.2.19 When the car is stationary on the grid prior to a standing start the MGU-K torque may only be negative (i.e. charging the ES) except for torque requested by an MGU-K active damping strategy whose sole purpose is to protect the MGU-K Mechanical Transmission.
C5.2.20 No off-board ES charger of any kind may be used whilst the car is in the pitlane

It looks to be specifically allowed!

[vorticism]

Was thinking there must be a clause like that.

I guess the long spooling time means they can’t use the K to speed up the engine while it’s declutched on the grid.

This gives us our 5 sec (or more) spool time. But how good would it have been to see all 20 cars (22 if counting Cadillac) mega blip the ICE with the now-500hp MGUK, late fuel, late spark, and throw a flame for a couple seconds right before the launch...

Is there a correlating specification for what ICE speed (& thus fuel qty) and/or MGUK regen power can be used during declutch/idle/standstill. A sidenote is that this would go some way to telling us how much heat these passive cooling systems can soak up at a standstill.

If cold blowing is re-used in 2026, perhaps this video could give us an idea of what that might sound like?

Maybe. Solve for:
-Can the ICE deliver sufficient gas flow during engine braking to the turbine and at what RPM, to prevent lag
-With or without combustion heat?
-What if any limits are there to injection timing (RBPT interview suggested this exists)
-Would such open throttle engine braking anti-lag be less taxing upon the ES
-Is any of this bad for ICE reliability

Fit to:
-1 spark rule

[wuzak]

Was thinking there must be a clause like that.

I guess the long spooling time means they can’t use the K to speed up the engine while it’s declutched on the grid.

This gives us our 5 sec (or more) spool time. But how good would it have been to see all 20 cars (22 if counting Cadillac) mega blip the ICE with the now-500hp MGUK, late fuel, late spark, and throw a flame for a couple seconds right before the launch...

Is there a correlating specification for what ICE speed (& thus fuel qty) and/or MGUK regen power can be used during declutch/idle/standstill. A sidenote is that this would go some way to telling us how much heat these passive cooling systems can soak up at a standstill.

I would imagine the part throttle fuel flow rules would determine the amount that could be recovered.

Also, the net power of the PU would be what the clutch can hold for preloading at the start.

The launch would, therefore, not be the increse in power from the ICE, at least not completely, but the reduction of recovery.

[michl420]

As I understand this, this is a possible race start procedure?!:
1 red light: ice up to rpm (10500?)
2 red light: MGUK start regeneration with allowed power (200kw?, 350kw?), batterie must be not full
lights out: MGUK reduces regeneration like driver demand.
This would give full power very early, and a (mostly) electric controlled start (if it is desired).

This preload had also nothing to do with the driveshaft cluch, because ICE and MGUK are both located "before" it.

[saviour stivala]

As I understand this, this is a possible race start procedure?!:
1 red light: ice up to rpm (10500?)
2 red light: MGUK start regeneration with allowed power (200kw?, 350kw?), batterie must be not full
lights out: MGUK reduces regeneration like driver demand.
This would give full power very early, and a (mostly) electric controlled start (if it is desired).

This preload had also nothing to do with the driveshaft cluch, because ICE and MGUK are both located "before" it.

MGU-K regeneration is the process of recovering energy during braking. This process is not compatible with race start, which is about using energy not recovering it.

[gruntguru]

@Wuzak - under the rules is it possible they can run the engine in generator mode with the car stationary? What fuel flow would be available? They could certainly do this with radically retarded timing to generate hot exhaust gas.

It seems so. . . .
C5.2.19 When the car is stationary on the grid prior to a standing start the MGU-K torque may only be negative (i.e. charging the ES) except for torque requested by an MGU-K active damping strategy whose sole purpose is to protect the MGU-K Mechanical Transmission. . . .
It looks to be specifically allowed!

As to the fuel flow allowed during this pre-launch spool-up phase, do you think it will be just the 869 MJ/hr from 5.4.5 below?
5.4.5 At partial load, the fuel energy flow must not exceed the limit curve defined below:
• EF (MJ/h) = 380 when the engine power is equal to or below -50kW
• EF (MJ/h) = 9.78 x engine power (kW) + 869 when the engine power is above -50kW
That might be enough if combined with late spark timing.

[wuzak]

I would think more, as they don't sit waiting for the lights to go out with 0kW power.

