ATI Super Damper for Honda/Acura K Series Engines

ATI Super Damper - Honda/Acura K20/K24 (Street & Race)

The crank pulley on a K-series is also its harmonic damper, it absorbs the torsional vibration the crankshaft produces on every combustion event, and on a high-revving built K20 or K24, that job gets critical. The ATI Super Damper is the upgrade for it: a two-piece steel-hub, aluminum-shell damper using ATI's proven elastomer technology to cancel that vibration across the whole rev range, SFI 18.1 certified for competition. It protects the bearings, smooths power delivery, and lets you spin past 9,000 rpm without worrying about pulley failure. Available in Street and Race spec depending on your accessory setup.

Street or Race: Pick Based on Your Accessories

The two versions come down to whether you're keeping air conditioning and power steering, and they're different pulley diameters to match.

Street (918477), AC and PS retained, 5.67". This version keeps the factory six-rib serpentine layout, so it drives your air conditioning and power steering like stock. If your car still has AC and power steering, this is the one, it's a direct replacement that retains all your accessories, at the 5.67" diameter correct for the stock accessory drive. It also adds 360° laser-etched timing marks for easier cam timing.

Race (918478), no AC or PS, 7.074". This version is for a car that's had the air conditioning and power steering deleted, a common move on a dedicated track or race build to shed weight and parasitic drag. With those accessories gone, the Race damper runs the larger 7.074" diameter set up for that stripped configuration.

So the choice is simple: if you're running AC and power steering, get the Street version (5.67"); if you've deleted them for a race build, get the Race version (7.074"). Match it to how your car is actually set up.

What a Harmonic Damper Does

Worth understanding, because it's doing more than spinning your belts.

A crankshaft doesn't rotate perfectly smoothly, every combustion event twists it and it springs back, setting up torsional vibration along its length. Left unchecked, that vibration is genuinely destructive, it fatigues the crank, wears the bearings, and at high RPM can cause the factory pulley's bonded rubber to fail, which throws your belts and can damage the front of the engine.

A harmonic damper absorbs that vibration. The ATI uses a tunable elastomer design that's far more effective and durable than the factory bonded-rubber pulley, it cancels the vibration across the entire rev range rather than at one frequency, and it won't come apart at high RPM the way a degraded stock pulley can. For an engine that lives at high RPM, that protection is exactly what you want, and it shows up as smoother power and longer bearing life.

Built for Competition

The construction and certification are serious.

It's a two-piece steel hub and aluminum shell, engineered and machined in the USA, and it's SFI 18.1 certified, which is required for NHRA and IHRA competition. If you race in a sanctioned class that mandates an SFI damper, this passes tech, bolt it on and it's handled.

It's also fully rebuildable, ATI offers service kits and replacement elastomers, so it's a buy-once part you can maintain and re-tune rather than replace, unlike the sealed factory pulley.

Pulley Sizing and Accessory Speed

A useful detail for tuning your setup.

The Street version's 5.67" diameter is the correct size for the K20A2 and K20Z3 stock accessory drive. On larger-pulley K24s it functions as a mild underdrive, and on the smaller-pulley K20Z1 as an overdrive, so depending on your engine you can fine-tune accessory speed with belt choice. The Race version runs a larger 7.074" diameter for the accessory-delete setup. Either way, if you change the pulley ratio from stock, check your belt length, you may need a different belt to suit the new diameter.

Fitment

2002-2015 Honda Civic Si
2002-2006 Acura RSX Base/Type-S
2004-2008 Acura TSX
2003-2007 Honda Accord (K24)
2002-2006 Honda CR-V
2003-2011 Honda Element
2007-2010 Acura CSX Type S

K20/K24, and K-series swaps using the factory crank bolt pattern. Street (918477, AC/PS retained, 5.67") or Race (918478, no AC/PS, 7.074"). Includes damper, hub, and hardware.

If you're building a high-revving K-series and want to protect the crank and bearings with a proper harmonic damper instead of trusting the aging factory pulley, this is the one, SFI-certified, rebuildable, and tuned to cancel vibration across the rev range. Pick Street if you're keeping AC and power steering (5.67"), Race if you've deleted them (7.074"), confirm your belt length if you change the ratio, and spin it to redline without worrying about the pulley.