O.S. Engine OSMG1975 91HZ Competition Helicopter Engine  [OSMG1975]

Refined Competition Power from O.S. Engine 91HZ

The O.S. Engine 91HZ brings focused engineering to F3C helicopter powerplants, developed with input from top pilots to balance control and endurance. Based on lessons from the 91SZ-H, this unit adds practical refinements for contest flying and tight installation spaces.

Built for Accurate Control and Cooling

This engine is tailored for pilots who need steady, predictable throttle response. A narrow heat sink head lets the unit sit neatly inside common cooling shrouds, while dual heat sinks on the head and crankcase move heat away efficiently to preserve performance during long sequences.

Tuning Stability and In-Flight Adjustment

With the supplied 61B carburetor, the 91HZ improves tuning repeatability. An insulating ring reduces crankcase heat transfer to the carb, and multiple O-ring seals cut down on air leaks for cleaner idle and midrange. The in-flight needle arm lets you fine tune mixture on demand.

For competition pilots seeking consistent thermal control and fine tuning, the O.S. Engine 91HZ offers a compact, serviceable package that fits many contest helis and supports precise throttle management.