Early engine deal a "massive" boost for Toro Rosso

The Faenza-based squad faced the difficulties of a very late switch to Ferrari engines at the end of 2015, a move that compromised its chances early on in 2016 as the new car had not been designed to accommodate the Italian power unit.

Toro Rosso will return to using Renault engines in 2017 as part of a deal that was announced in May.

Key admits that, having faced the challenges of fitting the Ferrari engine in such a short period of time, securing the Renault power unit so early is a big boost for its chances of hitting the ground running next season.

"Massive. It's very difficult to describe how big it is," Key told Motorsport.com about the difference it makes to have its engine supplier confirmed so early.

"We are really happy to know which engine we'll be using now. That was a very tough situation with this car.

"We were very late with the Ferrari engine. We didn't really have any information about the Ferrari engine, so we sat down with them in December and discussed things, so it was extremely late.

"The fact is you build the architecture of your car around the power unit installation, and it's so complicated now. It's so much trouble. An optimum car is based around the integration of the power unit."

Ferrari engine compromise

Key conceded that this year's STR11 was inevitably compromised as a result of the late deal with Ferrari.

"We tried to minimise the impact of that, but inevitably there are knock-on effects," he said. "The car was a bit too heavy at the start of the year. We had some issues with some of the cooling parameters.

"Many other things weren't optimum, we had to make some guesses in some places. And it costs you a lot of money as well. To do that in such a short space of time costs you a lot of money.

"There are many, many things which even if it's difficult to tell when you see the car on the track, actually you know what's wrong with that car because you've had some compromises."

The Briton added that Toro Rosso is making good progress with its 2017 challenger, but admits that is hard to judge given the big regulations changes coming into play next year.

"I think it's okay," Key said. "We are sort of on schedule at the moment, although the schedules move depending on what you find.

"I know most people are pretty hectic now with their 2017 cars. It's very difficult to tell how you are doing because you don't know what other people are doing with the regulations.

"One of the hardest bits is knowing what makes a car with such massive regulations change tick. It's so difficult to tell at this stage.

"We are going down a route of really trying to understand what makes a good 2017 car and see if we can achieve it."

Interview by Oleg Karpov