2025/2026 Hybrid Powerunit speculation

[mzso]

So, by the sound of it (Pat Symonds talking) it's because of the manufacturer's insistence (Which means PR/marketing reasons) that they went for the "drop-in" ideology.
Which is rather misguided, and meaningless. For ages it is possible to modify a car to run on LPG, which is propane and butane.
Coincidentally these materials are easy to produce, even biologically directly from bio-waste, actually have better energy density than petrol. Also they can be used in fuel cells, if things go in that direction.
So cheaper, more practical and more efficient.

Gas?

Gas what? Symonds was talking about how they went for drop in bio-fuel because that is what engine manufacturers suggested.

No, I believe it was more like Fischer-Troppz fuel or mixed with butanol. A real 1:1 drop-in for gasoline refined from mineral oil.

Again, I'm not sure what you're responding to. You mean the FIA bio-fuel they created? Did they even release details about their fuel/process?

[mzso]

This is an embarrassingly bad take. They had a one cylinder prototype on the bench in summer 2022. A man in a garage can build a one cylinder prototype.

In Milton Keynes on the evening of 3 August, a full engine of [Red Bull's] own manufacture was fired up for the first time.
[...]
RacingNews365.com has learned that the engine, which has not yet been given an official type name, was a full six cylinder unit rather than a single cylinder test engine: a major milestone for the team given the short time frame.

Renault also had an engine in 2014, and Honda had one in 2015. Wasn't worth much was it? How many years did it take them to make a PU that could actually do 6-7 GPs? Renault took 5 years. Honda took 4 years. This all while actually having PUs racing around on the track.

The difference between a block of steel that fires up on a dyno, and PU that wins a championship is quite large.

You're missing the point, 2014 and 2015 are too late. Mercedes probably had one working in 2011.
And if it's true that RB already has a functioning engine, it means that they are in a good state, seeing as they still have three more years.

Unlike some, I'm not actually all that optimistic about the RBPT PU. This is the kind of thing that could send them a big step backwards in competitiveness.

I see no reason for pessimism so far. They brought in people with relevant knowledge from both Honda and Mercedes. Plus they clearly have very good practices and engineering processes, because they're are successful at everything they already design and manufacture.

[wuzak]

Again, I'm not sure what you're responding to. You mean the FIA bio-fuel they created? Did they even release details about their fuel/process?

The FIA have created a fuel specification, not a fuel.

The fuel partners will be doing the development.

The fuel will have quite a bit less energy density than what they currently have.


The disappointment I had with the interview of Pat Symonds was that they didn't ask how these power units will work, or why they made the PU the same mass as the current PU or what racing would look like in 2026.

[mzso]

Again, I'm not sure what you're responding to. You mean the FIA bio-fuel they created? Did they even release details about their fuel/process?

The FIA have created a fuel specification, not a fuel.

The fuel partners will be doing the development.

The fuel will have quite a bit less energy density than what they currently have.


The disappointment I had with the interview of Pat Symonds was that they didn't ask how these power units will work, or why they made the PU the same mass as the current PU or what racing would look like in 2026.

I quite clearly recall an announcement that the FIA created a process to produce bio fuel from otherwise unused waste.
Quite a bit more than specifying, as they did before.

[johnny comelately]

Again, I'm not sure what you're responding to. You mean the FIA bio-fuel they created? Did they even release details about their fuel/process?

The FIA have created a fuel specification, not a fuel.

The fuel partners will be doing the development.

The fuel will have quite a bit less energy density than what they currently have.


The disappointment I had with the interview of Pat Symonds was that they didn't ask how these power units will work, or why they made the PU the same mass as the current PU or what racing would look like in 2026.

I have questions regarding energy density, it would make the most sense to have the highest as this would be the least weight which is a penalty either on the track or road. Therefore the flow rate would be less (depending on the stoichmetry of the new fuel, which could be anything!) but of course this relates to engine capacity which would be smaller.

[wuzak]

Again, I'm not sure what you're responding to. You mean the FIA bio-fuel they created? Did they even release details about their fuel/process?

The FIA have created a fuel specification, not a fuel.

The fuel partners will be doing the development.

The fuel will have quite a bit less energy density than what they currently have.


The disappointment I had with the interview of Pat Symonds was that they didn't ask how these power units will work, or why they made the PU the same mass as the current PU or what racing would look like in 2026.

I have questions regarding energy density, it would make the most sense to have the highest as this would be the least weight which is a penalty either on the track or road. Therefore the flow rate would be less (depending on the stoichmetry of the new fuel, which could be anything!) but of course this relates to engine capacity which would be smaller.

Engine capacity does not change.

But, yes, higher density would be preferred.

The allowed range is 38MJ/kg to 41MJ/kg.

That equates to 78.9kg/hr fuel flow rate for energy density of 38MJ/kg and 73.2kg/hr for 41MJ/kg.

Or around 7.3% less mass for a given amount of energy.

[johnny comelately]

The FIA have created a fuel specification, not a fuel.

The fuel partners will be doing the development.

The fuel will have quite a bit less energy density than what they currently have.


The disappointment I had with the interview of Pat Symonds was that they didn't ask how these power units will work, or why they made the PU the same mass as the current PU or what racing would look like in 2026.

I have questions regarding energy density, it would make the most sense to have the highest as this would be the least weight which is a penalty either on the track or road. Therefore the flow rate would be less (depending on the stoichmetry of the new fuel, which could be anything!) but of course this relates to engine capacity which would be smaller.

Engine capacity does not change.

But, yes, higher density would be preferred.

The allowed range is 38MJ/kg to 41MJ/kg.

That equates to 78.9kg/hr fuel flow rate for energy density of 38MJ/kg and 73.2kg/hr for 41MJ/kg.

