Dr Helmut Marko has admitted that Red Bull Racing won’t be able to compete with Mercedes and Ferrari until the end of the season.
Marko said that it was unlikely that Renault would be able to match the horsepower numbers of the Mercedes and Ferrari-powered cars before later in the season.
"Realistically, it will be only at the end of the season that we will have the power numbers of Mercedes and Ferrari," he told the Wirtschaftsblatt newspaper.
"We have made every effort to put together the best chassis. But motorsport without an engine is difficult."
Marko added that before Renault can put down the throttle in terms of performance, it needs to get to the bottom of its constant reliability troubles.
"It is important for the next race to at least achieve a certain amount of reliability," he said.
"Only then do you work on driveability, and finally the power."