O.S. Engine OSMG1975 91HZ Precision F3C Helicopter Motor  [OSMG1975]

Next-Level Helicopter Drive: O.S. Engine 91HZ

The O.S. Engine 91HZ is a focused contest engine that benefits from pilot feedback to refine handling and heat management. Evolving from the 91SZ-H, it offers tweaks aimed at keeping power delivery consistent during complex routines.

Cooled Design for Stable Running

Engineers gave the unit a narrow heat sink head so it tucks into common cooling shrouds without fuss. Heat is pulled away by both the head and a crankcase sink, helping the engine stay on point through long practice sessions and flights.

Carburetion and On-Task Adjustment

The fitted 61B carburetor improves repeatability when dialing in mixtures. An insulating ring limits heat transfer from the crankcase to the carb, while multiple O-rings reduce unwanted air ingress. The in-flight needle arm lets pilots trim mixture without landing.

The 91HZ suits competitors and keen hobbyists aiming for consistent thermal performance and straightforward in-flight tweaking to keep the helicopter responsive during routines.