Toro Rosso Technical Director James Key has revealed he has had to re-design the internal layout of the 2018 car in order to fit the Honda engine for next season.
The Briton is known for designing very strong cars aerodynamically, with the Italian team shining in Monaco this year and Carlos Sainz finishing fourth in the wet in Singapore, but there was controversy with former supplier Renault in Brazil, who suggested the packaging of the STR12 was to blame for the number of reliability problems they had.
Now with a new power unit to install into his next creation, Key praised the effort of Honda, who had to work to a 'size zero' philosophy at McLaren, but admitted it is a challenge to accommodate it.
"They are completely different," he told Autosport comparing it with Renault. "It's a very nicely packaged engine, but the whole power unit is a different architecture. It doesn't drop into the same space. There's quite a bit of car layout work that has to be done to adapt to it."
He would confirm, however, that task has not impacted the external design of the 2018 Toro Rosso.
"We try and stick to a rule that, if a car has already been in a development process for a while, not to upset any major items such as aero surfaces and that sort of thing, so we're not starting from scratch in too many areas," Key said.
"We've adapted the car under the skin as best we can and that's led to quite a different approach to the chassis design, to the way the gearbox works and so on. We've carried over the concepts and developed them further from this year's car."
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Expanding further on the changes to the transmission, he added: "Its layout and its size is different for this engine, compared to what we have this year. I think the concept is the same, but the architecture is different.
"Some internals will carry over, some will be changed, some will be bespoke to the STR box. Otherwise, it will be pretty close to what we've been running."
The internals of the gearbox is the only area where the team get help from their big brother Red Bull through the Technology arm of their Milton Keynes operation. Though known as the junior of Dietrich Mateschitz's two teams, Key actually expressed disappointment at the lack of independent recognition Toro Rosso gets.
"There's a lot more going on at STR than people think," he said. "People don't know STR, it's really frustrating.
"Although it makes a lot of sense to join together [with Red Bull] where you can, we've got our own aero department in Bicester, with our own wind tunnel, and that's entirely independent because it has to be legally.
"The entire design of the car is done in Faenza - the only bit of the car that comes from RBT is the gearbox internals which are jointly designed because there are often things that we specifically need."
