A microprocessor controlled portable instrument for quick and simple recording of combustion pressure cycles in combustion engines. The evaluation of the data is carried out with a PC-system. The data recorded by this indicator are transmitted via serial interface to a PC. *Graphic display of recorded values for each cylinder *Computation of mean indicated pressures *Computation of the power of each cylinder, as well as for the whole engine *Graphic display of indicator graph (p-V graph) *Zoom and shift function for detailed display of any portion of the graph *Output of any graph to a PC printer *Saving of all recorded and engine data on mediums or hard disk *Export of data in ACS II format, for further processing on any standard software, e.g. Excel