What Is A Harmonic Balancer, aka Crankshaft Damper?
A harmonic balancer reduces destructive crankshaft torsional vibration, which is the end-to-end twisting/rebound motion, that is naturally generated during each power stroke. A harmonic balancer contributes to greater valve train and timing efficiency, plus reduces wear of critical engine components such as main bearings, oil pump and the crankshaft itself.
A harmonic balancer often incorporates the main drive pulley and by appearance is often overlooked as having no essential function to the life of the engine. If the drive pulley is incorporated with the harmonic balancer, removing or changing it to a lightweight design, or using a low quality product MAY BE THE SINGLE BIGGEST COSTLY MISTAKE YOU CAN DO TO YOUR ENGINE.
Why Do I Need A Performance Harmonic Balancer, aka Crankshaft Damper
Performance parts that increase torque, such as intake, exhaust, cams, and ECM changes typically cause an increase in torsional vibration magnitude, but keep frequency the same. Evidence that your stock harmonic balancer is not performing adequately will be cracked, bulging or missing rubber between the hub and outer ring. This is caused by excessive heat retention, over stretching and age. A common failure will be the outer ring separating from the hub causing damage inside the engine bay. Most race sanctioning bodies require a SFI 18.1 spec damper as a safety caution.
Performance parts related to the rotating assembly, such as rods, pistons, crank, flywheel/flexplate usually changes both torsional vibration magnitude and frequency. A stock harmonic balancer typically is only tuned for a 50hz peak variance. Move beyond its parameters and it may leave your critical engine components unprotected when torsional vibration is at its peak.
Due to the countless combinations of performance upgrades the simplest and more effective solution is to install a Fluidampr performance damper. By design, Fluidampr protects across a broad frequency and can become more effective as magnitude increases. The earlier a Fluidamper performance damper is installed, the more you’ll benefit from the protection, performance and durability in the long run.
How Does A Fluidampr Damper Work?
Unlike a stock elastomer harmonic balancer, Fluidampr performance dampers protect across a broad frequency range and can become more effective as magnitude increases throughout your RPM range. Each Fluidampr performance damper is designed for the engine application it is intended for.
Fluidampr performance dampers consist of a free rotating inertia ring inside a laser sealed outer housing within tight tolerance of each other. Both the inertia ring and the outer housing are computer balanced to exceed OEM specifications during manufacturing. Between the two, an area referred to as the shear gap is pressure injected with viscous silicone. This specialized silicone maintains stability across an extreme temperature range and provides superior heat dissipation.
As soon as your engine fires torsional vibration is present. To damp its destructive effects, the outer housing turns at engine RPM, while the inner inertia ring immediately self-centers and is free to be ‘shocked’ by each torsional vibration event. As the inner inertia ring moves in-and-out of RPM with the outer housing, the shearing force through the silicone transforms the vibration to heat, which rapidly dissipates through the housing. Since the mass of the inertia ring is engulfed in a thin film of silicone and not directly connected to the crank, it can be calculated that only 2/3 of the total Fluidampr weight is rotating at RPM. For example, a 7.9lb Fluidampr for a Chevy LS1 only feels 5.3lbs at rpm.
The Fluidampr design originated from top race engine builders requesting Vibratech TVD (formally Houdialle and parent company to Fluidampr) to bring its viscous damper technology engineered for long-life, high power diesel applications to professional motorsports in the early-1980s to replace failing elastomer designs. Viscous torsional dampers are used today as original equipment on select luxury sportscars, light-duty diesel trucks and even military spec engines. Meanwhile, nearly all high power engines that move our economy depend on a viscous damper for superior protection, performance and durability.
When To Upgrade Your Harmonic Balancer
The harmonic damper protects from destructive crankshaft torsional vibration that occurs naturally from internal combustion and improves overall efficiency. Properly controlling torsional vibration increases torque and horsepower, improves main bearing life and valve train operation, plus reduces the risk of crank failure.
When To Upgrade Your Harmonic Balancer
The majority of passenger car and light trucks come equipped with an elastomer style harmonic balancer. These low-cost, rubber-based OEM harmonic balancers are tuned from the factory to protect only a narrow band of the worst harmonics and are intended for stock conditions. Performance upgrades that increase torque such as an air kit, exhaust, tuner and injectors or carburetor will increasingly accelerate elastomer harmonic balancer failure. Performance upgrades that change the composition of the rotating assembly such as, pistons, rods and flexplate/clutch or flywheel/torque converter will cause the OEM damper to be out-of-tune to provide optimum protection.
The harmonic balancer is a fundamental building block of engine performance. An upgrade should be done in conjunction with your basic air kit, exhaust, and tuner setup for optimum long term performance. If you have already performed this set up without upgrading, then the stock harmonic balancer is working harder to compensate for the added torque. Routinely inspect the rubber layer of the stock harmonic balancer for signs of cracked, bulging or missing rubber. These signs indicate that an elastomer harmonic balancer is deteriorating and may not be properly protecting your engine. Elastomer harmonic balancer age, exposure to the elements, oils and solvents, and excessive towing/hauling will also accelerate the breakdown of the rubber layer.
Cracked, bulging and missing rubber are early warning signs that your stock elastomer style harmonic balancer needs to be upgraded to a viscous damper.
Beyond a basic performance set up, a broad band viscous damper upgrade, such as a Fluidampr performance damper is a requirement and needs to be installed with any rotating assembly changes. The reason is that different pistons, rods, crank, flywheel/torque converter or flexplate/clutch will potentially shift the damaging harmonics out-of-range of where the stock tuned elastomer harmonic balancer is designed to protect. By design, a viscous damper provides long lasting protection across a broad range of harmonics and is the most cost effective approach. Only a professional torsional vibration analysis based on your specific parts combination will determine the durometer needed for other aftermarket o-ring based performance dampers, then rountine o-ring replacement is required.
Where To Buy Fluidampr Performance Dampers
Fluidampr performance dampers are sold through quality performance service shops and parts retailers. Click here to find one near you. If you have questions or need assistance, Fluidampr technical support is available 8:00am – 4:30pm EST, Monday through Friday at (716) 592-1000 or email here.
Inside a Fluidampr performance damper.
Using only three parts (a laser-welded sealed housing, an internal inertia ring, and highly viscous silicone fluid between the two), these SFI-approved Fluidamprs can control all crankshaft vibration--not just a limited frequency range. As a result, you get reduced wear on the main bearings and timing gear, more stable valvetrain operation, and less chance of crank failure.