O.S. 55HZ-R DRS Ringed .55 Helicopter Engine

O.S. 55HZ-R DRS Ringed Competition Helicopter Engine

The O.S. 55HZ-R DRS is the evolution of the legendary 55HZ-H Hyper, developed to meet the increasing demands of modern F3C competition flying and aggressive 3D helicopter aerobatics. While sharing the same proven ringed piston design and displacement as the popular 55HZ-H, the 55HZ-R introduces O.S.'s innovative Demand Regulator System (DRS) for significantly improved fuel delivery consistency and tuning stability.

The DRS system maintains a controlled fuel supply throughout the entire flight, delivering a more consistent air-fuel mixture from a full tank to nearly empty. This results in more predictable engine performance, improved throttle response, easier tuning, and more stable governor operation under varying flight loads and attitudes.

For pilots seeking the ultimate performance from a .55-class nitro engine, the 55HZ-R DRS offers all the power and reliability of the 55HZ-H Hyper while adding a sophisticated fuel regulation system that helps maximize consistency during demanding flight maneuvers.

Why Choose the 55HZ-R DRS Over the 55HZ-H?

• DRS fuel regulation system provides more consistent fuel delivery throughout the entire tank.
• Improved mixture stability during aggressive 3D and competition flying.
• Reduced tuning changes between full and empty fuel tanks.
• More stable governor performance and head speed consistency.
• Better fuel metering across a wide range of flight attitudes.
• Higher practical RPM range compared to the standard 55HZ-H.

Key Features

• Genuine O.S. Engines .55-class competition helicopter engine
• Demand Regulator System (DRS) for precise fuel delivery and consistent engine performance
• Ringed piston design for excellent durability and long service life
• 40L-R dual-needle carburetor with independent mixture adjustments
• Four-arm throttle lever compatible with a wide range of servo geometries
• Optimized regulator placement aligned with the carburetor for consistent operation in all flight attitudes
• Same mounting bolt pattern as the O.S. 50SX-H Hyper
• Low-profile six-fin HZ Hyper cooling head
• Excellent choice for F3C competition and demanding 3D flying
• Outstanding throttle response and fuel metering precision

Applications

The O.S. 55HZ-R DRS is ideally suited for high-performance 550-600 class 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 helicopter kits 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 – 20,000 RPM
• Weight: 15.1 oz (429g)
• Carburetor: O.S. 40L-R Dual-Needle Carburetor
• Fuel System: O.S. Demand Regulator System (DRS)

RotorQuest Notes: The 55HZ-R DRS is widely regarded as the premium version of the 55HZ platform. While the 55HZ-H remains an excellent traditional nitro engine, the 55HZ-R offers improved fuel consistency, easier tuning, and more stable performance throughout the flight. For pilots building a Kraken 580 Nitro, RAW 580 Nitro, Tron 5.8 Nitro, or other modern 580-class nitro helicopter, the 55HZ-R DRS represents the highest-performance .55-class engine produced by O.S. Engines.