Never heard of dynosim, but you can download desktop dyno for free. I dont remember where I downloaded it at but Im sure someone around here does. The program is alright, gives you a decent estimate of power output but not all that accurate. There are too many variables, tempature, fuel ratio, etc. that the computer doesnt factor. Nevertheless they are really fun to play with though, its fun to build some crazy big block making outrageous numbers. Then dream about how much fun that would be to have in your rig.