• O.S. Max .91 HZ-PS 3D Competition Helicopter Engine

O.S. introduces the new MAX-91HZ-PS expressly for 3D Helicopter competition. Intended to provide steady and constant power at all times irrespective of violent attitude changes, the new MAX-91HZ-PS is equipped with a newly designed PD-08 pump. The new PD-08 pump now has 25% more capacity to meet the advanced requirements for modern 3D flight.

The new 61B-P carburetor incorporates an integral regulator and is equipped with a thermo-insulator to prevent heat transfer to the air/fuel mixture. The black anodized, diecast aluminum head has unique laser markings which symbolize sharp 3D maneuvers. The combustion chamber has been designed to utilize higher nitro content fuels widely used for 3D flight.

As with the MAX-91HZ, a light weight piston is utilized resulting in a lower vibration level and increased performance. Five holes drilled in the head of the piston that intersect the backside of the piston ring allow combustion gases to expand the ring resulting in an increased compression seal and more combustion energy transferred to the engine's crankshaft


  • PD-08 pump works with a matched 61B-P carburetor and integral regulator to deliver a steady fuel supply at any attitude even during the most adventurous 3D manuevers
  • Short rectangular heatsink can be entirely enclosed inside cooling shroud to lower operating temperatures
  • Newly designed piston and crankshaft further reduces vibration and improves torque stability over entire RPM range
  • Thermo insulator on carburetor blocks engine heat to ensure more stable fuel/air mixture
  • Pull pull throttle setup


  • Displacement: 0.91 cu in (14.95 cc)
  • Bore: 1.09 in (27.7mm)
  • Stroke: 0.98 in (24.8mm)
  • Practical RPM: 2,000 - 16,000
  • Power Output: 3.4 hp @ 15,000 RPM
  • Weight: 1.4 lb (635g)

Package Included:

  • O.S. Max 91 HZ-PS Ringed Helicopter Engine
  • Instruction Manual
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O.S. Max .91 HZ-PS 3D Competition Helicopter Engine

  • Brand: OS
  • Product Code: OS:OS-18620
  • Availability: In Stock
  • $370.00USD

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