Toro Rosso technical head James Key does not think the late change in engine supplier will have a significant impact on the team's 2016 campaign.
Despite previous concerns that the change would affect the team adversely during the pre-season, Key maintains that his team is well on track.
"The delay in the contract for the engine supply in the end turned out to be less dramatic than it might have been. The work is on schedule," Key told Autosprint this week.
Key does acknowledge that there were some complications when the change was implemented but insists that the change will benefit the team in the long term.
"The only serious problem was that, because of the features of the new power unit, it was not so easy to place in the car," added Key.
"Compared to the Renault, not only its size and configuration was different, but also the characteristics of the cooling system and electronics. We had to completely re-do the rear of the chassis," explained Key.
"In 2015, our chassis was quite effective and our main problem was related to the power unit. Only now, knowing the characteristics of the Ferrari engine, we realise how far behind we were in this aspect," he said.
Toro Rosso will operate with the 2015 Ferrari spec engine this season, which effectively means they are still well behind the top teams on Formula 1. However, that is a hit that Key is prepared to take at this juncture.
"Obviously the priority will be the 2016 Ferrari engine, because they cannot homologate two different engines. But we will be able to adjust the software," said Key.
The expectations remain high this season and anything lower than a fifth place finish will be a disappointment for the team. Last season Toro Rosso finished seventh.
"Last year, they [the drivers] did a great job but did make some mistakes. This was understandable as rookies, but now I'm expecting further progress from them and no excuses," said a confident Key.
"Everyone understands that we must achieve better results. When I moved from Sauber, I did not realise that Toro Rosso was as big as it is – it has always been in the shadow of Red Bull.
"Our expectations are high and everyone understands that we must achieve better results. We can't fight with Williams but I think we can with Force India – last year Sergio Perez was on the podium so let's see if we can match that.
"Still, to achieve fifth position will not be easy."