Honda Power Unit Hardware & Software

[mzso]

Moving this thread from the AMR team thread.

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Turbo size can't be changed with aduo. Nobody is entirely sure what they did, but the most common rumours were changing vane shape and the number of them.

This is actually an important call out, regarding keeping the turbo size the same but changing the internals.

I don't think it's true. As I recall from when I looked at the table, pretty much everything could be changed with ADUO.

[mzso]

I don't want to re litigate this but for accuracy I'm 100% sure Renault did adopt the split turbo. Ferrari, may not have.

If I don’t remember it wrong renault and Ferrari put turbo and turbine next to each other and then Ferrari switched split turbo

As I recall Ferrari never used a split turbo.

[diffuser]

Holy AI slop

F1 has a max boost pressure and a max turbo shaft RPM, so smaller turbos may struggle to reach max boost at higher altitude due to the RPM limit and reliability. A larger turbo will not need to spin as fast to reach the same boost. The trade-off under normal circumstances would be more lag on the larger turbo, however, the era we are talking about (2014-2025) had the MGU-H which spun up the turbo independent of exhaust flow to eliminate all turbo lag. This made larger turbos significantly better at altitude. Honda likely ran bigger turbos during the years where they were more competitive at high altitude (2019 for example).

It's the other way around. Smaller turbo will find it easier to reach max boost. They are lighter and spin more freely, therefore, deal better with loss of exhaust gas cause by thinner air at altitude.

A smaller turbo will need to spin extremely fast to reach the max allowed boost at higher altitude, this creates reliability issues (and there's a max turbo rpm too, 100k IIRC). Also, we've already established it's the MGU-H that span up the turbo on those cars, so the loss of exhaust gas doesn't matter because the turbo was always spooled. There's a reason RB was able to win in Mexico 2017 and 2018 with the infamous Renault engine (which had a larger turbo than the competition).

AI isn't covering up the gaps in your knowledge mate, it's exposing them.

https://www.formula1.com/en/latest/arti ... hatgpt.com

Renault’s turbochargers remain smaller than those used by Mercedes and Ferrari and it’s quite feasible that their burst point is correspondingly higher. If their smaller turbos are capable of running faster before their burst point, it would allow the turbo to compensate more for the lower oxygen content, thereby overcoming its power shortfall at lower altitudes.

[ispano6]

Moving this thread from the AMR team thread.

...

Turbo size can't be changed with aduo. Nobody is entirely sure what they did, but the most common rumours were changing vane shape and the number of them.

This is actually an important call out, regarding keeping the turbo size the same but changing the internals.

I don't think it's true. As I recall from when I looked at the table, pretty much everything could be changed with ADUO.

I agree, I don't think the size is restricted by ADUO if granted. I do also believe changing the size of the turbo within a season is costly. Depending on it's packaging, it could require much more architectural changes to achieve, thus the only sensible route is to change the internal shape and A/R ratio, blade shape, count, possibly keeping the external dimensions the same but increasing the volume, perhaps with thinner walls of the turbine housing? That has consequences too.

Like Badger mentioned correctly Honda made use of the MGUH to assist the turbo, and that is gone now. So a small turbo concept could have been a mistake for this season. Alonso did get off the line and make up 10 positions in the opening laps of some early races, but dropped back after the other cars harvested more. So maybe what Asaki is saying is reflective or Honda's approach they needed to reconsider.

[diffuser]

Moving this thread from the AMR team thread.



This is actually an important call out, regarding keeping the turbo size the same but changing the internals.

I don't think it's true. As I recall from when I looked at the table, pretty much everything could be changed with ADUO.

I agree, I don't think the size is restricted of ADUO. I do also believe changing the size of the turbo within a season is costly. Depending on it's packaging, it could require much more architectural changes to achieve, thus the only sensible route is to change the internal shape and A/R ratio, possibly keeping the external dimensions the same but increasing the volume, perhaps with thinner walls of the turbine housing? That has consequences too.

Like Badger mentioned correctly Honda made use of the MGUH to assist the turbo, and that is gone now. So a small turbo concept could have been a mistake for this season. Alonso did get off the line and make up 10 positions in the opening laps of some early races, but dropped back after the other cars harvested more. So maybe what Asaki is saying is reflective or Honda's approach they needs to reconsider.

There is a turbo max size in the regs that need to be respected. So you can increase the size with ADUO but not beyond the max size.

[etusch]

As I recall Ferrari never used a split turbo.

I've made a search and yes not renault only ferrari sticked their first concept. Renault shift split turbo at 2022 pu.

[mzso]

There is a turbo max size in the regs that need to be respected. So you can increase the size with ADUO but not beyond the max size.

That's obvious, regs are regs. I don't think anyone claimed that.

[diffuser]

There is a turbo max size in the regs that need to be respected. So you can increase the size with ADUO but not beyond the max size.

That's obvious, regs are regs. I don't think anyone claimed that.

I wanted it out there, not everyone is as informed as you. LOL, those NOT informed probably won't read my post but I tried!

[ispano6]

A high level summary by Gemini based on all of the sources I had it consume. Yes, it's an informed AI summary so if you're a skeptic feel free to ignore.

