Sauber team principal Monisha Kalterborn has confirmed the team will use a 2016-spec Ferrari power unit next season.
Kalterborn said the decision had been taken earlier this year in order to allow Sauber to focus on its chassis design and development, ahead of the new technical regulations which will be introduced for 2017.
Had Sauber opted to overhaul its power unit, the Swiss team would have risked being forced to make late changes to its car design. As a result, it has elected to remain with a known engine concept in the shape of a 2016 Ferrari power unit.
"We will be using the latest spec of the 2016 Ferrari engine in 2017," Kaltenborn told F1i.
"The reasoning is actually that we took this decision a while ago -- not just recently -- at a time when actually the rules for next year were also not 100% clear. At that point of time we took a strategic decision to say that we want to focus the resources we have on chassis development, on performance development and in a way leave the engine side to the information and the areas which we know.
"So it was a pure strategic decision taken even before the rules for next year were actually finalised."
Kalterborn refuted claims that Sauber's decision was based on delays to its 2017 developments and insists the team -- which was taken over by Longbow Finance in July -- is well on course with its plans for next year.
"Any statements being made that this was taken because we are apparently in delay with our developments are wrong. We are absolutely on plan, we have not suffered any delay there. Through the change in the ownership now of course we have the stability and the boost you need to step up the speed we're developing at."
She added: "Obviously there's not going to be that development on the engine side but in our view it's the right step we've taken that whatever we might suffer on one side we are confident with the additions we have to the team to be focusing on compensating for that on the chassis side."
Kaltenborn said the judgement was not influenced by Sauber's financial situation, and used Toro Rosso, who are running a year-old Ferrari power unit in 2016, as an example of how it is possible to compensate for a lack of power unit development over the course of a season.
"It's a wilful step we have taken here. It did not have anything to do with any financial constraints, it was really that we want to focus on the chassis development. Our engineers are convinced that if there is any disadvantage you might have in terms of the power unit they want to compensate it through the chassis development.
"Well we definitely looked at [Toro Rosso] but for us the decision was really taken a while ago because things were not 100% sure on the rules. We wanted to have the ability that if there is any change again we can react to that and the power unit side is then the known side for us."