I am doing an acceleration study of a passenger car and I keep getting a "Threw a rod" error message if I don't shift the gear in time in my SIMON event. I want to try to maximize the RPM before I shift gears. Is there an easy way to do this?

Yes there is!  Use the Automatic Transmission model and set the shift points at the exact RPM you want.  To change from manual transmission to automatic transmission, go to the Vehicle Editor and click on the engine icon of the vehicle.  In the Powertrain dialog, click on the Transmission button.  In the Transmission Data dialog, change the type from Manual to Automatic and adjust the shift points accordingly. When you rerun your SIMON event, your transmission will shift gears automatically, allowing you to focus your efforts on studying the acceleration capabilities of the vehicle.