EPA Tier 2 locomotive exhaust emission levels for U.S. locomotives present significant challenges in the reduction of NOx and particulate emissions compared to Tier 0 and 1 levels. Further tuning of legacy engines would have resulted in large losses in fuel economy to achieve NOx levels and provide for deterioration of PM, HC and smoke. For these reasons, GE Transportation Systems responded to the Tier 2 requirements with a new engine that will meet the emissions levels with margin against deterioration and with improvement in fuel consumption. This optimized balance of emissions and economy is achieved without the additional complexity of aftertreatment devices. The first engine of the GEVO family will be introduced in the Evolution Series locomotive in 2005. The performance development of the engine involved combustion modeling, system modeling and optimization. The fuel injection system was statistically designed to provide highly efficient and robust operation. The turbocharger design used advanced aerodynamic and structural modeling to achieve high levels of efficiency and safety. The reliability of each system and component was evaluated using a rigorous Design for Reliability (DFR) process followed by extensive locomotive field testing.