Fred A. Thaheld was the principal in Diesel Power, Inc., a division of Shafter Tool Works, of Brea, California. Thaheld had been Vice President and Chief Engineer of Guiberson Diesel Engine Company of Dallas, Texas from about 1932, and directed their aircraft diesel-engine development. Guiberson built three different 9-cylinder radial diesel engines for aircraft. The first of these, the A-980, received TC = 79 on 2/17/32. The horizontally-opposed diesel Thaheld engine is described here.
O-290 (Diesel) -- {4.875 / 3.875 / 289.3} / {123.8 / 98.4 / 4741}
4cyl; Thaheld O-290 Diesel; 100-120hp@2400rpm; 1945-1947; Wt = 235#; TC = none.
The difference between the 100 and 120 horsepower versions was in the fuel injection system. Bench testing for 700 hours was reported.
J47; Skyways (including Air News) magazine for 12/46 (with photo of engine); The Engineering Index for 1946 refers to publication of information under the Shafter name in Oil Engine, Vol.13, No.154, February 1946, p.285 - Compiler has not seen this article.
Applications: (US) Stinson Model 10 Voyager; possibly others.