Renault engine “two to three years” behind – Horner

Red Bull team principal Christian Horner believes it will take “two to three years” before Renault can compete with Mercedes and Ferrari in terms of power unit performance.

The French constructor and Milton Keynes-based outfit enjoyed a very successful run with the normally-aspirated V8s, claiming four consecutive double championships between 2010 and 2013.

However, the situation started deteriorating quickly in the wake of Renault’s troubles in the new 1.6-litre V6 turbocharged era, with Red Bull’s senior management increasingly criticising their long-time engine supplier.

Growing frustration has culminated in an early split between the two partners, and though the energy drinks giant is yet to secure a replacement for 2016, Horner insists his employer made the right call.

“Since the power unit regulation change, it's a very different world that we're living in,” he told Sky Sports F1. “There are really only two engines out there that you can compete for grand prix victories with and, unfortunately, Renault have fallen behind that.

“It looks like it's going to be at least two to three years before they can be in a position to compete again. As a paying customer, we can't afford to wait that long.”

• Red Bull: Burning bridges everywhere

Red Bull initially tested the waters with Mercedes in order to get its hands on the dominant PU106B power unit but was met with an official refusal, which leaves Ferrari as the sole viable option for the Austrian company.

But while Maranello is open-minded about welcoming back Red Bull and Toro Rosso to its fold, it appears more reluctant to grant them the works-outfit engine parity they are seeking.

Asked by Sky Sport F1 whether he fears Red Bull’s public slating of Renault might deter other engine manufacturers from teaming up with the four-time world champions and their sister squad, Horner replied:

“I doubt it. Perhaps we have been guilty of being honest, whether that is my comments or Adrian Newey's comments or Helmut Marko's or most important of all [Red Bull team owner] Dietrich [Mateschitz]'s as he is paying the bill at the end of the day.

“I don't believe that would have an impact on influencing any other supplier.”

Red Bull has repeatedly claimed that they would walk away from F1 should they fail to be provided with first-class power units.

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