Honda has revealed that its second ADUO development step was introduced earlier than many had realised, with Lance Stroll receiving the revised turbocharger at the Spanish Grand Prix in Madrid before Fernando Alonso used it in Baku. Honda Racing Corporation president Koji Watanabe has confirmed that the Japanese manufacturer changed its original upgrade schedule, separating developments that had initially been expected to arrive together.
The revelation comes as Yoichiro Fukao officially takes over leadership of Honda’s Formula 1 power-unit project from Tetsushi Kakuda on October 1, with attention now turning to how much performance can still be extracted from the RA626H V6 and its revised turbocharger.
Honda changed its original ADUO upgrade plan
Honda altered its programme in a somewhat unexpected way. It had been thought that the Japanese manufacturer had approved the RA626H with all the changes permitted by the FIA through the ADUO mechanism for the Dutch Grand Prix at Zandvoort, after Aston Martin introduced its heavily evolved AMR26 in Hungary.
That was not what actually happened.
Development of the evolved power unit was running behind schedule following a disappointing shakedown at the Hungaroring, carried out alongside the Pirelli 2027 tyre test. Honda therefore decided to split the two development opportunities that had originally been expected to debut together at Zandvoort.
The turbocharger changes supplied by IHI were subsequently postponed. Lance Stroll received them at the Spanish Grand Prix in Madrid, while Fernando Alonso had to wait until the Azerbaijan Grand Prix.
Aston Martin initially ran combustion upgrade without revised turbo
That helps explain the difficulties experienced by both Aston Martin drivers while using a power unit that had been updated in the combustion chamber but was still running the previous turbo specification.
The result was serious drivability problems, particularly during downshifts and when using engine braking. Those characteristics made the AMR26 unstable under braking and left Aston Martin well below the performance level it had expected after redesigning significant elements of the car according to Adrian Newey’s technical direction.
Koji Watanabe has now acknowledged that Honda’s second Additional Development Upgrade Opportunity was delayed relative to the original timetable.
Koji Watanabe confirms Lance Stroll received new turbo in Madrid
Watanabe confirmed that Lance Stroll had access to the revised turbocharger in Madrid, while Fernando Alonso only received the same specification in Azerbaijan.
“We introduced the first ADUO update in the Netherlands and then installed a power unit with the second update on Stroll’s car at the Spanish Grand Prix,” Koji Watanabe explained.
“The unit used in the Netherlands had drivability problems, so we introduced an improved turbocharger at the Spanish Grand Prix to try to resolve the issue.”
When asked whether reducing turbo response delay had been one of Honda’s objectives, Watanabe gave a direct answer.
“Exactly.”
He then explained why the two developments had not appeared together.
“Ideally, we should have introduced everything at once, but the priority was to launch Spec 2 of the engine in the Netherlands. At the same time, we were working on countermeasures for the turbo lag, and that update was introduced in Spain. It was simply a staggered implementation.”
Honda believes more performance remains in its 2026 power unit
The results Honda hoped to achieve have not yet fully materialised, however, and Watanabe believes there is still more performance available from the package.
“I don’t think we have fully exploited the performance of the PU yet; I believe there is still room to improve our competitiveness.”
Watanabe compared the current process with Honda’s previous work during its period supplying Red Bull.
“When we supplied engines to Red Bull, although genuine hardware upgrades were not permitted, we carried out simulations to check the operating limits, increasing performance year after year. It was a process of ‘reliability development’.”
The implication is that Honda believes greater performance can still be extracted from the existing specification by progressively understanding and extending its operating window, even after the hardware developments introduced through ADUO.
Yoichiro Fukao takes charge of Honda’s F1 power-unit project
The programme is also entering a new management phase. Tetsushi Kakuda officially hands leadership of Honda’s Formula 1 project to Yoichiro Fukao on October 1, with the former deputy project leader stepping into the top role.
The change comes after a difficult first season for Honda under Formula 1’s new power-unit regulations.
The current RA626H retained significant conceptual links with the Honda engine architecture that helped deliver four world championships, but the new generation of power units has introduced a much more extreme balance between the internal-combustion engine and electrical contribution, together with major changes around the combustion process.
Honda believes the leadership transition at Sakura can inject fresh energy into its work towards 2027, while the immediate challenge remains addressing the limitations of the current power unit, which continue to restrict the development potential of Aston Martin’s revised AMR26.
Sepang could provide clearer measure of Honda’s progress
The confirmation of Fernando Alonso and Lance Stroll for next season should provide greater stability inside Aston Martin as the team works through its current technical problems.
Sepang should also offer a useful opportunity to assess the complete Honda package on a circuit that is less extreme in its power-unit demands than some of the venues Aston Martin has recently visited.
With both drivers now having access to the revised turbo specification, Malaysia could provide a clearer indication of the competitive level Honda has reached with the updated RA626H.
Significant work nevertheless remains. The estimated power deficit is still described as being around 60 horsepower, meaning the revised turbocharger and combustion updates have not yet transformed Aston Martin’s competitive position.
For Honda, the next stage is therefore about extracting the full potential of the hardware already introduced while the new leadership structure begins preparing the programme for 2027.
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