O.S. .91 HZ-R 3D Speed Competition 3D Helicopter Engine w/61G Carburetor
About this part
Engine Overview:
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
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
CA Residents Prop 65 Warning
WARNING: This product can expose you to chemicals including Di(2-ethylhexyl)phthalate (DEHP), which is known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov Details...Reviews5.0 · 3 reviews
I have this motor with the Powerboost Pipe combo. All I can say in one word to describe this motor: FANTASTIC! Currently installed in my T700N LE FBL, Im running 14deg pitch, and 10deg cyclic! With my old motor (ys 91 3ds) I could only run about 13deg MAX. The recovery and torque this motor has is outstanding. I can do sustained elevator tic-toc's, and aileron tic-toc's effortlessly. Running 30% Byron Rotor Rage with .002 shim. A couple notes to get max performance from this motor: -Run an OS#8 or an Enya #3 -Use BOTH shims included with the motor if you're going to run 30%. It allows the needles to be not so sensitive, without any adverse effect on power! -Make sure your plumbing is absolutely air tight. Sealed. ANY leaks and you could be chasing needles non-stop! -My needle settings at 85deg F. 40% humidity: Low- Stock position. Mid- 3/4 turn out. High-1-3/4 turn out.
So happy to have a new 91 speed 3d. OS is the goat for this. P.S if you could just rerelease the powerboost 90 id be in heaven. ;) thanks
Thank you O.S.!!! We've all been hoping and waiting for another production run of the infamous .91 HZ-R 3D Speed.
All three reviewers are highly positive, each giving five stars. One owner reports running the engine in a T700N LE flybarless helicopter with a Powerboost pipe, citing higher pitch and cyclic settings than with a previous engine and strong recovery and torque in 3D flight. That reviewer also recommends a specific plug (OS #8 or Enya #3), using both included shims at 30% rotor setups, and careful plumbing. Another reviewer welcomes the return of the model and asks for the Powerboost pipe to be reissued for the .90 engine. A third is pleased the production run has resumed. No negative points are raised. Reviews are few and largely enthusiastic, so the evidence base is limited.
- + Strong recovery and torque
- + Allows higher pitch and cyclic settings
- + Good for sustained 3D maneuvers
- + Welcomed as a return to production
- − Requires careful plumbing and tuning
- − Requested reissue of a related pipe for the .90 engine