The EMD BL20-2 is a diesel-electric locomotive that was introduced in order for EMD to gain entry to the rebuild market for the second time.
Nearly a decade after production of the GP15-1 ceased, EMD revived the BL series in an attempt to crack the rebuild market and compete with GE's Super 7 series.
All three BL20-2 demonstrators, road numbers 120-122, were built on the 56-foot-2-inch (17.12 m) frames of ex-Burlington Northern GP9s of Chicago, Burlington & Quincy, Northern Pacific and Spokane, Portland & Seattle heritage. All three demonstrators were outshopped from La Grange in mid-1992. They bore no resemblance to the pre-GP series EMD BL1 and BL2 models of the late 1940s. Neither did they resemble GP9s, at least not from the frame up. On the inside, the unit married the technology of two generations, with a rebuilt 16-567C engine crankcase with 645 power assemblies. An EMD turbocharger was applied in place of the normal Roots blower, but it did not have a clutch assembly. It could not free wheel as a normal EMD turbocharger does. It was coupled to the engine gear train over the entire throttle range. The combination of the "turbo blower", 645 power assemblies and an increase in engine speed to 900 rpm boosted the output from 1,750 to 2,000 horsepower (1,300 to 1,490 kW) mated to an AR10 alternator and Dash 2 electrical system. Although the GP9 frame, trucks, traction motors, fans and prime mover were rebuilt and reused, the locomotive received an all-new cab and carbody, basically that of a standard second-generation GP. Still, the unit had an unmistakable appearance, due to the absence of inertial air intakes behind the engineer's side of the cab, and the use of a squared-off dynamic brake assembly similar to that of a GP60.
Competing in one of the toughest fields in the locomotive business, the three BL20-2s demonstrated for two years, but won no orders. They were redeployed to EMD's lease fleet in 1994, and have worked for several shortline railroads since then.