**7. Conclusions**

In this work, experimental and 1D numerical analyses were performed on a twincylinder turbocharged spark ignition engine with the aim to study the effects of cylinderby-cylinder variation on performance, combustion and gaseous emissions.

In a first stage, experimental tests were carried out at different speed/load points and EGR rates. The experiments pointed out the following main results:


In a second step, a 1D engine model was realized in a commercial code and integrated with "users" in-cylinder sub-models to refine the description of turbulence, combustion, heat transfer and emissions.

Numerical study has pointed out the following main outcomes:


The wide numerical/experimental investigation of the influence of cylinder-by-cylinder variation on performance and emissions of a SI engine represents the novel contribution of this work compared to the existing literature analyses. The proposed modeling approach has the relevant benefit of a favorable compromise between the results accuracy and computational cost. It can be proficiently adopted to support the control and the design of a spark ignition engine for cylinder-by-cylinder variability suppression with the aim of improving performance and emissions.

**Author Contributions:** Conceptualization, methodology and formal analysis, L.M., C.T., L.T., F.B., G.V.; software and validation, L.T.; experimental setup, investigation, data acquisition and data curation, L.M., C.T. and L.T.; writing—original draft preparation, L.T., C.T. and L.M.; writing—review and editing, visualization and supervision, L.T., C.T., L.M., F.B. and G.V. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Not applicable.

**Acknowledgments:** The authors thanks Alfredo Mazzei for the support to the experimental campaign.

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