2025/2026 Hybrid Powerunit speculation

[DoctorRadio]

The engineering calculus behind Ferrari's Steel choice:

The news of Ferrari experimenting with a steel alloy cylinder head is a masterclass in sophisticated engineering. Far from a step backward, this move can be seen as a precise, strategic calculation where the advantages are decisive and the apparent drawbacks are not obstacles, but simply new parameters for innovation.

The Decisive Advantages:

· Unmatched Durability & Power Density: Steel's inherent strength offers an unprecedented foundation for engine rigidity and longevity. Crucially, this strength allows for a more compact and power-dense design, a critical advantage for packaging and vehicle
dynamics.

· Enhanced Thermal Efficiency: By retaining more combustion heat within the cylinder, steel directly boosts thermodynamic efficiency. This translates to a tangible gain in power and torque, extracting more work from every drop of fuel.

· Strategic Manufacturing Efficiency: The use of steel can streamline production, offering cost and complexity benefits that can be redirected into other areas of advanced engineering.

The Challenges, Recontextualized:
The characteristics often framed as weaknesses are, in this light, not prohibitive, but simply key elements of the design equation—elements Ferrari's engineers are uniquely equipped to solve.

· Weight: While steel is denser, the ability to create a significantly smaller and more compact engine package can lead to a net neutral—or even favorable—impact on overall vehicle weight distribution. The mass is centralized and used structurally.

· Thermal Management: Modern Ferrari engines are masterpieces of thermal management, with advanced, track-proven cooling systems. The "challenge" of heat retention becomes the "opportunity" for precise temperature control, turning a potential drawback into a tunable performance variable.

· Modern Relevance: To label this choice "outdated" is to misunderstand Ferrari's history of rewriting conventions. If any manufacturer can leverage the core benefits of steel while mitigating its traditional downsides through material science and systems engineering, it is Ferrari. This isn't a return to the past; it's a reapplication of a fundamental material with a modern toolkit.

Conclusion:
The narrative isn't about accepting old compromises. It's about Ferrari seeing a clear path where the profound benefits of strength, efficiency, and packaging are paramount, and where their engineering prowess renders the typical disadvantages manageable—or even advantageous. This is not a compromise; it's a calculated pursuit of a specific performance ideal.

From https://x.com/Scuderiascoop/status/2007937763920785860

so that people can confirm or debunk what is written there.

[Vappy]

For a lot of points and words, not a lot of technical value has been brought to the discussion by the person who posted that tweet. It sounds very much like good ol' AI generalisation, in fact.

[fourmula1]

How does the electrical energy and deployment work with these - is it difficult to have enough energy on hand to use 100% of the power when wanted over the course of the entire race? Is recharging/recovery a potential gateway to more performance? Or do they start fully charged and with some recovery they are able to have enough energy on hand for max power when needed?

[johnnycesup]

Steel is an alloy that uses iron as an ingredient. That doesn’t make it iron. Especially when ‘cast iron’ these days contains a lot of other elements which means they are technically alloys not cast iron. Which in my book makes the 2% carbon the key point, less than that and it is a steel alloy that is not allowed. Above that it is an iron alloy and it is allowed. Though why anyone would want a CI head in F1 is a mystery.

In the current version of the regulations:

https://www.fia.com/system/files/docume ... 2-10_0.pdf

The relevant section is as follows:

C15.7.8 Static components:
a. Other than Inserts within them, engine crankcases including sump, Cylinder Heads, their
respective covers and cylinder head cam covers must be manufactured from aluminium or
iron-based alloys.

In Part C of the regulations we can find the definition of what a "X Based Alloy" is:

“X Based Alloy”: (e.g., Ni based alloy) – X must be the most abundant element in the alloy on a
%w/w basis. The minimum possible weight percent of the element X must always be greater than
the maximum possible of each of the other individual elements present in the alloy.

So yes, steel is an Iron-based alloy as far as the regulations are concerned. There are even specific steel grades, like AMS 6487 (a low alloy steel with 0.4%Carbon), in the list for allowable iron-based alloys for pistons.

[Badger]

Extra weight in the cylinder head… I’m no engineer but wouldn’t the moving engine parts be the last place you want heavier components? Doesn’t that just zap power?

[Hoffman900]

Extra weight in the cylinder head… I’m no engineer but wouldn’t the moving engine parts be the last place you want heavier components? Doesn’t that just zap power?

From a weight standpoint yes, but there is an argument that an iron head may have a more stable deck / combustion chamber. F1 engines run very high peak cylinder pressures (about we much as a drag racing Pro Modified), and there may be advantages here.

With modern casting , printing, machining technologies, there may be an opportunity to make a much more slimmed down iron head than a subsequently bulkier aluminum head to equal the same stability deck and chamber).

[mzso]

Yes, steel is very much an iron alloy.

I suspect they used the term iron alloy rather than steel so they don't have to define what steel is.

It's pretty vague though. Loosely you can call any alloy an iron alloy as long it has iron in it. You can most definitely call it an iron alloy if it has 50%+ iron.

I don’t believe it does. You can have an iron alloy, in fact what most people know as ‘cast iron’ these days is an alloy as they contain more than iron and carbon.

