May 11, 2021

How Honda achieved a win-win with its smaller and more powerful new F1 engine · RaceFans


Changes to the technical regulations during the winter are one part of the reason why Red Bull replaced Mercedes as the team to beat on outright speed at the opening round of the 2021 F1 season.

But as Mercedes team principal Toto Wolff admitted, there has been a shift in the balance of power between F1’s engine manufacturers as well. “We’re losing a little bit on the engine side,” he conceded after qualifying in Bahrain. “Honda has done a great job.”

At the launch of AlphaTauri’s AT02, the first Honda-powered car to break cover this year, technical director Toyoharu Tanabe hinted at the gains they had made over the winter through revisions to their engine, turbine and energy recovery system. Further details of those changes were revealed in a programme aired by Japan’s government-owned broadcaster NHK, which was granted access to Honda’s F1 engine development facility at Sakura.

When the pandemic struck last year, Honda initially opted to delay its next new power unit design to 2022. But the brand’s subsequent decision to call time on its latest spell in F1 at the end of this year led the team to re-commit to a 2021 deadline for its latest V6 hybrid turbo.

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Reliability was a significant weakness for Honda when it returned to F1 with McLaren six years ago. It has made great gains since then, and last year Honda was the only manufacturer whose drivers completed the season without exceeding their allocated number of power unit elements (they did begin fitting a new power unit to Pierre Gasly’s car in Turkey, but abandoned the change, which did not stop him incurring a penalty).

With the number of races on the 2021 F1 calendar increasing to a record-breaking 23, Honda targeted further durability improvements both to see out the season and provide the opportunity for performance gains.

To do this, it developed a new coating for the engine’s cylinder heads to improve their resistance to the high temperatures and friction generated during combustion. This innovation, which has made the cylinders up to 10 times more resistant than those used in Honda’s high-revving motorcycle engines, was evaluated at the end of the year at Yas Marina.

Once validated, the more robust cylinders allowed the team to seek greater performance from its engine. This was done by reshaping the combustion chamber to increase compression, by reducing the angle at which the valves are positioned. This proved to be a win-win development: the camshafts were moved closer together, producing a more compact engine, which is easier to package within an F1 chassis.

These gains came with a downside, however. As the unit performed more efficiently, less energy was lost through the exhaust system, which deprived the MGU-H of power. To solve this, the blades of the turbine were reshaped, enabling it to perform more effectively despite the reduced exhaust energy.

Further reductions in the size of the engine, and lowering of its centre of gravity, were obtained by introducing new construction materials. These allowed Honda to reduce the engine’s bore pitch (the gap between the centres of adjacent cylinders).

Pierre Gasly, AlphaTauri, Bahrain International Circuit, 2021
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Honda’s more powerful, compact and lighter RA621H power unit therefore ticks a lot of boxes for Red Bull and AlphaTauri. Its capabilities were demonstrated with pole position for Max Verstappen and fifth on the grid for Gasly’s AlphaTauri.

Neither quite hit the same heights in the race – Verstappen lost out to Lewis Hamilton’s Mercedes and Gasly’s evening was compromised by damage. But the drivers were quick to praise the latest developments from Sakura – Verstappen said Honda’s engineers had “a great winter”.

There may yet be some concerns over reliability, however. Troubling signs in the data from Sergio Perez’s RB16B and Gasly’s AT02 in Bahrain led to new electronics and batteries being fitted to both. Whether Honda’s gains have come at the expense of its 2020 reliability record remains to be seen.

Thanks to Daniel Bialy for his contribution to this article.

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