Williams Want Engine Decision this Month

"I would like an answer by week 30. We are now in week 26," he told reporters at the French Grand Prix.

BMW motorsport director Mario Theissen said the Munich-based carmaker, who have been Williams' Formula One engine partners since 2000, had just started discussions with the team about continuing their supply. "We don't have a decision," he said.

BMW, who had an engine partnership deal with Williams until 2009, announced last month that they would take over the Swiss-based Sauber team from next January.

Williams said that decision had not hit them "like a bolt out of the blue".

"We knew what was coming, or might come, and we had plenty of time to persuade otherwise but we failed," he said.

BMW have said they are willing to continue supplying Williams, who have been talking to other engine makers since it became increasingly clear that the relationship was growing strained.

Theissen said that if the team decided to go elsewhere, BMW would not actively look to supply anyone else: "We wouldn't rush for another customer."

Same Engine

Williams' Australian driver Mark Webber said before Sunday's race that the team should move on rather than accept a second-string arrangement.

"I think what he means is that if it's not going to work, because BMW are going to do their own team, maybe a fresh start might be a good opportunity for Williams to start all over again," said Williams.

Williams have won nine constructors' Championships and seven drivers' titles since 1980 and the team boss said he believed a non-manufacturer team could still be successful in a sport increasingly dominated by major carmakers.

"Mario has said several times that it is just too complicated to make a best engine for one's own race team and a downgraded engine for the other team," he said.

Theissen agreed, particularly with engine rules changing next year from a three-litre V10 format to a 2.4-litre V8 -- although teams are allowed to continue with rev-limited V10s as a cost-saving measure.

"You might be able to (supply different engines) and it might be cost-saving at first because you might have some V10 engines in stock," he said.

"But to run a complete, competitive season you would have to develop the V10 as well as the V8 and you would always have to make fresh engines. It doesn't really make sense."