This paper describes a procedure used to aid in the control of IC engine knock, an autoignition phenomenon that results in customer annoyance, loss of power, and potential engine damage. Since a control system can only function as well as the signal it is provided, input signal optimization is critical to the robustness of the system. Optimization of the input signal starts with a properly located physical transducer on the engine block. The locating process begins with laser holometry to evaluate compliant regions of the block. Holographic data, block vibration spectra and empirical engine data are then used to identify the most promising sensor locations. These locations are then verified with a broadband accelerometer mounted on a dynamometer engine. This process allows the highest available signal to noise locations to be found in a systematic and efficient manner.