OS 91 HZ "Pumped" Helicopter Engine

Designed primarily for the 3D flight and dramatic aerobatic manouevres.. Compared to the old 'Hyper' the new 91HZ-PS offers improved hovering stability as well as power at high speed to meet the further sophisticated 3D competition manouevres.

A new design piston and crankshaft reduces vibration to provide further, stable torque over the entire RPM range. The rectangular heatsink head is completely included in the cooling shroud for better cooling. The black alumite finish with O.S. and 91HZ-PS logo impart a distinctive image.

A Thermo insulator is installed on the carburetor mounting spigot and helps shut out engine heat to the carburettor, which in turn ensures a stable fuel/air mixture

The 91HZ-PS is equipped with a new, bigger capacity PD-08 pump and matched 61B-P carburettor plus integral regulator, which assures a consistent fuel supply irrespective of violent changes in model attitude.

Combined with O.S. pump system, internal parts improvements same as the 91HZ contribute to stable power output and smoother higher engine performance.

Specification

Displacement: 0.91 cu in (15 cc)
Bore: 1.091 in (27.7 mm)
Stroke: 0.976 in (24.8 mm)
Output: 3.5 ps @ 15,000 rpm
Practical rpm range: 2,000–16,000
Weight w/o muffler: 22.39 oz (635 g)

Includes: OS #8 glow plug