2025/2026 Hybrid Powerunit speculation

All that has to do with the power train, gearbox, clutch, fuels and lubricants, etc. Generally the mechanical side of Formula One.
Tommy Cookers
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Re: 2025/2026 Hybrid Powerunit speculation

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gruntguru wrote:
Sun Sep 18, 2022 10:46 pm
(The engines will have a significant positive pressure differential (MAP>EAP) under the new rules.)
why ?

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Holm86
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Re: 2025/2026 Hybrid Powerunit speculation

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Tommy Cookers wrote:
Mon Sep 19, 2022 2:50 pm
gruntguru wrote:
Sun Sep 18, 2022 10:46 pm
(The engines will have a significant positive pressure differential (MAP>EAP) under the new rules.)
why ?
He probably means the turbine side of the turbo will be smaller than currently, to aid the responsiveness of the Turbo, now the MGU-H isn't there anymore. This will increase exhaust back pressure. I'm wondering how much of that they can negate with the waste gate.

Could it perhaps even be beneficial to run the engine at higher RPM? As the airflow through the engine should be constant above 10.500 rpm, it means every rpm above that, you need less boost, so perhaps running at higher RPM with the waste gate fully open would give better performance due to less exhaust back pressure??

gruntguru
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Re: 2025/2026 Hybrid Powerunit speculation

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Tommy Cookers wrote:
Mon Sep 19, 2022 2:50 pm
gruntguru wrote:
Sun Sep 18, 2022 10:46 pm
(The engines will have a significant positive pressure differential (MAP>EAP) under the new rules.)
why ?
Reduced backpressure = better ICE efficiency and power. There is no longer any advantage in maximising turbine output. They will size the turbine to generate enough power to drive the compressor with the lowest possible backpressure. This also means targeting minimum wastegate flow.
je suis charlie

wuzak
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Re: 2025/2026 Hybrid Powerunit speculation

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Holm86 wrote:
Tue Sep 20, 2022 12:27 am
He probably means the turbine side of the turbo will be smaller than currently, to aid the responsiveness of the Turbo, now the MGU-H isn't there anymore. This will increase exhaust back pressure. I'm wondering how much of that they can negate with the waste gate.
They may well be smaller than now, but they won't be small.

Some dimensions for the turbo are controlled, such as one of the dimensions for the turbine and compressor wheel diameters.

noname
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Re: 2025/2026 Hybrid Powerunit speculation

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Holm86 wrote:
Tue Sep 20, 2022 12:27 am
Tommy Cookers wrote:
Mon Sep 19, 2022 2:50 pm
gruntguru wrote:
Sun Sep 18, 2022 10:46 pm
(The engines will have a significant positive pressure differential (MAP>EAP) under the new rules.)
why ?
He probably means the turbine side of the turbo will be smaller than currently, to aid the responsiveness of the Turbo, now the MGU-H isn't there anymore. This will increase exhaust back pressure. I'm wondering how much of that they can negate with the waste gate.

Could it perhaps even be beneficial to run the engine at higher RPM? As the airflow through the engine should be constant above 10.500 rpm, it means every rpm above that, you need less boost, so perhaps running at higher RPM with the waste gate fully open would give better performance due to less exhaust back pressure??
Turbine is sized by the mass flow it has to deal with. Smaller turbine will have reduced flow capacity, and this may negatively impact power generated by ICE. It would just choke the engine.

It could be smaller if they would go for lower Lambda.

To improve transient response without hurting flow capacity you can i.e. use mixed flow turbine wheel. This approach was already used in some F1 turbos of the current era, could be there woule be more radical solutions.

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Big Tea
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Re: 2025/2026 Hybrid Powerunit speculation

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Some while back, due to 'emission laws' the self-shifting automatics suffered due to a little device that held the 'throttle' open fractionally not allowing the revs to drop quickly. Would something similar be useful with the new engines? hold the revs up but open wastegates and cut fuel? Could RPM stay high(er) and power output be controlled by fuel feed?

Or is this famous 'turbo lag' a thing of the media? Things have advanced much from the old days of turbo
When arguing with a fool, be sure the other person is not doing the same thing.

noname
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Re: 2025/2026 Hybrid Powerunit speculation

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Big Tea wrote:
Tue Sep 20, 2022 10:05 am
Some while back, due to 'emission laws' the self-shifting automatics suffered due to a little device that held the 'throttle' open fractionally not allowing the revs to drop quickly. Would something similar be useful with the new engines? hold the revs up but open wastegates and cut fuel? Could RPM stay high(er) and power output be controlled by fuel feed?

Or is this famous 'turbo lag' a thing of the media? Things have advanced much from the old days of turbo
When development of todays' POs started teams were evaluating turbo lag in simulators. They found out their test drivers were able to adapt to even the most ridiculous amount of lag within few laps.

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djos
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Re: 2025/2026 Hybrid Powerunit speculation

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Senna was famous for being able to keep the turbo spooled up with his unique style.

The impossible often has a kind of integrity which the merely improbable lacks.

