A versatile data acquisition system for engine pressure-time history is described. The on-line system utilizes a 12-bit sample-and-hold A/D converter in conjunction with a mini-computer. The computer controls the acquisition process and performs data processing to generate the desired results. The time base for the system is generated by a shaft mounted disk and photoelectric sensors. On-line selection based on predefined criteria of particular interest is software implemented. Statistical data are available such as the standard deviation and the histogram of maximum pressure. Teletype print, XY plot and punched paper tape are standard outputs.Among the wide variety of potential applications of this system, some actual examples in such areas as cyclic variation, knock, friction losses and heat transfer are given.