The Walter Minor is a family of four- and six-cylinder inverted inline air-cooled engines, developed under auspices of ing. Šimůnek and used on light aircraft. First produced in 1929, the Minor engines' family has an advanced design for the period and sports steel cylinders, aluminum heads and overhead valves, with identical bore and stroke of 105 mm (4.1 in) and 115 mm (4.5 in), respectively. Typical power ratings varied from 105 to 160 hp (78 to 119 kW).