Engine dyno software. Anything good on the Internet?

Yup. And that's just for the camshaft... There's the same issues with all the inputs that are not empiracle. Things like manifold choices, exhaust choices, etc. This is the price paid for ease and simplicity. I'm not saying it's right or wrong - just pointing it's existence out. I paid hundreds for the programs I have and I still consider the results only as trends. It's just too complicated to accurately simulate on a home PC.