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Cylinder pressure analysis in internal combustion engines involves measuring very large quantities of data, typically 2 Mbytes per test point. Derived results, such as peak cylinder pressure, IMEP and burn angles can be calculated either in real-time or by post-processing of the pressure data and the need for long term saving of the raw data after processing is then optional. Despite the many advantages of retaining the raw data, this is often not done because of the necessity for large capacity storage systems and the time required to transfer the large files across networks. The ideal situation would be to save the derived results and statistical parameters plus the raw pressure data in a much more efficient format which offers substantially smaller data files without significant loss of accuracy and functionality.

A major problem with making accurate cylinder pressure measurements using piezoelectric pressure transducers in IC engines is thermal shock. This affects most derived parameters although the greatest error is in the indicated mean effective pressure (IMEP), which can be affected by over 10%. In this paper, thermal shock has been quantified for a wide range of engine conditions. Thermal shock was found to be most significant at low engine speeds, high loads and advanced ignition timings. A good correlation between thermal shock and peak pressure has been established for Kistler 6123 and 6125 transducers when dealing with cycle averaged data. This resulted in the development of a numerical thermal shock correction routine which was used for all subsequent data processing. Use of this improved analysis software demonstrated that the error in the calculated IMEP was significantly improved for the Ford Zetec engine tested.