The objective of this research was to develop dual-loop exhaust gas recirculation (EGR) split strategies. Model-based control was performed by coupling one-dimensional (1D) cycle simulation with control logic, and the EGR split index (ESI) was developed to investigate split effects on performance and emission. The key control logic concept was to compensate the low pressure (LP) EGR rate. Additionally, ESI, a newly developed index, is a non-dimensional factor expressing the high pressure (HP) and LP portions of the total EGR rate. Using the control model and ESI, the maximum EGR rates were determined under each operating condition, thereby maintaining lean burn combustion and minimizing NOX emission. A multi-objective Pareto method was used with the model-based control to optimize the engine operating parameters and thereby minimize NOX formation and fuel consumption. The control logic applied a step transient analysis based on the optimized parameters. (C) 2016 Elsevier Ltd. All rights reserved.