Also steel. Just because you call it steel it doesn't stop being an iron alloy. Steel is just a more specific term.

[diffuser]

How does the electrical energy and deployment work with these - is it difficult to have enough energy on hand to use 100% of the power when wanted over the course of the entire race? Is recharging/recovery a potential gateway to more performance? Or do they start fully charged and with some recovery they are able to have enough energy on hand for max power when needed?

I'd go back and read a good post from Wuzak https://www.f1technical.net/forum/viewt ... k#p1306185 and all the stuff in and around that to answer your question.

[mzso]

Extra weight in the cylinder head… I’m no engineer but wouldn’t the moving engine parts be the last place you want heavier components? Doesn’t that just zap power?

The cylinder head isn't a moving part.

[wuzak]

Thank you, so ultimately it's not 'measuring' (I am still wondering whether it's even possible) but actually 'determining', and that too specific to the ICE alone. Ok.
Pardon my ignorance, but what constitutes Z=0 ? the bottom of the survival cell or the bottom of the floor ? When the floor is 'raked' what will happen to the Z=0 point ? In case the Z=0 is the tarmac (which I don't think it would be) what happens when different tyre pressures or different ride heights are used ?

Z = 0 is the reference plane, from which all heights are measured.

On the 2025, and previous, regulations with a "stepped" floor, the reference plane is the bottom of the central section of the floor.

The plank is mounted on the reference plane, with all of it below the reference plane.

If the car is raked, so is the reference plane.

The rake is a suspension setting, and does not have an influence on measurements from the reference plane.

[wuzak]

Steel is an alloy that uses iron as an ingredient. That doesn’t make it iron. Especially when ‘cast iron’ these days contains a lot of other elements which means they are technically alloys not cast iron. Which in my book makes the 2% carbon the key point, less than that and it is a steel alloy that is not allowed. Above that it is an iron alloy and it is allowed. Though why anyone would want a CI head in F1 is a mystery.

Steel is an iron alloy.

Alloy in the term "Steel alloy" is superfluous. Steel is an alloy.

[wuzak]

There seems to be a few surprise freedoms within the turbocharger regs:

https://i.postimg.cc/3N591Byg/turbo-regs.png

F.e. the turbine isn’t demanded to be single-sided, only the compressor is. A dual outlet turbine could provide some new options for wheel ramp profiles and oulet area (think of a double-sided compressor wheel). Also, directionality of flow is not specified, so a radial-outlfow turbine could be pursued. Is the inlet:outet area ratio of a turbocharger turbine considered to be a limiting factor in terms of geometry and packaging?

Keeping in mind the overall depth and diameter specs, and the rotational velocity limit, consider: inlet and outlet area can both be relatively greater, or I could provide up to twice the amount of outlet area relative to the inlet area, compared to a conventional design.

C5.3.1 Pressure charging may only be affected by the use of a sole single stage, single sided Turbo Charger compressor with a single inlet linked to a sole single stage Turbo Charger turbine by a shaft assembly. The compressor blades must be attached to a common hub surface and all air entering the Combustion Chamber must pass through the single exducer of these blades. The shaft must be designed so as to ensure that the shaft assembly, the compressor and the turbine always rotate about a common axis and at the same angular velocity. Moreover, all rotating parts of the Turbo Charger must have a fixed inertia by design.

C5.3.3 The axis of the turbocharger shaft must be parallel to Y=0, inboard of Y=25 and at an angle of 0 +/- 1 degree to X=axis.

C5.8.2 All turbine exit and all Wastegate exhaust fluids must pass through the Exhaust Tailpipe defined in Article C3.9.2.

These make your idea extremely difficult (impossible?).

A radial outflow turbine would require the exhaust to enter at the centre.

For a single sided outflow turbine, the exhaust would have to go behind the turbo, turn 180°, and then go forward to the turbine inlet.

For a double sided outflow turbine, one exhaust would do as above, and the other would have to enter the turbine in the space between the turbine and compressor. Where the shaft is, and where space is extremely limited.

If the rules allowed the turbine rotational axis to be different to the compressor rotational axis (eg 90°), it may be possible.

[wuzak]

IIRC, the last of the Ferrari F1 V12s used a cast steel block.

[venkyhere]

There is so much chatter about 'steel cylinder head' in the media (as well as here) and it has left me wondering :
The engine is the same 1.6L as the previous era yet is now going to produce 500bhp peak, instead of 800bhp peak before, so lower max boost level, lower peak pressures etc etc. So why has 'ICE performance' suddenly become a hot topic ? Or has the fuel flow rate limit been massively reduced, demanding more 'efficiency' ? What am I missing ?

[wuzak]

There is so much chatter about 'steel cylinder head' in the media (as well as here) and it has left me wondering :
The engine is the same 1.6L as the previous era yet is now going to produce 500bhp peak, instead of 800bhp peak before, so lower max boost level, lower peak pressures etc etc. So why has 'ICE performance' suddenly become a hot topic ? Or has the fuel flow rate limit been massively reduced, demanding more 'efficiency' ? What am I missing ?

It's because the hybrid rules require every last hp.

In the previous rules, a few hp didn't really change much.

But under the 2026 rules, extra power means more opportunity to recover energy to the battery.