Or around 7.3% less mass for a given amount of energy.

So you are going from 100kg/hr to say 79kg/hr staying at 1600cc?
Currently at 1.25 lambda
which means going 1.6 lambda (roughly) maintaing the 1600cc, is the boost coming down by 25% ?
how is this possible?

[wuzak]

I have questions regarding energy density, it would make the most sense to have the highest as this would be the least weight which is a penalty either on the track or road. Therefore the flow rate would be less (depending on the stoichmetry of the new fuel, which could be anything!) but of course this relates to engine capacity which would be smaller.

Engine capacity does not change.

But, yes, higher density would be preferred.

The allowed range is 38MJ/kg to 41MJ/kg.

That equates to 78.9kg/hr fuel flow rate for energy density of 38MJ/kg and 73.2kg/hr for 41MJ/kg.

Or around 7.3% less mass for a given amount of energy.

So you are going from 100kg/hr to say 79kg/hr staying at 1600cc?
Currently at 1.25 lambda
which means going 1.6 lambda (roughly) maintaing the 1600cc, is the boost coming down by 25% ?
how is this possible?

Yes, 1.6L 90° V6, maximum fuel/energy flow rate is achieved at 10,500rpm, after which it remains constant to the rpm limit of 15,000. And the same minimum mass as the current regulations.

Maximum compression ratio has gone from 18:1 to 16:1.

From the 2026 regulations:
5.5.2 Engine inlet air pressure must be less than 4.8 barA at all times. The pressure of the air will be measured by an FIA approved and sealed sensor located in an FIA approved location situated in the engine inlet system.

From what I can see at the moment, there is no limit to boost/MAP in the current regulations.

[wuzak]

So you are going from 100kg/hr to say 79kg/hr staying at 1600cc?

Yes, they are reducing energy flow by approximately 1/3.

Approximately because we don't know the specifications of current fuel.

The aim is to reduce ICE power from approximately 600kW to approximately 400kW.

[johnny comelately]

Engine capacity does not change.

But, yes, higher density would be preferred.

The allowed range is 38MJ/kg to 41MJ/kg.

That equates to 78.9kg/hr fuel flow rate for energy density of 38MJ/kg and 73.2kg/hr for 41MJ/kg.

Or around 7.3% less mass for a given amount of energy.

So you are going from 100kg/hr to say 79kg/hr staying at 1600cc?
Currently at 1.25 lambda
which means going 1.6 lambda (roughly) maintaing the 1600cc, is the boost coming down by 25% ?
how is this possible?

Yes, 1.6L 90° V6, maximum fuel/energy flow rate is achieved at 10,500rpm, after which it remains constant to the rpm limit of 15,000. And the same minimum mass as the current regulations.

Maximum compression ratio has gone from 18:1 to 16:1.

From the 2026 regulations:
5.5.2 Engine inlet air pressure must be less than 4.8 barA at all times. The pressure of the air will be measured by an FIA approved and sealed sensor located in an FIA approved location situated in the engine inlet system.

From what I can see at the moment, there is no limit to boost/MAP in the current regulations.

With respect I cant see how that explains it, unless the current boost is 5.5 to 6 bar which i dont think it is.
So how are we going to run at circa 1.65 lambda

[wuzak]

With respect I cant see how that explains it, unless the current boost is 5.5 to 6 bar which i dont think it is.
So how are we going to run at circa 1.65 lambda

I can't explain how it works.

The 4.8bar MAP is the maximum, so they can use less. They don't have to go to the maximum.

But in general, I don't think the rules make sense.

They could have gone with a 1.0 - 1.1L engine of 3, 4 or even, 6 cylinders to use similar parameters as know and get the target power.

A 3 or 4 cylinder engine would have allowed some weight saving as well.


I suspect that new manufacturers wanted the combustion to be different to current units so that they would have a chance of matching the current suppliers.

[mzso]

So you are going from 100kg/hr to say 79kg/hr staying at 1600cc?

Yes, they are reducing energy flow by approximately 1/3.

Approximately because we don't know the specifications of current fuel.

The aim is to reduce ICE power from approximately 600kW to approximately 400kW.

Do the regulations say whether regen is possible when the brake pedal is not pressed? Which is not possible with today's rules, AFAIK.

[saviour stivala]

So you are going from 100kg/hr to say 79kg/hr staying at 1600cc?

Yes, they are reducing energy flow by approximately 1/3.

Approximately because we don't know the specifications of current fuel.

The aim is to reduce ICE power from approximately 600kW to approximately 400kW.

Do the regulations say whether regen is possible when the brake pedal is not pressed? Which is not possible with today's rules, AFAIK.

A RBPT engineer working on the new for 2026 power unit project talking to RET said that it will still not be permitted. This was already discussed on another page on here.

[gruntguru]

I am sure regen is currently possible without pressing the brake pedal. (eg lift and coast) What is not certain is whether regen is allowed while the ICE is under load.

[henry]

Currently :

At part throttle they can mix power from the ICE and MGU-K so long as the resultant power output matches the driver’s demand. Originally the only restriction was the part throttle fuel flow requirement, more recently they also provide a fuel flow to power demand requirement. So if demand is 400kW you can make it with 450kW ICE and regen 50kW with the K.

At full throttle the contribution of the K to the power output is wholly under software control. So at the beginning of the straight it can be 600kW ICE and +120kW from the K and at the end 600 ICE and -120 K.

There was NEVER EVER a requirement to link the K regen to the brake pedal. They CAN, and do, use the K for braking but there is no regulation that says they MUST.

What they will do in 2026 I don’t know. They seem to have dropped the fuel flow to power restriction on part throttle so maybe they expect part throttle regen to try to make up for the shortfall, versus the current state, caused by removing the MGU-H.