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O.S. 91HZ-R 3C Speed Red 61F Heli Engine

Model No.: OS-18641

Price: US$489.00

Availability: This product is currently SOLD OUT
Order quantity:
Out of Stock


O.S. Speed 91HZ-R 3C Red Ringed w/ Pump, 61F Crab 2-Stroke Engine + O.S. 90 PowerBoost Pipe for F3C Helicopter NEW!

Following the popularity of the 91HZ-R with On-Demand Regulator, O.S. has now taken high-performance, high-speed helicopter engines to the next stage of evolution. Introducing the 91HZ-R Speed Engines - based on the 91HZ-R, factory-tuned at the O.S./Japan facilities and guaranteed to blow you away!

The 3C version is designed expressly for F3C competition with its controlled, precise maneuvers in mind. For pilots who prefer aggressive, stick-bashing 3D flight competition, O.S. offers a 3D version.

Features found in both versions include:

  • Lightweight, machined heatsink head
  • Big-bore carburetors best-suited for the intended use (F3C or 3D)
  • Best precision advanced exhaust cylinder timing (for F3C or 3D)
  • Newly designed combustion chambers, shaped to match the big bore carburetors and advanced exhaust cylinder timing
  • Lightweight, forged steel crankshaft counter weight to lower vibration for higher speeds
  • Improved back plate shape, to accommodate Futaba's BPS-1 RPM Sensor and increase primary pressure for greater stability


91HZ-R 3C Speed Engine Red

Achieve faster flight speeds and improved hovering stability. In order to get the greatest power from this engine, the carburetor intake bore is maximized to 11.6mm. To match the large bore intake, the cylinder exhaust timing has been advanced to 170 degrees. This all contributes to extreme horsepower with high speeds for stable hovering.

Package Included:
O.S. Speed 91 HZ-R 3C Helicopter Engine
Instruction Manual

Stock Numbers:

      OSMG1980 91HZ-R 3C Speed Red 61F
Displacement: 0.91 cu in (14.9 cc)
Bore: 1.09 in (27.7 mm)
Stroke: 0.98 in (24.8 mm)
Output: 3.6 hp @ 15500 rpm
Practical RPM Range: 2,000-16,500
Weight (w/o Muffler): 21.2 oz (603 g)


Code No. 18641

This product was added to our catalog on Wednesday, 04. May 2011.
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