WP #2001, the first production GP20, leads a special train in 2009. Note the high nose.
An EMD GP20 is a 4-axle diesel-electric locomotive built by General Motors Electro-Motive Division between November 1959 and April 1962. Power was provided by an EMD 567D2 16-cylinder turbocharged engine which generated 2,000 horsepower (1,500 kW). EMD was initially hesitant to turbocharge their 567-series diesel engine, but was spurred on to do so following successful tests made by Union Pacific in the form of their Omaha GP20 units. 260 examples of this locomotive model were built for American railroads.
Units built for the Great Northern Railway were equipped with high short hoods and set up to run long-hood forward. Western Pacific received ten GP20s with high noses and dual cab controls.
While the EMD SD24 with six axles was producing 2,400 horsepower (1,800 kW) with an engine of the same displacement, the four axle GP20 was limited to 2,000 horsepower (1,500 kW) by the capabilities of the traction motors of the time. In appearance the locomotive was similar to a late version GP9 or GP18 but with the two exhaust stacks over the engine replaced by a single stack forward over the exit of the turbocharger, in common with later turbocharged locomotives. An identification detail of the GP20 is the small radiator fan added ahead of the large aft fan.
Current owners of GP20s include the Toledo, Peoria and Western Railway (TP&W) and the New York, Susquehanna and Western Railway (NYSW). The Susquehanna's GP20s numbered 2062, 2064 and 2066 came from the Toledo, Peoria and Western Railway and are ex Santa Fe units. The very first GP20 built, Western Pacific Railroad 2001, is preserved at the Western Pacific Railroad Museum at Portola, CA. Watco companies operates three GP20s #2001-2003. The Alabama & Tennessee River Railroad (ATN) recently acquired GWR 5625. This unit is a former EMD Demonstrator of the same number. Blacklands operates GP20 #2036 which was originally AT&SF #1152. The Georgia Northeastern operates GP20s #316 and 4125. Those units trace back to Great Northern #2016 and Southern Pacific #7205.
- Pinkepank, Jerry A. (1973). The Second Diesel Spotter’s Guide. Milwaukee, WI: Kalmbach Publishing Company. ISBN 0-89024-026-4.