RCV 91 CD Engine. 4- Cycle Rotary Valve System (CODE 489)

This engine is new in box.
The RCV 91 CD is a unique four-stroke glow engine that uses a Rotating Cylinder Valve system instead of traditional poppet valves. This design allows for a much more compact, low-profile engine—roughly the size of a standard .60 2-stroke—making it easier to fit inside aircraft cowlings.

Displacement: 15 cc (0.91 cu in).
Power Output: 1.5 BHP at 9,800 RPM.
Practical RPM Range: 2,400 to 12,000 RPM.
Weight: 765g (26.96 oz).
Glow Plug: Specifically recommended to use an OS Type F.
Operating Recommendations
Fuel: Methanol-based with 10% Nitromethane. The oil content should be approximately 15%, with a mix of 3% to 6% Castor oil to aid in cooling and sealing the rotary valve.
Propellers: Unlike the RCV “SP” series (which are geared 2:1), the “CD” (Crank Drive) series is direct drive and uses conventional props.
Running-in: 14×6 APC.
General Flying: 13×6 to 14×8.
Cooling: Because 4-strokes run hotter and this design has unique internal friction, ensuring a large air outlet (2:1 or 3:1 ratio compared to the inlet) is critical to prevent overheating.
Unique Features
No Valve Adjustments: Since there are no rocker arms or springs, there is no need for periodic valve clearance adjustments.
Low Profile: The height is significantly less than standard OHV engines (approx. 18mm lower than comparable OS or Magnum models), allowing for much cleaner scale installations.