Honda Formula 1 chief Masashi Yamamoto expects "mixed feelings" watching Red Bull use their engine but without the branding after 2021.

Earlier this year it was confirmed the Milton Keynes-based outfit will take production of the power unit in-house after F1 agreed to introduce a freeze on engine development to reduce costs.

Although, while Honda is pulling out as an engine supplier, Yamamoto confirmed there will still be some co-operation between Red Bull and the Japanese manufacturer.

"We have [decided] the overall direction with Red Bull and we are now in the phase of sorting out the details of how Honda can support the programme from next year onwards. We’re still working that part out," he told Formula 1.com.

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"Personally, I’m really glad that at least from next year they have something that we have made.

"As Honda, we like to support Red Bull with what we can to give them a competitive power unit that means they can fight for championships. If we can give it to them then that would be really great."

Still, personally, Yamamoto admits not seeing the company name or logo on the 2022 RB18 will be tricky.

"There will not be any Honda branding on the car or the engine, so it will be mixed feelings seeing the car that has a Honda power unit," he added.

"The heart of the car is a Honda however it’s not really a Honda!"

Ahead of their departure from F1, Honda brought forward the introduction of a new power unit that had originally been delayed until 2022 due to Covid-19.

And so far, both the performance and the reliability have been impressive.

"Obviously we stopped a bit of the development of the engine because of the Covid situation – maybe for a few months – and then we brought it forward again to 2021, therefore it was very tight in terms of the timeframe. The engineers in Sakura did a very good job," Yamamoto explained.

“When you take into account the period we had available to us, it was very tough, but we have piled up lots of knowledge since 2015, so I trusted the engineers that they could do it.

"We were sure and we knew that this power unit has more power, therefore we wanted to race with a better engine with more power, so our determination was really strong."

Indeed, after Bahrain, the belief is Honda has completely closed what was a pretty substantial gap to Mercedes last year.

“I must say Honda did a fantastic job in Sakura because this new power unit is much more powerful and better drivable as it was in the past,” AlphaTauri boss Franz Tost said.

“I think that Honda is really very, very close to Mercedes and I can only say thank you to the Japanese engineers because they did a fantastic job.”