McLaren racing director Eric Boullier has revealed the team is "two weeks" behind schedule with next year's car as a result of the late engine decision.
McLaren announced on Friday that they were splitting with Honda and swapping to Renault power in 2018.
The announcement came after weeks of wrangling between Honda, Renault, McLaren and Toro Rosso, who will be taking Honda engines from next season.
And although the deals were concluded later than McLaren had hoped, Boullier says next year's preparations were only delayed by about two weeks, and it is time that he is confident McLaren can make it.
"Obviously it's a challenge," he said of the delay.
"Now we have to be [working] 24/7 I would say to try recover a couple of weeks where an ideal decision could've been taken.
But, two weeks is recoverable, it won't be any compromise next year.
"Of course, we don't have the same experience as some of the customers, so we have to discover the package.
"But, I think we can trust our engineers to do a very good job and two weeks are recoverable, but this is going to be a huge load of work and I'm glad to see there's a lot of energy going inside McLaren to try and recover as fast as possible."
The racing director also refuted suggestions that it would have a negative impact on the development of this year's car.
"No," he said. "It doesn't mean that at all.
"It just means we are increasing the workload to make sure we can recover, and once we recover we will go back to the standard way to work.
"We have a different process today about work, because of next year's car, despite the change of power unit, it's an evolution so there will be no revolutions. That doesn't change the way we work."
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