Sauber says that the decision to delay using Ferrari's upgraded engine until the Belgian Grand Prix is a strategic one aimed at helping it end the Formula 1 season on a high.
Although the Ferrari works team has used development tokens to improve its power unit in Montreal this weekend, Sauber said it was holding fire on changing its specification for now.
In fact, the team will wait until the Spa race after the summer break – when it also plans to introduce some aerodynamic upgrades – to go for a better power unit.
Sauber team principal Monisha Kaltenborn made it clear that the decision was made for sporting reasons, and that there were no financial considerations at play.
"It is nothing to do with financial," she said. "That is the strategy which has been chosen for when you want to introduce what engine you want to use when."
Keeping its power dry for Spa
Kaltenborn said that waiting to make the most of potential improvements should pay dividends in the closing stages of the season because it would likely ensure a bigger step forward.
"The issue is when do you introduce a new engine?" she explained. "We are on our second engine and they [Ferrari] are getting in their third engine.
"Obviously they have a different strategy, and may need to return to an older engine, but that is a different approach to things.
"The other thing is that development is ongoing. Maybe we can get more when it [power] really matters: and Spa is a race where it really matters.
"Here [in Canada] is fine and the next one coming is also alright. But Spa and Monza are the ones where you can really feel the upgrade, so maybe there is more to come."