THE RARE AND ELUSIVE GENERAL MOTORS 1-71

by Diesel World Automotive Magazine

Being the massive online diesel engine magazine that we are, we bring you the old and the new. So, this time around were looking at the General Motors 71 Series two-stroke diesels. These power plants may have done more to bring America into the diesel age than any other engine.

Conception of the 71 Series engines began in 1934, when GM decided to expand the product line, update the Winton ideas and implement them in a line of smaller diesels to be sold through a new outfit called the GM Diesel Division (later known as Detroit Diesel). By 1937, GM Diesel had the bones of a new engine design. By March of 1938, they had the line tooled up, the testing done, and production began in April on two-stroke diesels in one, three, four and six-cylinder configurations.

Called the 71 Series, the “71” represented the cubic inch displacement of one cylinder. The individual engine designations used the 71 preceded by the number of cylinders, so a four-cylinder 71 Series was called the 4-71, a six was the 6-71, and so on. This became the nomenclature convention for the entire GM lineup, and it continued for decades. These engines continued in mainline production until 1995 and millions are still in service. They are still in limited production today for certain military markets in which they are the preferred power plant.

The 71 Series shared many parts and came in a wide variety of configurations. Today we might call it a modular design. The first flagship engine was the 6-71. It powered everything from generators to tanks, ships, busses and more.

The 1-71 came in three known configurations: a generator model (with a “G” suffix, e.g. 1-71G), a power take-off model (“P” suffix) and a marine (“M” suffix). There might have been a fourth version built for pumps, but the details have proven elusive and the designation for it is not known. The 1-71 was generally rated at 15 continuous horsepower at 1,200 rpm and 87 lb-ft at 800 rpm At rated continuous power, the 1-71 used about one gallon of diesel fuel per hour.

Because it was in production for such a short time and so few engines were built, the production story on the 1-71 is far from complete. The best available information states the 1-71 started production in April of 1938 with the 3-71, 4-71 and 6-71 (the 2-71 came in 1940) but no final production date has been found. The best educated theories are that the 1-71 production ended as early as 1940. It’s known that engines were installed later, possibly from unsold stock, and the most reliable sources list less than 1,000 engines built.

The reason for discontinuing the 1-71 is another elusive fact. Collectors and historians speculate that because it was one of many such small engines on the market, and possibly overpriced in that market, it didn’t generate as much enthusiasm as the rest of the 71 Series. The 2-71 debuted in 1940 and was possibly deemed a better product to represent the bottom of the lineup. Once the war ended, it’s clear the GM Diesel marketing team did not see a need to bring the 1-71 back.

As with all 71 Series diesels, tales of longevity are often told. One involves a 1-71G that was used at the weather station on top of Mount Washington, New Hampshire (home of the worst winter weather in North America), from 1939 to 1986 and was almost never shut down. That engine is now in a private collection and is still running. That’s longevity!

Source:- @ https://www.dieselworldmag.com/