Walter Minor

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 hp to 160 hp.[1] After Walter concentrated on the turbine powerplants only, the production of piston engines has been transferred to the Avia company that further developed the family, bringing fuel injection, as the Avia M-137 and M-337. Nowadays the smallest of the family, the four-cylinder carburetted Minor, is produced by a small company in the Czech Republic, while the M337 was available from the LOM Prague.

Preserved Walter Minor 6-III
Type Inline piston engine
National origin Czechoslovakia
Manufacturer Walter Aircraft Engines
First run 1929


4 Cylinder

Minor 4-I
Minor 4-II
Minor 4-III
Minor 4-IIIS
A 4-III fitted with a crankshaft driven supercharger.
Minor M 332 (4 cyl.)

6 Cylinder

Minor 6-I
Minor 6-II
Minor 6-III
Minor 6-IIIS
A 6-III fitted with a crankshaft driven supercharger.
Minor M 337 (6 cyl.)


Minor Sc.
Minor 12 1-MR


Specifications (Minor 4-cylinder)

Data from: [3]

General characteristics

  • Type: 4-cylinder inverted inline air-cooled
  • Bore: 105 mm (4.14 in)
  • Stroke: 115 mm (4.53 in)
  • Displacement: 4 L (244 cu in)
  • Length: 1,119 mm (44.09 in)
  • Width: 440 mm (17.32 in)
  • Height: 630 mm (24.80 in)
  • Dry weight: 93 kg (205 lb)


  • Valvetrain: 1 inlet and 1 exhaust valve per cylinder
  • Fuel system: 1 Claudel carburetor
  • Fuel type: 68 octane
  • Cooling system: Air-cooled


See also

Comparable engines

Related lists


  1. Gunston 1989, p.174.
  2. "National Technical Museum, Prague". Retrieved 8 July 2013.
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