Abstract: A system and method are disclosed for motoring an engine using an external drive motor for the purpose of performing tests on same. The system and method is capable of operating in three separate modes, a horsepower testing mode, a valve train testing mode, and a lap simulation mode. In the lap simulation mode, for example, the operator may select by way of a computer how many laps are to be run, the length of each lap, and the exact RPM to be used during each second or time period of every lap. In such a manner, the operator may simulate actual races so as to determine how a particular engine or components thereof will stand up to anticipated racing conditions. Another aspect of this invention is the use of a laser affixed to the block for the purpose of measuring vertical valve movement during motoring of the engine. The use of such a laser overcomes numerous problems in the prior art caused by vibration, lighting, etc.