O.S. .91 HZ-R 3D Speed Competition 3D Helicopter Engine w/61G Carburetor

This is the O.S. .91 HZ-R 3D Speed Competition 3D Helicopter Engine, with 61G carburetor. O.S. has taken high-performance, high-speed helicopter engines to the next stage of evolution with the introduction of the 91HZ-R 3D Speed. This engine offers unique features that give pilots a distinct advantage in 3D competition, like the Demand Regulator System, which supplies the carburetor with a consistent fuel supply regardless of the level of fuel in the tank, or the attitude of the helicopter. A re-designed combustion chamber has been shaped to match the big bore carburetor and advanced exhaust cylinder timing providing optimum performance, while the lightweight, CNC machined cooling head and black anodized crankcase provides efficient cooling in the harshest conditions.
91HZ-R 3D Speed Features:

• Designed for all-out, aggressive 3D competition.
• Offers incredibly stable mid-range torque for awesome 3D flight
• Carburetor inlet enlarged to 11.2 mm
• Exhaust port timing set at 165°
• Combustion chamber shaped to match the big bore carburetor and advanced exhaust cylinder timing
• Demand Regulator System (DRS) guarantees a steady fuel supply to the carb at any attitude, on a full or empty tank and during the most abrupt throttle changes
• Lightweight, machined cooling head
• Crankshaft counter weight has been modified to reduce vibration at high RPM
• Black anodized crankcase offers better heat dissipation

Specifications:
Displacement: 0.91 cu in (14.9cc)
Bore: 1.09 in (27.7mm)
Stroke: 0.98 in (24.8mm)
Output: 3.6 hp @ 15,500 rpm
Practical RPM: 2,000-16,500
Weight: 21.2 oz (603g)
Requirements: 10%-30% nitro fuel with at least 18% lubricant content