Mercedes have explained just how much work was involved in their "massive" revamp of the engine for the 2022 season.
Whilst many changes as a result of the new technical regulations are visible on the car, the power unit is an area of development which remains unseen to most.
That does not mean it has been any less of a project, though, with Hywel Thomas, Managing Director of Mercedes AMG High Performance Powertrains, giving an insight into the process in a new video from Mercedes.
"Massive" project of reworking the engine
Thomas is pleased with the work that the team have put in to the new power unit, with the alterations going far beyond the usual "little rearrangements".
"There's just so much great work, I think, done by the team, especially [with] the way that it sits within the car," Thomas said.
"We all know how much work's gone in to get it into the car. The front of engine [is] just completely different. I guess over the years, we kind of talk about the front of engine, but almost every year, we're rearranging it.
"But this wasn't a little rearrangement. This has been a massive terror!"
Thomas acknowledges that the work involved has been worth it, adding: "But it's to make it look like that, isn't it? So we all understand.
"And [with the] exhausts, again, I guess it's another one of those items [where] you kind of look at it every year, and we tweak it here, we tweak it there. [But] what's under there is completely, completely different."
Viewed by others:
Impact of fuel changes
Another area of the rule changes to have an impact on the process of building the new engine has been the move to the more sustainable E10 fuel.
"The sustainable element [...] changes the combustion," Thomas explained.
"Putting ethanol into the fuel, it does just mean that the calorific value goes down. So from a starting point, you've kind of got less performance. So for the same amount of fuel that comes through, there's just less energy in it.
"That's a problem for us, because it's taking performance away. But then the fuel also [is] more knock resistant. So again, just the characteristic of that ethanol and dropping it is that the fuel will be more knock resistant, so then we can run the engine a bit harder.
"And it's about minimising one side, maximising the other, and making sure we get the performance back."
This is something that Mike Elliott, Silver Arrows' Technical Director, agrees is a "huge challenge".
Thomas added: "The number of candidate fuels that we've done, the number of different blends that Petronas brought - it was a big part of the development this year."
Added factor of engine freeze
In addition, the introduction of the engine freeze in 2022 - meaning that development will be frozen until 2025 - has provided another issue to consider.
"Then on top of [the other regulations], you've got the fact that it's frozen," Thomas said.
"That's the PU for the next four years. We didn't want to leave anything out. Everything had to get in there - all the performance ideas, all the reliability ideas.
"That's why we've ended up - if you look at the parts counter of what's carried over - not that far off [the aerodynamics team]. It's definitely the biggest change that we've done since this regulation."
F1 Podcast: All you need to know after the first pre-season test
At the end of the first pre-season test of 2022 in Barcelona, Dieter Rencken and Thomas Maher discuss the on- and off-track developments so far.