See General Motors for main information and the list of engines.

This well-known American automotive company saw its engines adapted for amateur construction, in innumerable examples.

General Motors logo

-Besides the well-known contribution during WWII, it made a 4-cylinder, radial engine known as the "U-type". The cylinders were arranged radially. It was the R-250-1 and -3.

-The R-250-3 was supercharged. Their military version was the X-250D, designed in 1943 by GM's Research Laboratory. They were tested on Cessna aircraft.

-They were liquid-cooled, 2-stroke engines. The maximum power was 200 hp at 2,275 rpm, with gearbox. The dry weight was 275 lbs.

-As we have seen, GM, as a large industrial organization, brings together Allison Division and Detroit Diesel Allison (now Rolls-Royce).

-The adaptation of automobile engines is substantial although it can be said that all have been carried out experimentally.

-Pinto and Chevrolet engines were installed on small aircraft, and in the illustration below we can see a Corvair 6-cylinder with a displacement of 2,687 cc, giving 115 HP at 4,400 rpm, installed on a small plane.

“Corvair on board”

-George Morse was an example of these GM-engine adaptations, with his Auto Aviation Olds (from Oldsmobile) that boosted his Skybolt and Prowler planes. The same for Steve Williams and his Tailwind.

“GM 215”

-The Pontiac, Oldsmobile and Buick 215 hp engines with "Jetfire" turbochargers and aluminum blocks, were highly appreciated.

From Appendix 6: During the First World War, in 1918, Buick (GM = Cadillac + Buick) presented the water-cooled L-12A Liberty.

-The engine in the below photograph (NASM File) became known as the Model A Buick and was mounted on the Fokker T-2.

“Liberty L-12A made by Buick” (PiP)

-We located a General Motors radial engine intended for the Pontiac X-4 experimental car. This engine is mentioned as model X-250 in the main text.

-In the documentation where the information was obtained it is said that the X-4 car engine is a derivative of the X-259 engine in turn derived from the X-250. The X-259 is considered the grandfather of the X-4 engine, so the X-250 would be a great-grandfather.

“The Pontiac X-4 with radial engine”

“X-4 engine with rigid rods”

-As we see, connecting-rod system and pistons act as shuttles like in the Bourke engines.

-GM developed this engine jointly with Williams International (see) to be used as APU, auxiliary generator and possibly for cruise missiles. It is proclaimed for high fuel efficiency.

“GM-Williams small turbine”

From appendix 13: Adaptations of the powerful General Motors car engines continue to appear.

-A new proof is the 620 hp Bigblock engine for the agricultural "Airtractor" aircraft. The conversion is done by EPI Inc.

“Bigblock on a test bench”

-From the GM "Kuva" vehicle there is a conversion of its LS-3 block for a Cessna C-172 aircraft.

“Two photographs of the Kuva LS-3 on a Cessna C-172”

"Curious LS-1 engine with double exhaust pipes"

-The double exhaust pipes can be destined for a WWII fighter jet replica.

-Below we show another version of a GM block LS-1 engine for another application.

“LS-1 with a Geared Drives gearbox”

“LS-1 Adapted with Rotator gearbox”

“Like the V8, V6 engines are used as well”