Tommy Cookers
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Re: 2025/2026 Hybrid Powerunit speculation

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Holm86 wrote:
Tue Sep 20, 2022 12:27 am
gruntguru wrote:
Sun Sep 18, 2022 10:46 pm
(The engines will have a significant positive pressure differential (MAP>EAP) under the new rules.)
Could it perhaps even be beneficial to run the engine at higher RPM? As the airflow through the engine should be constant above 10.500 rpm, it means every rpm above that, you need less boost, so perhaps running at higher RPM with the waste gate fully open would give better performance due to less exhaust back pressure??
a given positive pressure differential does less with Miller cycle - does F1 currently have Miller cycle ?

the fuel energy rate will be c.75% of that current
boost can be much lower even sticking to 10500 rpm (15000 would be close to NA conditions)
but Miller cycle needs more boost than non-Miller - though not more compressor power ?

NL_Fer
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Re: 2025/2026 Hybrid Powerunit speculation

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Big Tea wrote:
Tue Sep 20, 2022 10:05 am
Some while back, due to 'emission laws' the self-shifting automatics suffered due to a little device that held the 'throttle' open fractionally not allowing the revs to drop quickly. Would something similar be useful with the new engines? hold the revs up but open wastegates and cut fuel? Could RPM stay high(er) and power output be controlled by fuel feed?

Or is this famous 'turbo lag' a thing of the media? Things have advanced much from the old days of turbo
I doubt the even close the throttle on upshift, just retard timing for a few ignitions will give a few ms of reduced torque output, but keep the exhaust flowing. The reduced torque is enough to shift up.

gruntguru
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Re: 2025/2026 Hybrid Powerunit speculation

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NL_Fer wrote:
Tue Sep 20, 2022 9:03 pm
Big Tea wrote:
Tue Sep 20, 2022 10:05 am
Some while back, due to 'emission laws' the self-shifting automatics suffered due to a little device that held the 'throttle' open fractionally not allowing the revs to drop quickly. Would something similar be useful with the new engines? hold the revs up but open wastegates and cut fuel? Could RPM stay high(er) and power output be controlled by fuel feed?

Or is this famous 'turbo lag' a thing of the media? Things have advanced much from the old days of turbo
I doubt the even close the throttle on upshift, just retard timing for a few ignitions will give a few ms of reduced torque output, but keep the exhaust flowing. The reduced torque is enough to shift up.
That would waste fuel.
je suis charlie

NL_Fer
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Re: 2025/2026 Hybrid Powerunit speculation

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gruntguru wrote:
Wed Sep 21, 2022 2:27 am
NL_Fer wrote:
Tue Sep 20, 2022 9:03 pm
Big Tea wrote:
Tue Sep 20, 2022 10:05 am
Some while back, due to 'emission laws' the self-shifting automatics suffered due to a little device that held the 'throttle' open fractionally not allowing the revs to drop quickly. Would something similar be useful with the new engines? hold the revs up but open wastegates and cut fuel? Could RPM stay high(er) and power output be controlled by fuel feed?

Or is this famous 'turbo lag' a thing of the media? Things have advanced much from the old days of turbo
I doubt the even close the throttle on upshift, just retard timing for a few ignitions will give a few ms of reduced torque output, but keep the exhaust flowing. The reduced torque is enough to shift up.
That would waste fuel.
Than why not skip a few injections or run on 3-4 cilinders for a few rotations? Everything is better than closing the throttle I think.

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Zynerji
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Re: 2025/2026 Hybrid Powerunit speculation

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NL_Fer wrote:
Thu Sep 22, 2022 5:43 pm
gruntguru wrote:
Wed Sep 21, 2022 2:27 am
NL_Fer wrote:
Tue Sep 20, 2022 9:03 pm
I doubt the even close the throttle on upshift, just retard timing for a few ignitions will give a few ms of reduced torque output, but keep the exhaust flowing. The reduced torque is enough to shift up.
That would waste fuel.
Than why not skip a few injections or run on 3-4 cilinders for a few rotations? Everything is better than closing the throttle I think.
Isn't that breaking traction control rules?🤔

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Big Tea
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Re: 2025/2026 Hybrid Powerunit speculation

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Zynerji wrote:
Thu Sep 22, 2022 6:35 pm
NL_Fer wrote:
Thu Sep 22, 2022 5:43 pm
gruntguru wrote:
Wed Sep 21, 2022 2:27 am
That would waste fuel.
Than why not skip a few injections or run on 3-4 cilinders for a few rotations? Everything is better than closing the throttle I think.
Isn't that breaking traction control rules?🤔
Would that not depend on how it was 'triggered'? If it was on the shift not on (lack of) demand would it not be ok?
When arguing with a fool, be sure the other person is not doing the same thing.

NL_Fer
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Re: 2025/2026 Hybrid Powerunit speculation

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Zynerji wrote:
Thu Sep 22, 2022 6:35 pm
NL_Fer wrote:
Thu Sep 22, 2022 5:43 pm
gruntguru wrote:
Wed Sep 21, 2022 2:27 am
That would waste fuel.
Than why not skip a few injections or run on 3-4 cilinders for a few rotations? Everything is better than closing the throttle I think.
Isn't that breaking traction control rules?🤔
5.6 Power unit torque demand
5.6.1 The only means by which the driver may control acceleration torque to the driven wheels is
via a single foot (accelerator) pedal mounted inside the survival cell.
Don’t think that cutting a few injections on shift will break this rule. Also cutting or retarding ignition has been the default action on upshift since the begin of semi-automatic gearboxes.