Red Bull: Christian Horner wants quick Renault engine changes

Christian Horner has grown impatient of engine struggles

Red Bull have urged partner Renault to push through improvements it has found on its engine in testing.

Team principal Christian Horner admitted Renault's failure to close the gap in engine performance with Mercedes and Ferrari "tests our patience".

Horner believes it would take "two or three months" to incorporate the progress onto the engine.

"It needs to happen this year - but also what you learn this year will help you next season," he said.

The Renault engine is at least 50bhp down on the best engines.

"Like any competitive team we want performance yesterday, and unfortunately with engines the lead time is a lot longer than with the chassis," Horner told the official Formula 1 website.

"Patience is something that we are not really good at. We want to have performance as soon as possible."

Red Bull and Renault won four consecutive world title doubles together from 2010-13.

But the relationship has been tense since the start of last season, when it became clear the French manufacturer had been left behind in developing the new turbo hybrid engines that were introduced in 2014.

Red Bull has consistently criticised Renault's lack of performance in public, with owner Dietrich Mateschitz saying last month that it was draining the company's "will and motivation" to stay in F1.

The two are contracted to remain together until the end of 2016, but many F1 insiders believe that a split is inevitable after that.

Red Bull's relationship with Renault as engine supplier goes back to 2007

Horner acknowledged Ferrari president Sergio Marchionne's offer of an engine supply in the future should Red Bull need it.

"It would be an exaggeration saying that Red Bull is 'flirting' with Ferrari," Horner said.

"Obviously Red Bull Group had a relationship with Ferrari for many years as engine supplier for Toro Rosso.

"Sergio made a generous offer without any details when he attended the Austrian Grand Prix - but right now our focus is on what we have at this point in time."

Renault's future in F1 is in some doubt as it weighs up three options beyond 2016 - continuing as a partner for Red Bull, buying its own team - with Lotus the favourite - or pulling out altogether.

Renault previously owned what is now Lotus, until selling it to the Genii Capital investment group at the end of 2009.

Horner said: "Those are decisions that they have to make. It would hold a certain irony if they buy back the team they sold.

"But as far as our position is concerned, we have a very clear agreement with Renault, which guarantees us priority status. Any of those scenarios requires having a competitive engine - and doesn't really matter based on the agreement that we have."

Renault was not immediately available for comment, but Renault Sport boss Cyril Abiteboul said last month that the company would only stay in F1 if it could make its engine competitive.

"What we have to do is bring the engine to a competitive level because there won't be any future for Renault in F1 if we do not have a competitive engine. That is the first step," he said.