Computer dyno simulation and engine building software

A very important thing to understand about dyno simulation software is that it is only as accurate as the inputs you give it.  Because of that, its very important that you read all of the documentation associated with the software.  Each one is different and requires the user to know its finer points.  For instance, when using Desktop Dyno 2000, one must know how the software simulates cam lobes.  You have the option of entering the cam timing as seat-to-seat or as .050" timing.  Then you select the lifter type.  For the casual user who is simulating (for instance) a stock Olds 307 with a roller cam, one would assume that you should enter the cam specs and a roller lifter.  The problem is, DD2000 uses the lifter type to assume the lobe profile aggresiveness.  A roller lifter typically has the most aggressive ramps, but not in the case of stock smog cams.  If you read the instructions you will find that a more accurate simulation could be had by simulating it with a flat lifter and used seat-to-seat timing which would more accurately demonstrate the lobe profiles.  Reading the documentation associated with the software will help you to understand the subtleties of the program and improve your predictions.

As a good primer, try to duplicate known combinations.  For instance, attempt to use the software to duplicate the torque and hp peaks of a GM goodwrench 290hp crate engine.  The first few times you'll probably get results that are way off.  Play around with how the settings actually affect the outcome.  Once you've mastered duplicating known combinations, you can start accurately predicting your own builds.