In the horsepower race between GE and EMD, the last model built by GE was the AC6000CW. Its basis was the 7HDL-16 engine developed with the help of Deutz that delivered 6,250 hp, but was set at 6,000 hp in the locomotive. It didn't take long until it was found out that the engine had reliability issues. So from 186 locomotives ordered by Union Pacific, 106 were built with the 4,400 hp 7FDL-16, but with the stronger frames and more powerful generators and traction motors needed for the more powerful engine. They were called “Convertibles” and intended to be converted to the more powerful engine as soon as the reliability problems were solved.
The other big customer was CSX with 117. BHP Billiton in Australia got eight. In 2001, all these eight set a world record by hauling a coal train of 682 tonnes that weighed 99.734 tonnes. All these had been replaced by EMD SD70ACE by 2014. Union Pacific later re-engined their 6,000 hp locomotives with 7FDL-16 rated at 4,400 hp. CSX also replaced the engine of their first three AC6000CW with the 7FDL-16, but all others got the more modern GEVO-16 with 4,600 hp. Nevertheless, most have been already retired.
