Cummins Inc. has landed a $47.4 million contract from the National Advanced Mobility Consortium to develop a revolutionary new type of diesel engine for the U.S. Army that promises to be lighter and more efficient than those currently in use.
The Advanced Combat Engine (ACE) project is a joint venture between Cummins and California-based Achates Power, who has designed an opposed-piston engine that works on a two-stroke combustion cycle and eliminates the need for a valvetrain.
There are two pistons in each cylinder that compress the air-fuel mixture between them. The movement of the pistons exposes intake ports at the bottom of their strokes, while a direct fuel injection system adds ads diesel as the piston heads come together. A series of gears connect cranks at the top and bottom of the engine to a common output.
According to Achates, eliminating the head reduces heat loss and improves the thermal efficiency of the engine. Cummins says it is targeting a 21 percent reduction in thermal rejection, along with a 50 percent increase in power density and a 13 percent jump in fuel efficiency compared to engines currently in use.
Apparently the primary engine being benchmarked is the 600 hp Cummins VTA-903T that powers the Bradley Fighting Vehicle and could eventually be replaced by the ACE, which is also destined for the Bradley’s replacement if the project goes well.
Tests of the new engine are scheduled to be conducted by the U.S. Army Tank Automotive Research, Development and Engineering Center (TARDEC) starting in 2019.