Siemens-Halske no longer had any competitive engines for the larger end of the market, and to address this they negotiated a license in 1929 to produce the 9-cylinder Bristol Jupiter IV. Minor changes for the German market led to the Sh.20 and Sh.21. Following the evolution of their smaller Sh.14's, the engine was then bored out to produce the 900 hp design, the Sh.22. In 1933 new engine naming was introduced by the RLM, and this design became the Sh.322, when Siemens was given the 300-block of numbers. The Sh.322 design had reliability problems and never became popular.