2025/2026 Hybrid Powerunit speculation

[saviour stivala]

Maximum power to the wheels possible is when the ICE is run in 'free load mode' in this mode the ICE is at full fueling and is in supercharging mode, with waste gate/s opened and MGU-K and H are sharing battery power.

[gruntguru]

Nobody mentioned maximum power to the wheels. Thermal efficiency is calculated by dividing power out by power in (fuel flow) with no change in stored energy within the system.

[gruntguru]

Wasn't the reported 50% efficiency of the current engines achieved when the compressor side was run as a supercharger with MGU-H and the turbine side running with the wastegates open?

I've always thought the above 50% figures were the ICE + MGU-H recovery.

Sorry, I have no knowledge of that claim or its validity.

[mzso]

I would think that the peak efficiency was achieved with the MGUH and MGUK working in a turbo-compound mode.

That is, the recovered energy from the MGUH directly drives the MGUK and no energy is transferred to or from the battery.

When the MGUH is driving the turbo it is taking energy from the battery. Therefore using more energy than can be extracted from the fuel.

That is a good mode, but that is not the maximum power to the wheels.

Assuming 1000hp in total in qualifying
160 hp comes from MGUK
840 hp comes from ICE with battery powering the MGUH to drive the compressor and turbines running with waste gates open
840 hp is 620 kw which is 50% of available energy from 100 kg of fuel

Okay, but the discussion was about efficiency.

[wuzak]

I would think that the peak efficiency was achieved with the MGUH and MGUK working in a turbo-compound mode.

That is, the recovered energy from the MGUH directly drives the MGUK and no energy is transferred to or from the battery.

When the MGUH is driving the turbo it is taking energy from the battery. Therefore using more energy than can be extracted from the fuel.

That is a good mode, but that is not the maximum power to the wheels.

Assuming 1000hp in total in qualifying
160 hp comes from MGUK
840 hp comes from ICE with battery powering the MGUH to drive the compressor and turbines running with waste gates open
840 hp is 620 kw which is 50% of available energy from 100 kg of fuel

Fuel power is 1,250kW at 100kg/h, assuming 45MJ/kg fuel.

840hp is 626kW. Which gives 50.1% thermal efficiency.

If we say the ICE gives 600kW (804hp) and that the MGUH can recover 40kW and send it to the MGUK then the total ICE output is 640kW, which is an efficiency of 51.2%.

If the MGUH recovers 60kW, the efficiency jumps to 52.8%.

The total power of the PU is less because the MGUK output is limited. In both turbo compounding modes the total power available is the ICE power (600kW) plus the maximum MGUK output (120kW), which is 720kW.

1,000hp is ~750kW.

[saviour stivala]

Running with wastegates closed is considered to be the most efficient solution for normal racing conditions. however, in qualifying conditions and during a race were defending and or overtaking are encountered, running the engine with wastegate open the power of the ICE is vastly boosted.

[wuzak]

Without the MGUH spooling the turbo in maximum power mode, it would appear that the 2026 PUs should have the same performance in the race as they do qualifying.

[saviour stivala]

Without the MGUH spooling the turbo in maximum power mode, it would appear that the 2026 PUs should have the same performance in the race as they do qualifying.

Obvious when the rules have eliminated the 'ICE free-load-mode'.

[wuzak]

Without the MGUH spooling the turbo in maximum power mode, it would appear that the 2026 PUs should have the same performance in the race as they do qualifying.

Obvious when the rules have eliminated the 'ICE free-load-mode'.

They will be able to use more energy on qualifying laps as they don't have to balance usage with recovery.

[saviour stivala]

Without the MGUH spooling the turbo in maximum power mode, it would appear that the 2026 PUs should have the same performance in the race as they do qualifying.

Obvious when the rules have eliminated the 'ICE free-load-mode'.

They will be able to use more energy on qualifying laps as they don't have to balance usage with recovery.

Battery power, yes they will, the same as they do now, in qualifying mode over a lap battery power and fuel burn is no problem.

[wuzak]

Under the latest version of the regulations posted by the FIA there will be 8 forward gears.

I had expected them to reduce the number of gears, perhaps to 6.

Fewer gears would save some weight, but would also means that the engines would have to run to higher rpm in order to stay in the peak power range.

[Tommy Cookers]

Under the latest version of the regulations posted by the FIA there will be 8 forward gears.
I had expected them to reduce the number of gears, perhaps to 6.
Fewer gears would save some weight, but would also means that the engines would have to run to higher rpm in order to stay in the peak power range.

8 speeds is even more helpful to the electric side than 6 speeds would be