2025/2026 Hybrid Powerunit speculation

[saviour stivala]

''So 2mj is recovered by MGU-H while driving with open waste-gate/s'' While driving with open waste-gates the MGU-H is in motoring mode and while motoring it cannot also harvest.

[yelistener]

You wouldn't happen to have ones for Spa and Azerbijan?

Spa is zero full boost. Baku is like 0.5s at the exit of the last real corner. They're too little so it's not worth making a video.

It can be a bit different with other teams. Some cars' exhaust mic don't give away the full boost sound, so we can't know.

Thanks.

I guess they have sections that are full throttle for so long that there isn't enough energy to do full boost.

They probably had full boost in Spa quali pre-2017. I remember that Honda magazine showed that in Spain the full boost happened in some part of the track in 2016 where there was none in 2017, and the difference is not exactly tiny. This could indicate recovering energy also happens during overrun (mid-corner no braking), or partial throttle at corner exit.

[johnny comelately]

Just a query re waste gate opening
If audio analysis is being used is it possible that the change in pitch could be from the extra load coming on from the G being activated?

[NL_Fer]

''So 2mj is recovered by MGU-H while driving with open waste-gate/s'' While driving with open waste-gates the MGU-H is in motoring mode and while motoring it cannot also harvest.

Could be yes.

Actually there is no indication there is 4MJ recovery/harvest and since this a qualifying lap, probably there isn’t. On a Q lap they drain the battery to end reach the finish line with 0% Soc for the ES.

But 4MJ is not enough for 28.5s of Deployment for both ES to K and ES to H driving the turbine. So probably there is still 1-2MJ of recovery done OR the turbocharger can run on exhaust energy with open wastegates, and the MGU-H is idle or in low power harvesting or motoring.

There is no reason to assume the waste-gates are simple on-off, but 0-100% controllable open close. Just like on our turbocharged street car.

[saviour stivala]

It, the turbocharger turbine used in F1 being a pressure type of turbine + the waste-gate/s used are designed to bypass exhaust gases from the turbine, when waste-gate/s are open the turbine is simply riding along on the turbo shaft while the whole thing is motored by the 'H', which in turn is sharing 'ES' power with 'K'. (electric supercharging mode/free load mode).

[yelistener]

Mercedes actually posted a video on youtube including a small part explaining this wastegate open mode. They call it "AMG turbo mode", which Hywel Thomas said MGU-H was being powered in that mode and not harvesting energy.

Explanation starting at 10:36

[johnny comelately]

Mercedes actually posted a video on youtube including a small part explaining this wastegate open mode. They call it "AMG turbo mode", which Hywel Thomas said MGU-H was being powered in that mode and not harvesting energy.

Explanation starting at 10:36
https://youtu.be/RwwUOYTbyfs?t=635

OK that makes sense now (takes a while)
waste gate open compressor run e mode

[Tommy Cookers]

It, the turbocharger turbine used in F1 being a pressure type of turbine + the waste-gate/s used are designed to bypass exhaust gases from the turbine, when waste-gate/s are open the turbine is simply riding along on the turbo shaft while the whole thing is motored by the 'H', which in turn is sharing 'ES' power with 'K'. (electric supercharging mode/free load mode).

the above is incorrect ......
unless the exhaust gas is entirely diverted away from the turbine and the main exhaust pipe

but .....
the turbine actually gets 1 atm exhaust so kinetic pulses/waves still (quite weakly) power the turbine and compressor
this power recovery-without-backpressure is the so-called blowdown recovery
here it somewhat reduces the amount of ES energy needed by the MGU-H in driving the compressor
so increasing the available duration of this ('electric supercharge') running mode

there is no evidence that the turbine responds only to mean exhaust pressure (is unresponsive to kinetic 'pulses')
clearly all 4 makes of ICE have exhaust manifolds designed to encourage these pulses
and the pulses are anyway relatively stronger in 1 atm exhaust than in the main ('backpressure') running mode


fortunately for us there is no MGU-H and so no 'electric supercharge' in 2026 hybrid F1

[saviour stivala]

Spa is zero full boost. Baku is like 0.5s at the exit of the last real corner. They're too little so it's not worth making a video.

It can be a bit different with other teams. Some cars' exhaust mic don't give away the full boost sound, so we can't know.

Thanks.

I guess they have sections that are full throttle for so long that there isn't enough energy to do full boost.

They probably had full boost in Spa quali pre-2017. I remember that Honda magazine showed that in Spain the full boost happened in some part of the track in 2016 where there was none in 2017, and the difference is not exactly tiny. This could indicate recovering energy also happens during overrun (mid-corner no braking), or partial throttle at corner exit.

It took some of the power unit makers up to 2017 - 18 to believe that they have reached the top - which was back then producing an MGU-K that can deliver 120kw, it's fully permitted potential. Those two that believed so have than turned their attention to catch-up in how they can gain some 'EXTRA' harvesting even if it could potentially be considered not within the spirits of the harvesting energy rules, This line of thinking was as a consequence of lack of policing by the rule makers, which in turn was due to technical problems to do so. This can be confirmed by the late Charlie W saying that there was no way they could properly understand what FERRARI were doing until they produced and made use of very sophisticated software. Since then and since they introduced mandatory upgraded MGU-K IN - OUT sensors, this was right after the Japanese magazine outed the Honda 'EXTRA' HARVESTING which many on here promptly declared as being legal.

