ATI Performance Products ATI917991 Super Damper Harmonic Balancer Aluminum - 5.50

The ATI Performance Products Super Damper is a high-performance harmonic balancer engineered specifically for Subaru EJ20, EJ22, and EJ25 engines found in WRX and STI applications. This precision-balanced damper provides superior protection against destructive torsional crankshaft vibrations at all RPM levels, making it an essential upgrade for street, track, and boosted builds.

Key Features:

• 5.50-inch outer diameter aluminum construction with 3-ring elastomer design
• Dual serpentine belt configuration with 4-groove and 5-groove pulley options
• Exceeds SFI 18.1 safety certification for competition use
• Laser-engraved 360-degree timing marks for precise tuning
• Black zinc chromate finish for corrosion resistance
• Internally balanced design for direct OEM replacement
• Fully rebuildable and tunable for long-term performance
• Total weight: 5.80 lbs (3.60 lbs inertia ring, 2.20 lbs hub)

Unlike undampened underdrive pulleys that offer no vibration protection, the ATI Super Damper utilizes computer-machined grooves with proper durometer O-rings to eliminate harmful harmonics throughout the entire RPM range. The aluminum shell reduces rotational mass for improved throttle response while the steel inertia weight provides the damping performance high-performance engines demand. Factory equipment on various crate engines and approved for NHRA and IHRA competition.