This is a project I've been working on for the past 2.5 years. I've developed software that allows you to input engine specifications and the code determines the engine performance. For now, it is free to use.
The web site describes in a lot of detail what the code does and what it doesn't do so you can judge for yourself if you are interested in it.
There is also a user's forum, linked on the web site main page, that is the portal by which you access the software.
Enjoy!
www.dynostep.com