Early models (EA/EB through E2) used the Winton 201-A engine that had been developed in the early 1930s by the partnership of General Motors and Winton. While this engine represented a breakthrough in power-to-weight ratios and output flexibility for Diesel engines, it was a compromise between marine and locomotive requirements and wasn't well suited to the sustained full throttle operation often needed in railroad service. It was not unusual for heavy repairs to be done "en route" on one engine while the other engine propelled the train at reduced speed. The 201-A engines used in E-units were 900 hp (700 kW) V12s. Experience with the 201-A, which was the first two-stroke Diesel engine in operational use, was invaluable in the development of the next-generation Diesel engine, the EMD 567, a purpose-designed engine that achieved a factor-of-five improvement in piston life for locomotive use.