BMW canned P85 over rules

Theissen blamed the short lead-in time for the change in policy and instead the manufacturer will use an evolution of its P84 engine for the BMW Williams team's 2005 campaign.

"This year's engine is a development of last year's P84," said Theissen. "We had a quite aggressive development programme running on the P85 but with the announcement of the two-race rule, we decided to go back and adapt the P84 to our requirements.

"The critical components are the moving parts that endure a high mechanical and thermal load, particularly the crankshaft drive and valve gear. Each of these has been redesigned for a double life span, which normally means a bigger and heavier engine, costing speed and power. We have been meticulous to try and minimise these losses."

Theissen, like Frank Williams, was disappointed with the BMW Williams team's results in 2004.

"For four years we surpassed our targets," he said. "Then in 2004 we found ourselves in a trough, failing to meet our expectations for the first time. We now aim to accumulate successes once more with renewed strength.

"We have managed to build this engine without adding too much size and weight. We will carefully choose when to run top revs but I think we will end up the same as last year. I think we'll start with a slight drop of power to start with but we hope to be back up that level by the end of the year."