Red Bull motorsport boss Helmut Marko is calling on F1 to introduce an independent engine supplier as soon as possible, claiming the future of the energy drinks teams is uncertain without it.
F1 sporting director Ross Brawn is hard at work defining the magic formula for the future beyond 2020 when the sport's current regulation agreements expire.
Brawn's quandary is finding the right compromise between a financially viable power unit and one that retains relevancy with the automotive industry.
Marko is expecting a platform to be specified by the end of this year but also believes an independent supply is crucial to Red Bull's team and to the sport.
"The latest must be 2021 that an independent engine supplier comes into F1, Marko told the official F1 website.
" This is more than necessary - and the engine has to be simple, noisy and on the cost side below 10 million.
"We are talking about a much less sophisticated engine to what we have now - a simple racing engine. There are enough companies around that could supply.
"So we expect from the new owners together with the FIA to find a solution at the latest by the end of this season. If that doesn't happen our stay in F1 is not secured."
At the height of its acrimonious relationship with Renault in 2015, Red Bull also said that its presence at the pinnacle of racing was not guaranteed.
Renault's progress since then has been solid, although Marko believes that Red Bull is still suffering from the relative deficiency of its power unit compared to rivals.
"We have two problems: Renault had some reliability issues, which have slowed them down in the development, and we didn't deliver the chassis that we should have done," Marko said.
"But we are working day and night to pick up our shortcomings. We are pretty optimistic that we will make a significant step forward in Barcelona where a big change of parts is coming.
"So sometimes patience is the best virtue a driver can have!"
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