This dataset contains experimentally validated steady-state operating data for a fumigation-assisted compression ignition engine operating at 1500 rpm. The dataset includes raw experimental measurements, processed surrogate-modeling inputs, derived energy-based features, and multi-objective optimization results. The dataset supports energy-oriented surrogate modeling and emission-constrained optimization for improving brake thermal efficiency while limiting nitrogen oxide emissions. Files included:- Raw experimental data- Processed modeling dataset- Variable definition sheet- Optimization summary- README documentation