SD50 Diesel Locomotive

Prototype Information

The EMD SD50 hit the market in 1981 as EMD’s answer to the growing horsepower race. Its 16-cylinder 645F3B engine produced 3,500 horsepower, giving it more muscle than the SD40-2. EMD stretched the frame for larger radiators, added updated electronics, and promoted the SD50 as the future of heavy freight power.

Conrail, Chessie System, Norfolk Southern, and Union Pacific all bought fleets, with nearly 430 built between 1981 and 1985. But the new 645F engine proved troublesome, and reliability issues quickly hurt the model’s reputation. Many railroads cut back on orders and shifted business to GE, which was gaining ground fast.

Even with its flaws, the SD50 stayed in service for decades. Railroads rebuilt or derated many into SD40-3s, keeping the frames and trucks working long after the original design lost favor. A number of SD50s still run today, reminders of EMD’s missteps in the 1980s horsepower race.