The first Polish-designed engine to be series-produced after World War II.
In the early 1950s, the Polish military aviation placed an order with the aviation industry for a new training aircraft, the development of which was undertaken by Tadeusz Soltyk’s team. The Soviet engines available at the time did not meet the technical requirements for the powerplant intended for this type of aircraft.
A team led by engineer Wiktor Narkiewicz designed an engine that proved to be a very successful powerplant, meeting all the requirements. It was a development of the earlier WN-2 engine. The design was based on proven solutions from Polish pre-war designs. The engine had no supercharger or reduction gear and was started using compressed air.
A total of 329 engines were produced at WSK Kalisz. Production ended in 1970. It was used in the WSK TS-8 Bies aircraft and in prototypes of the WSK MD-12 passenger aircraft.
| Configuration | 7-cylinder radial |
| Cooling | air |
| Compression ratio | 6.2 |
| Displacement | 13.4 l |
| Weight | 240 kg |
| Maximum power | 320 hp at 2350 rpm |
| Rated power | 283 hp at 2250 rpm |
