O.S. Engine 91RZ-H DH Rear Exhaust Engine for Scale Helicopters  [OSMG1979]

Engineered Fit and Power: O.S. Engine 91RZ-H DH

Scale helicopter fanciers looking for a clean install and dependable output will value the O.S. Engine 91RZ-H DH. The rear-exhaust configuration helps preserve the canopy profile while delivering usable thrust for precise flight.

Performance Numbers and Internal Refinements

The 91RZ-H DH features a 0.91 cu in displacement and a rated output of 3.3 hp at 15,000 rpm, with a practical RPM spread from 2,000 to 16,000. Improved intake porting and a redesigned crankcase enhance reliability and make throttle transitions more consistent.

Selectable Head Designs for Cooling and Fit

Choose between a larger blue anodized head that improves heat dispersion and a compact squared die-cast head for cramped engine bays. This lets builders trade off cooling capacity against installation space.

Preserving Scale Lines with Rear-Exhaust Layout

The rear-exhaust layout tucks the muffler and piping out of sight, helping to maintain authentic scale lines and reduce visible exhaust clutter on finely detailed models.

The O.S. Engine 91RZ-H DH suits modellers who need a compact, tuneable engine that keeps a model's scale silhouette intact without sacrificing controllable power.