**5. Conclusions**

This paper has proposed an approach on engine combustion fitting using the Seiliger process model, in which the in-cylinder pressure data measured from the engine test bed is applied for the experimental investigation. The combustion fitting results of each cylinder and average four-cylinder pressure signals obtaining the Seiliger parameters are discussed to verify that the combustion fitting is suitable to parameterize the engine combustion process and then for investigating the tendency of Seiliger parameters along with engine operating conditions. The conclusions can be drawn as follows:


The combustion fitting approach investigated in this paper is applied in diesel engines, but it can be also used in the substitute fueled engine due to the first principle used in the research. The method provides a way to develop a new engine combustion model with fast response when used in the integration system simulations.

**Author Contributions:** Conceptualization, Y.D.; Data curation, C.S.; Formal analysis, J.L.; Investigation, C.S.; Methodology, Y.D. and J.L.; Project administration, Y.D.; Software, Y.D.; Validation, Y.D. and C.S.; Visualization, C.S.; Writing—original draft, Y.D. and J.L.; Writing—review & editing, C.S.

**Funding:** This research was funded by 'International Science & Technology Cooperation Program of China', 2014DFA71700; Marine Low-Speed Engine Project-Phase I.

**Conflicts of Interest:** The authors declare no conflict of interest.
