As ammonia (NH3) is the best hydrogen carrier for safety and efficiency, transportation engines have been proposed using ammonia. NH3 may be used as a single combustion fuel for an internal combustion engine. However, as NH3 is a difficult fuel for what concern's combustion, faster and more complete combustions may be achieved by working dual fuel. The most promising alternatives are offered by using either diesel injection ignition plus port/direct injection of the NH3, or jet ignition of a gasoline-like fuel (gasoline, CH4, C3H8, H-2) plus port/direct injection of the NH3. The opportunity of diesel injection ignition plus direct injection of NH3 is considered here. The simulations show the prospect to achieve Diesel-like power densities and efficiencies, and load control by quantity of fuel injected. Critical component for prototyping is the high pressure fuel injection systems specifically developed for NH3. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.