ATI Damper 5.50in Aluminum 4 & 5 Groove 1Pc (Subaru WRX EJ2.0L / 2.2L / 2.5L Engine) ATI917991
Lightweight Aluminum Super Damper for Subaru WRX EJ Engines (2.0L / 2.2L / 2.5L)
The ATI 5.50-inch Aluminum Super Damper (part ATI917991) is designed specifically for Subaru EJ-series engines including EJ20, EJ22, and EJ25 powerplants found in WRX and STi applications. Featuring a compact 5.50-inch diameter and precision-balanced 1-piece aluminum design with 4 and 5-groove pulleys, this damper provides maximum harmonic control, improved throttle response, and reduced rotating mass perfect for street, track, or boosted Subaru builds.
Performance Highlights
- 5.50-inch outer diameter provides compact size for tight engine bays
- 1-piece aluminum construction reduces rotational weight for faster revs
- 4- and 5-groove pulley configuration supports factory and aftermarket accessory drives
- Engineered for EJ20, EJ22, and EJ25 engines used in WRX, STi, and other Subaru platforms
- SFI 18.1 certified and fully rebuildable for long-term use
Quick Specs
- Outer Diameter: 5.50 inches
- Material: Aluminum
- Pulley Type: 4 & 5 Groove
- Design: 1-Piece Super Damper
- Certification: SFI 18.1
- Applications: Subaru WRX EJ20, EJ22, EJ25 Engines
- Part Number: ATI917991
Why Choose ATIs 5.50in EJ-Series Super Damper?
The ATI917991 is precision-engineered to handle the unique torsional frequencies of Subarus flat-four engines. Its compact aluminum body minimizes inertia while maintaining exceptional balance and durability. Whether youre running a high-boost street car or a full race build, this damper ensures smoother operation, better power delivery, and improved engine longevity under high RPM conditions.
Frequently Asked Questions
Will this fit all Subaru EJ engines?
Yes. The ATI917991 fits EJ20, EJ22, and EJ25 engines commonly found in WRX, STi, and similar Subaru platforms.
Can this damper handle turbocharged or high-boost setups?
Absolutely. Its designed to handle the torsional stress and vibration from high-boost and high-RPM applications.
Does it support factory belt configurations?
Yes. The 4- and 5-groove pulley design accommodates both OEM and upgraded accessory systems.
Is it rebuildable?
Yes. Like all ATI Super Dampers, the ATI917991 is fully rebuildable with official ATI components.
Vehicle Fitment
- Subaru WRX EJ20 2.0L (20022005)
- Subaru WRX EJ22 2.2L (Legacy / Impreza applications)
- Subaru WRX & STi EJ25 2.5L (20062014)
- Subaru Forester XT EJ25 2.5L Turbo
- Subaru Legacy GT EJ25 2.5L Turbo
Contact Beefcake Racing
Beefcake Racing offers the complete selection of ATI Super Dampers for Subaru and other performance platforms. For orders or technical questions, email sales@beefcakeracing.com or call 1-855-827-7223. Our experts can help you find the perfect damper for your WRX, STi, or custom EJ build.
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