The Batzloff Triumph was the name applied to a pair of successive .604 cuin. (9.90 cc) racing engines designed by William J. "Bill" Batzloff (1912-1966) of San Diego, California, USA in 1941 and 1946 respectively. Despite the use of the same name for both models, they were widely divergent designs.
Both engines were mainly sold as sets of castings and plans, although Bill Batzloff did make and sell a few complete examples of each model. The engines' very limited production was very much a sideline for Batzloff, whose primary employment was as a diver and lab technician at the Scripps Institute of Oceanography in San Diego. Only perhaps a few dozen examples were produced either as casting sets or as complete engines before America's December 1941 entry into WW2 terminated the project.
The 1941 Triumph was a development of the contemporary .604 cuin. design by Bill Batzloff's good friend and fellow competitor Ira Hassad, which was a dominant force in model rail-guided car racing at the time. It was primarily intended for use in model race cars. Although at first sight it appeared to be in effect a "back to front" version of the Hassad model, the 1941 Triumph was actually a completely distinct design. It incorporated a well-developed rear drum valve as opposed to the Hassad's crankshaft front rotary valve (FRV) arrangement. It also incorporated significant changes to the bypass system as well as a single ball-race crankshaft in place of the Hassad's bronze bushing.
After the war, Batzloff first designed the famous FRV Hassad .61 Custom for his friend Ira Hassad, whose interest in model engine design was waning at that time. Batzloff then went his own way, developing a totally different version of the Triumph incorporating disc rear rotary valve (RRV) induction along with cross-flow loop scavenging. In this, he was acknowledging the influence of the very successful Hornet 60 and McCoy 60 designs which were then coming to dominate the competition scene in America.
Both versions of the Batzloff Triumph are briefly covered in my article about the life and work of Ira Hassad. An in-depth article about Bill Batzloff and his engines will appear here in due course.