ATI Damper – 5.50in – Alum – 4 & 5 Grv – Subaru WRX EJ20 22 25 Engine 1Pc

ATI Super Damper 917991 is an engine and drive-system specific harmonic damper in the 5.50in – Alum – 4 & 5 Grv – Subaru WRX EJ20 22 25 Engine 1Pc configuration. Confirm the crankshaft, balance requirement, hub, shell, diameter, groove arrangement, accessory drive, and every ATI application note before ordering.

Fitment

This component is selected by engine, crankshaft, damper, hub, balance, and drive-system specifications rather than by vehicle name alone. Do not use year, make, and model as the only compatibility check.

Specifications

What’s Included

One new ATI component identified by manufacturer part number 917991. Hubs, pulleys, belts, bolts, washers, spacers, keys, tools, and installation hardware are included only when expressly stated for this exact part number.

About ATI Performance Products

ATI develops tunable and serviceable Super Dampers, crank hubs, pulleys, transmission components, and engine service hardware for performance and competition applications. Compatibility remains exact-part and engine-system specific.

Related ATI Components

• ATI Damper – 5.67in – Alum – (2) 4 & 5 Grv – Nissan – SR20 Rwd – Street – 1Pc
• ATI Damper – 5.67in – Alum – (2) 4 Grv – Toyota Supra – 7M-Ge / GTe 3L – 87-92 – 800HP Max – 1Pc
• ATI Damper – 5.67in – Alum – (3) 4 Grv – Nissan 300ZX – V6 – 800HP or Less – 1Pc

Browse the ATI collection for additional dampers, pulleys, and service components.

Frequently Asked Questions

Does ATI 917991 match my engine and accessory drive?
Match the engine family, crank snout and keyway, balance type, hub, outside diameter, belt grooves, accessory drive, and every application note. The stated configuration is 5.50in – Alum – 4 & 5 Grv – Subaru WRX EJ20 22 25 Engine 1Pc.

Is this ATI Super Damper rebuildable?
ATI Super Dampers are serviceable. Inspect the shell, hub, fasteners, timing marks, and elastomers according to the current ATI instructions and service intervals.

Do I need a special installer for this damper?
Use the correct crankshaft damper installation tool and the exact fastener, washer, spacer, key, hub, and torque procedure for the engine. Never hammer the damper onto the crankshaft.

Installation Instructions

Use the current ATI instructions and the engine manufacturer’s service information. Verify crankshaft and hub condition, key and spacer placement, required installer, fastener and washer, runout, pulley alignment, belt routing, clearances, and final torque. Never draw the damper on with an undersized or partially engaged bolt.