Hopefully this video should answer your question nicely
2006 Cosworth V8
The fact that there are two fewer pistons helps matters, but the main reason for the increase over last year is just natural development. There's also been more of a push to get the max power out of the V8s this year because of the huge drop off of performance.
The torque is also terribly low now (hence all teams now run 7sp 'boxes instead of a few still running 6 ratios last year). The quoted torque of 209lb/ft on LFS will be pretty accurate. Just to put that in perspective, our Saab 9-3 produces 205lb/ft of torque! It's all about top end power with an F1 engine.
Incidently, came accross this cool video in my search
Renault V10. I was lucky enough to see Mercedes run one of their V10s on a dyno in 2001, and it was pretty magical