GPU Surplus (US)

"GPU Surplus" is simply a name selected by the Compiler to include the Ground Power Units (GPU) that were used for many years by the US Military Services for various purposes. These Units were powered by either a single-cylinder or two- or four-cylinder horizontally-opposed four-stroke cycle gasoline engines. These GPU's have been declared surplus in recent years by a Military requirement to eliminate aviation gasoline as a necessary fuel at their bases and facilities worldwide. Most GPU equipment now is powered by diesel or gas-turbine engines. It should be mentioned that the first surplus GPU engines were those designed and built by Lycoming during WWII based on the Lycoming O-290. These engines are discussed on the Compiler's Lycoming Part 1 Webpage.

Design of the "GPU Surplus" engines is attributed to Teledyne Continental Motors (KP8/03, 11/03). The engines were built by Hercules, Willys, and Bowen-McLaughlin as well as by TCM (KP11/03). There were at least two families of engines built with individual cylinders of approximately 8 cu.in. and 21 cu.in. displacement, respectively. The engine models that have the most appeal for ultralight homebuilders are the 4A084 four-cylinder and the related 2A042 two-cylinder engines which are described below. Another engine of interest is the 4A032, for which the Compiler has little information but it is listed below. Interests in these particular models has arisen because they are in the displacement, horsepower, and weight range of the early, small, VW conversions, say the four-cylinder VW "1300cc" and VW "1500cc" and some of the smaller 1/2 VW engines, all of which are described on the VW Webpage of this Compilation. There are four registered Groups on Yahoo that discuss these engines, among others. One is the Surplus Engines Group, which began in February 2002 and for which a reader must register to access the postings. The second is the 4A084 Experimenters Group, which began in July 2005 and may be accessed by the public. The third is the 2A042 Group, which began in August 2003 and requires registration. The fourth is the 4A032 Group, which began in June 2003 and is public. The compiler has read postings on the Public Groups, but has not registered on the others.


O-32 - - {N/A / N/A / 32} / {N/A / N/A / 524}

4cyl; 4A032; 20hp@N/A rpm; 1999-present; Wt = 55#; TC = none.
Single-ignition engine.
KP11/03; Yahoo Groups.
Applications: None found.


O-42 - - {3.0 / 3.0 / 42.4} / {76.2 / 76.2 / 695}

Same bore and stroke as O-84.

2cyl; 2A042; 25hp@N/A rpm; 1999-present; Wt = N/A; TC = none.
Single-ignition engine.
KP11/03; Yahoo Groups.
Applications: None found.


O-84 - - {3.0 / 3.0 / 84.8} / {76.2 / 76.2 / 1390}

Same bore and stroke as O-42.

4cyl; 4A084; N/Ahp@N/A rpm; 1999-present; Wt = N/A; TC = none.
Single-ignition engine.
KP8/03, 11/03; SP(then Experimenter)9/99; Yahoo Groups.
Applications: (US) Sky Raider (built by Warren Scruggs); TEAM Mini-Max (built by Ed Burt).


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Updated 8/11/07