They hold the clutch at thr bite point and load the engine against the brakes.

If that was 50kW, the fuel flow would be over 50% greater.

[saviour stivala]

The regulations will not allow the engine to be run as a generator in stationary mode. Running the engine as a generator is a form of energy recovery, but it can only happen while the car is in motion, not when the car is stationary.

[mzso]

Multiple tanks is not allowed. There isn't a limit in tank size in the new regs. Just a flow rate restriction. I think my math says 93L/hr ish. You can do the math for a 1.5hr race.

I wonder if it's viable to have different fuel tank sizes and variable packaging.

[mzso]

What I was getting at was, if it was permitted to use the 500 hp MGUK to increase the crankshaft speed of the 500 hp ICE beyond what the ICE itself can provide, then this should help spool up the turbine more quickly. But as the video alluded to, it takes 5 seconds to spool--does this mean the K can’t be used during idle? There are limits, discussed earlier in this topic, about what the MGUK can do independent of pedal position. It's too bad they can't use two accelerator pedals! How much fun would that be. Fiddle-throttle has a nice ring to it.

As for relying on the MGUK & ES alone to compensate for lag, you’d be leaving performance on the table if there is a way to overcome it by another means.

Isn't that what it always does when they use it for power deployment? Add electric power and the ICE speeds up as well.

[mzso]

Fortunately the ICE can make near full power with nowhere-near full boost - the extra boost is needed to maximise TE and eke out the last handful of ponies.

This goes against my understanding of forced induction.

[diffuser]

Multiple tanks is not allowed. There isn't a limit in tank size in the new regs. Just a flow rate restriction. I think my math says 93L/hr ish. You can do the math for a 1.5hr race.

I wonder if it's viable to have different fuel tank sizes and variable packaging.

The positioning is VERY restrictive. What I remember reading... it just about sounded like "you got to put it here". The tank itself is a bladder so it grows and shrinks with the amount of fuel in it. It's tall and slender. Has multiple vertical compartments with fuel being able to go down a compartment but not back up. It's probably been behind the driver for the last 30 years, if not more.

[mzso]

Multiple tanks is not allowed. There isn't a limit in tank size in the new regs. Just a flow rate restriction. I think my math says 93L/hr ish. You can do the math for a 1.5hr race.

I wonder if it's viable to have different fuel tank sizes and variable packaging.

The positioning is VERY restrictive. What I remember reading... it just about sounded like "you got to put it here". The tank itself is a bladder so it grows and shrinks with the amount of fuel in it. It's tall and slender. Has multiple compartments with fuel being able to go down a compartment but not back up. It's probably been behind the driver for the last 30 years, if not more.

I meant package stuff around it when you need a larger size and different aero cover.

[diffuser]

I wonder if it's viable to have different fuel tank sizes and variable packaging.

The positioning is VERY restrictive. What I remember reading... it just about sounded like "you got to put it here". The tank itself is a bladder so it grows and shrinks with the amount of fuel in it. It's tall and slender. Has multiple compartments with fuel being able to go down a compartment but not back up. It's probably been behind the driver for the last 30 years, if not more.

I meant package stuff around it when you need a larger size and different aero cover.

I think the space is made there as part of the frame, the ICE is part of the frame. It could only be changed at great cost.

[wuzak]

As I understand this, this is a possible race start procedure?!:
1 red light: ice up to rpm (10500?)
2 red light: MGUK start regeneration with allowed power (200kw?, 350kw?), batterie must be not full
lights out: MGUK reduces regeneration like driver demand.
This would give full power very early, and a (mostly) electric controlled start (if it is desired).

This preload had also nothing to do with the driveshaft cluch, because ICE and MGUK are both located "before" it.

MGU-K regeneration is the process of recovering energy during braking. This process is not compatible with race start, which is about using energy not recovering it.

The regulations will not allow the engine to be run as a generator in stationary mode. Running the engine as a generator is a form of energy recovery, but it can only happen while the car is in motion, not when the car is stationary.

Please explain the meaning of the following regulation:

C5.2.19 When the car is stationary on the grid prior to a standing start the MGU-K torque may only be negative (i.e. charging the ES) except for torque requested by an MGU-K active damping strategy whose sole purpose is to protect the MGU-K Mechanical Transmission.