In efforts to develop larger engines for the Oliver Models 2050 and 2150 tractors, the Oliver Corp. found it could use a modified version of a 478 cu in. engine already designed for Army trucks. This paper describes the resulting new 118 and 131 hp tractor engines that emerged from compromises with the military engine. One of the most compatible features of the engine was its M.A.N. combustion system. Included in the Appendices are results of tests made on the tractors by the University of Nebraska Agricultural Experiment Station at Lincoln.