Experimental activity for a small displacement off road diesel engine development

The goal of this Master thesis is to analyse how the hardware selection and validation phases of the development process of a small displacement off-road brand-new engine are structured. First chapter presents the project from the beginning, introducing market-based design choices, briefly explaining the compression ignition combustion process with subsequent pollutants formation in a diesel engine and emissions regulations in Europe and USA, respectively Stage V and Tier 4 Final. Chapter 2 describes the naturally aspirated engine version features, explaining peculiar characteristics of an IDI diesel engine, with its subsequent architectural distinguishing elements: prechambers and pistons, injection system and a short consideration on TC and TCA versions. Layout of the test bench, control and acquisition instruments and engine physical installation in the cell are the contents of chapter 3. Experimental data collected and consequent hardware selection process for the naturally aspirated engine version are presented in chapter 4: in order to obtain target performances and get a Stage V (or an EPA Tier 4 Final) homologation, tests have been done with the engine running at full load on different injection hardware configurations and on different prechambers configurations. Moreover, also saturation curves and injection timing sweeps proved to be useful in understanding the results. The followed direction has been a trade off in between minimization of both soot and NOx, trying to keep them below regulated limits, without causing excessive performance drops. Finally, a conclusion chapter resumes activities done and results obtained, also making useful advices for this project’s future developments.