The Lycoming IO-390 series is a family of modern, fuel-injected, four-cylinder, horizontally opposed (flat-four), air-cooled aircraft engines designed for light general aviation and experimental aircraft. These engines are part of Lycoming's Thunderbolt series, which emphasizes performance, efficiency, and reliability.

Part Number

General Specifications:

• Engine Type: 4-cylinder, horizontally opposed (flat-four)
• Displacement: 390 cubic inches (6.4 liters)
• Power Output: 210 horsepower (157 kW) at 2,700 RPM (varies slightly by model)
• Compression Ratio: 8.9:1
• Fuel System: Fuel injection (Airflow Performance or equivalent)
• Cooling System: Air-cooled
• Weight: Approximately 267 lbs (121 kg) dry
• Fuel Type: 100LL aviation gasoline (avgas) or unleaded alternatives (if approved)
• Oil Capacity: 8 quarts (7.6 liters)

Key Features:

• Fuel Injection: Provides precise fuel delivery, improved efficiency, and better performance at varying altitudes.
• Lightweight Design: Optimized for light sport, experimental, and modern certified aircraft.
• High Power-to-Weight Ratio: Delivers strong performance for its size.
• Modern Engineering: Incorporates advanced materials and design for improved durability and reliability.
• mooth Operation: The horizontally opposed configuration reduces vibration.

Popular Models in the IO-390 Series:

The IO-390 series includes several models, each tailored for specific aircraft and performance requirements. Some of the most common models are:

• IO-390-C (IO-390-C1B6, IO-390-C3B6): 210 hp, used in experimental and light sport aircraft like the Van's RV-14 ,Cirrus SR20.
• IO-390-A (IO-390-A3A6, IO-390-A3B6): 210 hp, used in certified aircraft like the CubCrafters XCub.
• IO-390-EXP119: A variant designed for experimental aircraft with specific performance requirements.

Applications:

The IO-390 series powers a variety of aircraft, including:

• Experimental and Kit-Built Aircraft: Such as the Van's RV-14, RV-10, and other high-performance homebuilts.
• Certified Aircraft: Like the CubCrafters XCub and Carbon Cub SS.
• Light Sport Aircraft: Ideal for modern LSA designs requiring a compact, high-output engine.

Maintenance and TBO:

• TBO (Time Between Overhauls): 2,000 hours or 12 years, whichever comes first (under normal operating conditions).
• Maintenance: Regular oil changes, inspections, and adherence to Lycoming's service bulletins are essential for optimal performance.

Advantages:

• Efficiency: Fuel injection and modern design contribute to better fuel economy.
• Performance: Ideal for aircraft requiring a compact, high-output engine.
• Versatility: Suitable for both experimental and certified aircraft.
• Reliability: Built with modern engineering and materials for enhanced durability.

Comparison to IO-360 Series:

The IO-390 is a larger-displacement engine (390 cubic inches vs. 360 cubic inches) and produces more power (210 hp vs. 180-200 hp).

It is often chosen for aircraft requiring higher performance or for upgrades to older airframes.