O.S. Engine 91RZ-H DH High-Performance Rear Exhaust Motor for Scale Heli  [OSMG1979]

Compact Power Package: O.S. Engine 91RZ-H DH

Serious scale helicopter pilots will find the O.S. Engine 91RZ-H DH blends compact packaging with tuned performance. The rear-exhaust arrangement helps keep exhaust components concealed for a true-to-scale look.

Key Performance Figures and Engineering

With a displacement of 0.91 cu in and a peak output of 3.3 hp at 15,000 rpm, the 91RZ-H DH operates effectively from 2,000 to 16,000 RPM. Revised intake porting and a redesigned crankcase improve combustion stability and throttle control under diverse flying loads.

Alternate Heat Sink Heads for Tailored Cooling

The engine ships with two head options: a larger blue anodized head for improved heat dissipation and a compact squared die-cast head for constrained spaces. This allows builders to prioritise cooling or fit as needed.

Installation That Preserves Scale Lines

The rear-exhaust design keeps exhaust outlets out of view and reduces interference with canopy shapes. It is a practical solution where visual authenticity and aerodynamic clean lines are important.

The O.S. Engine 91RZ-H DH is a practical choice for enthusiasts who need a compact, tuneable powerplant that respects scale proportions while providing steady performance.