Fred A. Thaheld designed a diesel engine that was built by his Diesel Power Inc., the Shafter Tool Works, of California.

-Thaheld had been chief engineer at Guiberson Diesel Engine (see).

-But it was in 1945 that he presented this 100 HP engine (with the possibility of 120 HP).

"The Thaheld-Shafter Boxer"

-It was a four-cylinder, horizontally-opposed engine. With this engine he made a 105-miles flight on a Stinson 110 aircraft in 55 minutes, consuming only 2.5 gallons of diesel fuel.

“Fred next to his engine”

-The weight of this engine was 235 lb but the most notable thing was its high compression ratio, 16:1 at sea level and reduced to 11:1 at cruising speed, as it was not supercharged.

-A 6-cylinder version, derived from this 4-cylinder, was designed, with a power in the region of 175-200 HP.