Unbranded engine for Red Bull?

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Red Bull Racing's quest to seal an engine deal for 2016 has yet to come to fruition with the Milton Keynes outfit now running perilously close to a practical deadline by which its future needs to be secured.

Both Ferrari and Mercedes have declined to partner with Dietrich Mateschtz's team, while Honda appeared keen on a deal only for its McLaren partner to veto the idea as Ron Dennis looked to protect its exclusive collaboration with the Japanese manufacturer.

The fact that there is no love lost between Red Bull and its current engine supplier Renault, on the back of a dismal season and several public spats between the two partners, means a continuation of the working relationship appears almost impossible.

Renault may however still be open to the idea if it can enforce its own stringent conditions. The French company's CEO Carlos Ghosn would commit to a deal providing Red Bull agrees to the hefty price tag demanded by Renault, and the supply may involve unbranded power units as hinted by Christian Horner in Mexico, although he would not name the manufacturer.

Red Bull owner Mateschitz had initially set an October 31st deadline by which an engine agreement had to be signed. Designs for 2016 are now well under way at the majority of F1's teams, so Red Bull's plans are overdue as the team faces a crucial few weeks ahead to get its affairs in order.

Mateschitz has now set the ultimatum at the weekend before the Abu Dhabi Grand Prix on November 21-22 to sign a deal with an engine partner and keep it on the grid for 2016.

“At the moment we are right on the limit to be at the first test,” Horner explained.

“The team in Milton Keynes have demonstrated their ability to work to massively tight deadlines, and I am sure we will be able to meet whatever targets we need to, as long as we come to a decision in the next couple of weeks.”

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