Specifications include, but are not limited to: The Proposer shall select two Tier 4 final off-road diesel engines with similar power ratings. One engine will be certified and equipped with the SCR system only, and the other engine will be certified and equipped with a combined DPF and SCR system. In addition to funding available through this solicitation, the proposer is encouraged to contact equipment, engine, and aftertreatment manufacturers and associations for partnership or commitments to provide funding or in-kind support for this project. Proposers who rely on financial or inkind support from partners must include in their proposal binding commitment from all co-funding and in-kind partners. The Proposer shall test both engines on an engine dynamometer over the same test cycles, and measure the emission rates of criteria pollutants including NOx, PM, NMHC, and CO, and non-criteria pollutants such as carbon dioxide (CO2), individual volatile organic compounds (VOCs), metals, particle number (PN), and polycyclic aromatic hydrocarbons (PAHs). In addition, the proposer shall be capable to identify and recommend potential engine and aftertreatment control strategies to maximize emission reductions over the test cycles using a numerical model.