The O.S. Type 6 (K6) Ignition Engine is a legendary, highly collectible model airplane engine originally produced by O.S. Engines in 1940. Because originals are incredibly rare, it is most famous in the modeling community for this limited-edition 1986 replica release, which was produced to commemorate the 50th anniversary of the company.
Displacement: 9.35 cc / 0.56 cubic inches
Ignition Type: Spark ignition (utilizing an open “Bunch type” timer assembly)
Construction: All-aluminum sand-cast case with upper and lower parts fastened by two large bolts. It features cast-in beam mounts and a screw-in backplate.
Internal Mechanics: Features a ringless aluminum piston with a baffle, a bushed connecting rod, and a steel crankshaft spinning in a brass bushing.
The 1986 Anniversary Replica To celebrate their 50th year in business, O.S. Engines manufactured a strict single batch of exactly 2,000 replica engines.
Design Philosophy: It is a beautiful, flawless “silver” polished recreation of the 1940 engine. It includes authentic markings, with “OS” stamped on the front case, bypass cover, and one mounting lug, while the unique serial number is stamped on the opposite lug.
Packaging: The replica came packaged with modern wiring diagrams, safety warnings, and running instructions.
Rarity and Collector Value: Because of the tiny production run, the K6 replica is considered an absolute crown jewel for vintage model engine collectors. It is very rarely seen in active RC flight and is instead kept as a display “shelf queen”. When they do appear on the secondary market—such as this one or auctions —New In Box (NIB), examples can fetch premium collector prices.
