O.S. 55 HZ-H Hyper Ringed Competition Helicopter Engine

O.S. 55HZ-H Hyper Ringed .55 Helicopter Engine

The O.S. 55HZ-H Hyper Ringed is one of the most successful .55-class nitro helicopter engines ever produced. Designed specifically for high-performance RC helicopters, the 55HZ-H delivers impressive power, crisp throttle response, and legendary O.S. reliability in a compact package.

Developed to provide power comparable to many .60-class helicopter engines while maintaining the weight and footprint of a traditional .50-size engine, the 55HZ-H quickly became a favorite among sport and 3D pilots worldwide. Its proven ringed piston design offers excellent durability, consistent compression, and long service life, making it an outstanding choice for both new builds and replacement applications.

Equipped with the O.S. 40L dual-needle carburetor, the 55HZ-H provides smooth fuel delivery and precise tuning for reliable performance throughout the flight envelope.

Key Features

• Genuine O.S. Engines .55-class helicopter engine
• Power output comparable to many .60-size helicopter engines
• Proven ringed piston design for extended engine life and durability
• Compact dimensions with excellent power-to-weight ratio
• O.S. 40L dual-needle helicopter carburetor included
• Four-arm throttle lever compatible with a wide variety of servo geometries
• Same mounting bolt pattern as the popular O.S. 50SX-H Hyper
• Smooth throttle response and reliable tuning characteristics
• Ideal for sport, aerobatic, and demanding 3D flight
• Legendary O.S. quality, performance, and reliability

Applications

The O.S. 55HZ-H is ideally suited for modern 550-600 size nitro helicopters, including:

• SAB Kraken 580 Nitro
• SAB RAW 580 Nitro
• ALIGN T-REX 600XN Nitro
• Tron 5.8 Nitro
• OXY 5 Nitro
• Other 550-600 class nitro helicopters and custom nitro conversions

Specifications

• Displacement: 0.55 cu in (8.93cc)
• Bore: 0.91 in (23.0mm)
• Stroke: 0.85 in (23.5mm)
• Practical RPM Range: 2,000 – 17,000 RPM
• Weight: 14.39 oz (408g)
• Carburetor: O.S. 40L Dual-Needle Helicopter Carburetor

RotorQuest Notes: The O.S. 55HZ-H remains one of the best engine options for 550-600 class nitro helicopters. Its combination of .60-class power, proven reliability, readily available parts support, and straightforward tuning continues to make it a popular choice among nitro enthusiasts.