GT-POWER provides a comprehensive combustion and emissions simulation environment that supports every stage of engine development, from concept evaluation through calibration and validation. Predictive combustion models cover modern engine architectures including direct injection diesel, spark ignition, dual-fuel, pre-chamber jet ignition, and HCCI, while supporting burn rate profiles derived from cylinder pressure analysis, Wiebe functions, or neural networks. Built-in emissions prediction calculates 13 combustion products using equilibrium chemistry, with detailed kinetics and dedicated models for NOx, HC, CO, and soot. The Advanced Combustion Toolset adds a high-speed chemical kinetics solver for knock prediction, burned zone emissions, and exhaust oxidation analysis. Additional flame speed models for hydrogen, ammonia, and methanol support next-generation and alternative fuel engine development.