Relationship Among Harmonics from the Diagram of Pressure and Parameters of Operation of the Engine

From the pressure signal, in the cylinder of an spark-ignition engine, measured experimentally, we have obtained the variation of pressure due only to the process of combustion.

We have proceeded to the study of this signal using Fourier's analysis and we have obtained several relations between the harmonic's amplitude of the transformed and the engine's operation parameters. These relations can be used as tools of detection of troubles or anomalous processes in the engine's combustion.