ATI Super Damper Crank Pulley EJ205 EJ257 Fits Subaru WRX Sti

Much like many other factory parts in your engine, the crank pulley is a wear-item with a shelf-life. The rubber pieces in the factory damper can deteriorate over time, causing a failure that could result in pistons hitting the valves, and destroying your engine. Also, factory crank pulleys were designed to operate at a certain speed and maximum rpm. When racing an engine, we often rev it higher than it was designed to from the factory, pushing many of the factory parts past their design criteria closer to failure.
For this reason, many sanctioned race classes require an "SFI Approved" crank pulley/damper, and will not even allow factory crank pulleys through inspection. 

ATI Performance Products, Inc. is proud to introduce its renowned Super Damper for Subaru EJ20, EJ22 and EJ25 engines -- Part # 917991. Unlike undampened underdrive pulleys, which offer no protection to high performance engines, the ATI Super Damper provides balanced dampening of torsional crankshaft vibrations at all RPM levels. The ATI Super Damper comes with laser-etched timing marks and is a direct replacement for the OEM unit. The ATI Super Damper is a critical component for all high performance cars to help protect against engine harmonics and features a dual four-groove serpentine belt drive on the outer shell to utilize the factory serpentine belt set-up. All ATI Super Dampers exceed SFI 18.1 Safety Certification and are approved for competition use.

The patented ATI Super Damper is the only damper designed exclusively for high performance engines:
- Eliminates torsional crankshaft vibrations 
- Exceeds SFI 18.1 specs 
- Laser engraved timing marks 
- Black zinc chromate finish 

Damper Components: Hub, Outer Shell, Inertia Ring and Bolt Kit.