The EMC E3 is a 2,000 horsepower (1,500 kW), A1A-A1A passenger train locomotive that was manufactured by Electro-Motive Corporation of La Grange, Illinois. The EMC demonstrator #822 was released from La Grange for test on September 12, 1938. The cab version, or E3A, was manufactured from September 1938 to June 1940, and 17 were produced. The booster version, or E3B, was manufactured in March 1939 and September 1939, and 2 were produced. The 2,000 hp (1,500 kW) was achieved by putting two 1,000 horsepower (750 kW), 12-cylinder, model 567 engines in the engine compartment. Each engine drove its own electrical generator to power the traction motors. The E3 was the fourth model in a long line of passenger diesels of similar design known as EMD E-units.
Compared with passenger locomotives made later by EMD, the noses of the E3, E4, E5, and E6 cab units had pronounced slants when viewed from the side. Therefore, these four models have been nicknamed "slant nose" units. Later E models had the "bulldog nose" of the F series. E3 demonstrator 822 was built with a nose identical to earlier EA and E1A units, but later locomotives in the series featured an elevated headlamp mounted in a nacelle, distinct from the flush profile mounting of the earlier units. 822 was modified in a similar fashion prior to delivery to the Kansas City Southern
The E3 introduced a 12-cylinder version of the 567 series engine, two were used, developing a total of 2,000 hp at 800 rpm. Earlier E models had used twin Winton 201As, but that engine was ill-suited to railroad use and was unreliable. The 567 was designed specifically for railroad locomotives, a supercharged 2 stroke 45 degree V type with 567 cubic inches (9,290 cm3; 9.29 L) displacement per cylinder which remained in production until 1966. Two D.C. generators, one per engine, provide power to four motors, two on each truck, in an A1A-A1A arrangement. This truck design was used on all E units and on MP 7100, CB&Q 9908, and Rock Island EB6 power cars. EMC/EMD has built all of its major components since 1939.
Only one E3 survives today. It was formerly owned by the late Glen Monhart, and operated on excursions in Wisconsin. Today, it is owned by the North Carolina Dept. of Transportation Rail Division, and is on long term loan to the North Carolina Transportation Museum, in Spencer, North Carolina. It is ex-Atlantic Coast Line Railroad E3A #501. It is stored in operating condition, and will be run occasionally. In January 2013, NCDOT transferred ownership of the engine to the NC Department of Cultural Resources, Spencer Shops parent organization.