The MPI MP20B is a diesel-electric locomotive designed and built by MotivePower in Boise, Idaho. Specifications It has a MTU-Detroit Diesel 12V4000 engine. It weighs approximately 277,000 lb and is 59 ft 2 in long. It has a maximum speed of . It also includes a B-B wheel arrangement and an optional dynamic brake. It includes a continuous tractive effort of and a starting tractive effort of . Union Pacific MP20Bs were powered by a Caterpillar 3516C. Owners References B-B locomotives Diesel-electric locomotives of the United States EPA Tier 2-compliant locomotives of the United States MPI locomotives Railway locomotives introduced in 2007 Standard gauge locomotives of the United States