Honda’s power unit struggles stem from a cascading interaction between Aramco's synthetic fuel chemistry, 2026 engine regulations, and mechanical chassis integration.
1. Synthetic Fuel Chemistry & Pre-Chamber Sensitivity
Supplier Transition & Fuel Synergy: Switching to Aramco's 100% sustainable synthetic formulation (Aramco ProForce+) forced Honda to rebuild years of empirical dyno calibration previously optimized around ExxonMobil chemistry.
Flame Speed & Atomization: Synthetic hydrocarbons exhibit lower laminar burning velocities and distinct evaporation profiles, directly altering flame front propagation inside the cylinder.
Turbulent Jet Ignition (TJI) Limits: F1 pre-chambers rely on precise micro-atomization. Unpredictable synthetic fuel vaporization causes the pre-chamber flame jets to fire unevenly into the main cylinder, preventing a rapid, uniform burn front.
Knock & Auto-Ignition Margins: Lower knock resistance under 2026 compression ratios forces engineers to retard ignition timing and enrich air-fuel mixtures, cutting thermal efficiency and top-end horsepower.
2. Removal of the MGU-H & Pressure Dynamics
Loss of Turbo Speed Control: The elimination of the MGU-H under 2026 rules removes active electrical speed control over the turbocharger shaft, leaving intake manifold pressure unbuffered.
Transient Pressure Spikes: Sudden throttle transitions create air density fluctuations in the intake plenum, disrupting the pre-chamber's fragile fuel-air balance.
Energy Flow Restrictions: Under the 3,000 MJ/h total energy displacement limit, combustion inefficiencies can no longer be offset by increasing fuel mass flow, heavily penalizing energy density mismatches.
3. Harmonics, Cyclic Dispersion & Vibrations
Uneven Cylinder Pressure: Stroke-to-stroke burn rate variances (cyclic dispersion) across cylinders produce erratic peak pressure spikes.
Torsional Vibration: As reported by The Race, these inconsistent combustion pulses induce severe high-frequency harmonic vibrations along the crankshaft.
Reliability Feedback Loop: Mechanical vibrations transfer into the chassis, damaging onboard electronics, sensors, and battery components. To avoid structural failures, Honda is forced to run detuned, conservative engine maps.
4. Packaging Constraints & Thermal Management
Chassis Integration: Tight packaging around the Aston Martin AMR26 sidepods and engine cover restricts cooling airflow across the power unit cylinder heads.
Heat Accumulation: Reduced thermal margins increase heat retention within the combustion chamber, compounding knocking risks and locking the engine into an unstable combustion loop.

[diffuser]

A high level summary by Gemini based on all of the sources I had it consume. Yes, it's an informed AI summary so if you're a skeptic feel free to ignore.

Honda’s power unit struggles stem from a cascading interaction between Aramco's synthetic fuel chemistry, 2026 engine regulations, and mechanical chassis integration.
1. Synthetic Fuel Chemistry & Pre-Chamber Sensitivity
Supplier Transition & Fuel Synergy: Switching to Aramco's 100% sustainable synthetic formulation (Aramco ProForce+) forced Honda to rebuild years of empirical dyno calibration previously optimized around ExxonMobil chemistry.
Flame Speed & Atomization: Synthetic hydrocarbons exhibit lower laminar burning velocities and distinct evaporation profiles, directly altering flame front propagation inside the cylinder.
Turbulent Jet Ignition (TJI) Limits: F1 pre-chambers rely on precise micro-atomization. Unpredictable synthetic fuel vaporization causes the pre-chamber flame jets to fire unevenly into the main cylinder, preventing a rapid, uniform burn front.
Knock & Auto-Ignition Margins: Lower knock resistance under 2026 compression ratios forces engineers to retard ignition timing and enrich air-fuel mixtures, cutting thermal efficiency and top-end horsepower.
2. Removal of the MGU-H & Pressure Dynamics
Loss of Turbo Speed Control: The elimination of the MGU-H under 2026 rules removes active electrical speed control over the turbocharger shaft, leaving intake manifold pressure unbuffered.
Transient Pressure Spikes: Sudden throttle transitions create air density fluctuations in the intake plenum, disrupting the pre-chamber's fragile fuel-air balance.
Energy Flow Restrictions: Under the 3,000 MJ/h total energy displacement limit, combustion inefficiencies can no longer be offset by increasing fuel mass flow, heavily penalizing energy density mismatches.
3. Harmonics, Cyclic Dispersion & Vibrations
Uneven Cylinder Pressure: Stroke-to-stroke burn rate variances (cyclic dispersion) across cylinders produce erratic peak pressure spikes.
Torsional Vibration: As reported by The Race, these inconsistent combustion pulses induce severe high-frequency harmonic vibrations along the crankshaft.
Reliability Feedback Loop: Mechanical vibrations transfer into the chassis, damaging onboard electronics, sensors, and battery components. To avoid structural failures, Honda is forced to run detuned, conservative engine maps.
4. Packaging Constraints & Thermal Management
Chassis Integration: Tight packaging around the Aston Martin AMR26 sidepods and engine cover restricts cooling airflow across the power unit cylinder heads.
Heat Accumulation: Reduced thermal margins increase heat retention within the combustion chamber, compounding knocking risks and locking the engine into an unstable combustion loop.

So I guess your saying, we should give up on Honda cause all the ADUO extra funding and dyno time is going to Honda and Aramco is the problem. so no mater how much Honda work on this they don't have the ability to fix the problem.

BTW those all sound like excuses that someone would make that started on their homework late. A bunch of problems they needed to fix, that everyone else already did.

[ispano6]

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So I guess your saying, we should give up on Honda cause all the ADUO extra funding and dyno time is going to Honda and Aramco is the problem. so no mater how much Honda work on this they don't have the ability to fix the problem.

BTW those all sound like excuses that someone would make that started on their homework late. A bunch of problems they needed to fix, that everyone else already did.

I guess you're entitled to your opinion. I'm just accumulating the known issues and putting it out there for the objective minded to parse and consider. Honestly, I'm trying to get to the truth of the matter. You seem hell bent on calling out how embarrassing Honda is. People should know they were asked to join late and started later than others with a cost cap already in place. You seem to want to discount the circumstances of which they joined, specifically Aston asking them after they had already decided to disband the previous team and were in maintenance mode.
Not going to reply to your comments anymore.