I read that some especulations about BMW engine that it reaches 890 HP, and Ferrari something like 875-880, but u got to see that BMW uses it's engine in max power, this is why they have so much problems, Ferrari because their new gearbox they make faster gear changes, they don't uses the engine in full power, this is why they don't reach 885 or even 890.
I think this year no engine has less than 820 HP, also Jaguar has the new version of Ford engines, this is why their engine are more powerfull than Arrows (I think since Barcelona they had an old version 'cause the team hadn't money to buy for the new one).
For Mercedes and Renault I have no Idea, about Toyota I have a magazine that I got in one exposition from Toyota that they said their F1 engine has about 850HP.
See u,
Vantoil Jr.