[saviour stivala]

It, the turbocharger turbine used in F1 being a pressure type of turbine + the waste-gate/s used are designed to bypass exhaust gases from the turbine, when waste-gate/s are open the turbine is simply riding along on the turbo shaft while the whole thing is motored by the 'H', which in turn is sharing 'ES' power with 'K'. (electric supercharging mode/free load mode).

the above is incorrect ......
unless the exhaust gas is entirely diverted away from the turbine and the main exhaust pipe

but .....
the turbine actually gets 1 atm exhaust so kinetic pulses/waves still (quite weakly) power the turbine and compressor
this power recovery-without-backpressure is the so-called blowdown recovery
here it somewhat reduces the amount of ES energy needed by the MGU-H in driving the compressor
so increasing the available duration of this ('electric supercharge') running mode

there is no evidence that the turbine responds only to mean exhaust pressure (is unresponsive to kinetic 'pulses')
clearly all 4 makes of ICE have exhaust manifolds designed to encourage these pulses
and the pulses are anyway relatively stronger in 1 atm exhaust than in the main ('backpressure') running mode

It is your accredits which are wrong. First. Any exhaust gas past the exhaust valve is 'blow-down' gas. Secondly. The turbine used in F1 is not a blow-down turbine like used by the Wright Cyclone, but a pressure turbine. A blow-down turbine will not have a waste-gate because it doesn't need pressure to produce useful work. The F1 turbine needs exhaust gas pressure to produce useful work, when waste-gate/s are opened the exhaust gas pressure is dropped to atmospheric pressure, and any gases inside the turbine at atmospheric pressure cannot make the turbine do any useful work because turbine can only do so under exhaust gas pressure.

[gruntguru]

It, the turbocharger turbine used in F1 being a pressure type of turbine + the waste-gate/s used are designed to bypass exhaust gases from the turbine, when waste-gate/s are open the turbine is simply riding along on the turbo shaft while the whole thing is motored by the 'H', which in turn is sharing 'ES' power with 'K'. (electric supercharging mode/free load mode).

the above is incorrect ......
unless the exhaust gas is entirely diverted away from the turbine and the main exhaust pipe

but .....
the turbine actually gets 1 atm exhaust so kinetic pulses/waves still (quite weakly) power the turbine and compressor
this power recovery-without-backpressure is the so-called blowdown recovery
here it somewhat reduces the amount of ES energy needed by the MGU-H in driving the compressor
so increasing the available duration of this ('electric supercharge') running mode

there is no evidence that the turbine responds only to mean exhaust pressure (is unresponsive to kinetic 'pulses')
clearly all 4 makes of ICE have exhaust manifolds designed to encourage these pulses
and the pulses are anyway relatively stronger in 1 atm exhaust than in the main ('backpressure') running mode

It is your accredits which are wrong. First. Any exhaust gas past the exhaust valve is 'blow-down' gas. Secondly. The turbine used in F1 is not a blow-down turbine like used by the Wright Cyclone, but a pressure turbine. A blow-down turbine will not have a waste-gate because it doesn't need pressure to produce useful work. The F1 turbine needs exhaust gas pressure to produce useful work, when waste-gate/s are opened the exhaust gas pressure is dropped to atmospheric pressure, and any gases inside the turbine at atmospheric pressure cannot make the turbine do any useful work because turbine can only do so under exhaust gas pressure.

With wastegate open, the pressure in the exhaust does not drop to atmospheric. Have you ever heard of wave tuning? The exhaust collector sees pulses of up to 2.5 atmospheres on a NA engine - higher on a supercharged engine. Are these pulses able to force their way into the rapidly spinning turbine and generate any power with the wastegate open? Who knows. Certainly there will be some partially-open settings for the wastegate where useful turbine power is generated while reducing average exhaust pressure sufficiently to increase crankshaft power.

[saviour stivala]

The formula one turbo-supercharger utilizes a pressure turbine with an external waste-gate and not a build-into-turbine-housing waste-gate. As such the formula one waste-gate does not control turbo boost, and when open exhaust gas collector pressure is at atmospheric pressure.
In this type of installation cylinders exhausts into a common collector with two possible exits paths. One through a variable open waste-gate, and the other through a nozzle aimed at a turbine wheel. With waste-gate opened there is no restriction, and collector pressure is at atmospheric pressure. As waste-gate is closed, pressure builds-up in collector No power recovery is possible in such a system unless the collector is above exiting at atmospheric pressure.

[Tommy Cookers]

.. No power recovery is possible in such a system unless the collector is above exiting at atmospheric pressure.

that is 100 year-old (wrong) thinking
the NACA proved this wrong 80 years ago
15000 Wright engines proved this wrong 70 years ago

F1 doesn't have 'collectors'
it has (just like Wright and modern road cars) systems that transmit exhaust pulses to the turbine
free power


and this apparently interminable argument doesn't belong in this 2026 F1 thread

[wuzak]

The formula one turbo-supercharger utilizes a pressure turbine with an external waste-gate and not a build-into-turbine-housing waste-gate. As such the formula one waste-gate does not control turbo boost, and when open exhaust gas collector pressure is at atmospheric pressure.

Many/most aftermarket turbos do not have an internal wastegate, so an external wastegate has to be used. The wastegate, or gates, is usually fitted somewhere on the exhaust. The gates are used to control the flow to the turbo.

Sometimes the wastegates can be positioned poorly, and they don;t give very good control.

The wastegate(s) in an F1 could be used to control the boost if, for some reason, the MGUH was not able to perform the task.

[wuzak]

5.10.1 With the exception of incidental leakage through joints (either into or out of the system) and power unit breather fluids, all and only the fluids entering the compressor inlet and fuel injectors must exit from the engine exhaust system.

Does this allow the use of a blow-off valve to send air from the compressor directly into the exhaust to help keep he turbo spinning?