McLaren still eyeing a podium finish in 2015

The Honda-powered team has managed just five points in nine races and is second to last in the constructors' championship, only ahead of Manor.

Its season has been plagued by problems with the Honda power unit, but Boullier is sure once the Japanese engine works at its full potential, McLaren could be in the hunt for a podium.

"I am repeating myself: if we can unlock the potential we will maybe be fighting - with some luck - for a podium," Boullier told the official Formula 1 website.

"If you can deploy your MGU-K power on the straights on every lap, that is worth a lot of time. Today we can't do that."

He conceded McLaren and Honda were simple not strong enough right now, but remains convinced that it is just a matter of time before they take a big step forward.

"We are not ready, we are not doing a good enough job right now - but we know that we have a lot of potential in our car," Boullier said.

"Just give us time. Once we've solved some of the reliability issues we will make absolutely significant steps forward."

He added: "We know that our cars have not tenths but seconds of potential that can be unlocked.

"We cannot physically use that because we have reliability issues, but if we overcome those we will be able to make major steps forward, believe me."