The members and users of TeamBuick.com have been given a RockAuto.com discount code to use on one order before September 21, 2021. When you see the "How did you hear about us?" box, plug in 392D10DD2B1820 for a 5% discount
I use Dyno2003. It was free, but I can't remember where I got it anymore. It takes a while to learn and there are a few bugs you have work around, but the simulation is very close to actual numbers of engines I have had dynoed. The power curve is very representative, and the HP numbers were with in 10HP. You can change the cam, air flow and compression for a given combination to see the effect on the power curve. Then you can overlay them. I think it was worth the time to figure out. I am sure there are better ones available for other concerns like asymmetrical cams, octane usage and parameters like runner volume and length. The other issue is that it will not rule out the impossible if you choose it. You can use it to simulate a 15:1 compression engine with an early closing intake valve event that we all know will detonate. You have to be aware of certain limits when using the program as it is not. I use the DCR calculator from Pat Kelley to help me decide if a given combination is reasonable for a given fuel octane when looking at possible combinations for simulation in Dyno2003.
This is not a simulator, but I recently picked up Dynolicious for my I phone. It uses the accelerometer in the phone to calculate 1/8 and 1/4 mile times in relation to weight and drivetrain loss for a given vehicle. I am still trying to get it to work, but it is reported to be close to actual times recorded by the vehicles. I will have to report back later.