The DeLong 29 diesel was one of a surprising number of still-born American diesels which reached the prototype stage during the early post-WW2 period prior to Ray Arden's introduction of the commercial glow-plug in late 1947. Designed by Everett M. DeLong, a handful of prototypes were made and tested prior to the engine's abandonment by its manufacturers, Super Motors Inc. of Cleveland, Ohio, more or less immediately following the late 1947 appearance of the glow-plug. As a result, the engine never entered series production.
This is a great pity because, as present-day tests have shown, the Delong 29 diesel was actually a very good engine by the standards of its day, and one with a considerable amount of development potential. Only two surviving original prototypes have been reported to date, while a small handful of replicas were made beginning in 2000 by the members of Motor Boys International. Consequently the engine is mega-rare today.
Full details of the DeLong 29 diesel story may be found in a separate article on this web-site.