H-Engine Development of the H-engine was announced in 1994 as a railway locomotive specific engine - the design was influenced by the transition to AC traction motors, which had increased adhesion and tractive effort characteristics, allowing an increase in usable power to be usefully converted traction - thus the new design was to have available for traction - a 6000 hp locomotive design would allow one to replace two of the very common 3000 hp
SD40-2 locomotives. The 16-265H remains the most powerful diesel engine ever produced by EMD.
J-Engine To meet
EPA Tier 4 emission standards for nitrogen oxides (
NOx), manufacturers rely on one of two methods:
exhaust gas recirculation (EGR), where exhaust gases are cooled and recirculated back through the combustion cycle, or
selective catalytic reduction (SCR) using
urea-based
diesel exhaust fluid, which converts NOx in the catalytic converter to elemental nitrogen and water. Although EGR requires a diesel particulate filter, it is the preferred solution for
Class I operators, as SCR adds
another consumable with handling and storage problems by maintenance personnel. The four-stroke engine design was re-introduced in the mid-2010s to meet Tier 4 without using SCR. Although EMD had experimented with modifying the 710 to meet Tier 4, the prototype proved to be too heavy and inefficient to be practical. Testing of the new locomotives began in the Spring of 2016. The first two units of a 65 unit order for the new locomotive were delivered to Union Pacific in December 2016. The block designation was changed to J to reflect the changes to the new engine, which included power assembly and block redesigns, as well as the addition of a two-stage turbocharging system consisting of three turbochargers. Other new features are an EGR system to reduce exhaust emissions and double-walled fuel injection to increase safety. == Versions ==