All engines generate vibration, any engine builder can tell you that. Balancing rotating assemblies both statically and dynamically has been the long-term strategy for attenuating unwanted vibration, but like any fine, hand-crafted musical instrument, all engines have harmonic frequencies where damage can occur.
Externally dampening the power pulses that inherently plague any “V” configuration engine is a tried and true supplement to internal balancing, and not something to be overlooked. If you paid attention in high school physics, you know that there are universal laws of energy and matter – specifically conservation of the two. Vibrations are kinetic energy (i.e. movement), and you can never destroy energy or matter, only change it to a more agreeable phase.
In the case of engine harmonic dampers like the viscous silicone-filled Fluidampr, kinetic energy in the form of potentially damaging harmonic vibration is converted to non-threatening thermal (heat) energy through the friction of shearing action. We were intrigued by this clever manipulation of the laws of nature in the name of engine performance, so we sat down with Brian LeBarron and Aaron Neyman of Fluidampr for a deeper look.
Shearing action is the fundamental device that the Fluidampr employs to convert energy from vibration to heat. How this is achieved is a matter of design.
“The outer housing and hub of the Fluidampr is fixed to the crankshaft with either a press fit or bolt flange. As you encounter RPM ranges with critical end-to-end twisting and rebounding of the crankshaft (torsional vibration), the fluctuation attempts to drag the inner inertia ring along, too. The inertia ring, however, has to overcome the silicone. Naturally there is resistance. Given the amount of force and rate of velocity change the crankshaft is experiencing, the counter effect of the inertia mass and shear will keep exponentially reducing the magnitude of vibration. The process converts energy to heat,” LeBarron summarized.
The materials selection process is equally integral to the function of the harmonic damper, conventional rubber dampers from many OEMs can dry, crack and deteriorate over time. Inferior silicone substances can also dry and decay, but by using a silicone that stands up to the demands of an automotive environment Fluidampr harmonic balancers can stand the test of time.
“Silicone is more thermally stable and durable over conventional rubber. This is one reason we find silicone or silicone blends incorporated into a wide variety of automotive parts today. In terms of controlling engine harmonics, silicone is a superior dissipater of heat. This allows it to provide consistent performance and long term durability. Fluidampr performance dampers use a proprietary silicone that maintains the viscosity tolerance needed for reliable damping across an extreme temperature range of -40 degrees F to 300 degrees F,” LeBarron explained.
“The silicone fluid acts as a soft spring that couples the inner inertia ring to the outer housing. The fluid is not bonded to the inertia ring and housing, this gives a broad band of effectiveness to the Fluidampr,” comments Neyman, Fluidampr’s Sr. Product Engineer and Torsional Vibration Analysis Specialist. “Rubber based products are either bonded or run a heavy press fit, which limits the damper’s effectiveness to a small frequency band. Knowing this, rubber dampers rely heavily on the ‘tune’ of the rubber material and usually require multiple dampers per engine family. The flexibility of the fluid spring offers one damper for a family of engines, from stock daily drivers to Pro Street to full race builds; the broad band damping effect of a Fluidampr allows the engine to be protected from torsional vibrations.”
When you get into the complex physics of combining fluid dynamics, material science and energy phase changes in a multi-variable environment, you need some data to back up your theories.
Testing in a lab is a necessity to meaningful research and development. Using a device called a Hooke’s Joint machine, accelerated wear at varied vibration harmonics can be tested while thermal imaging and vibration data is collected.
“The Hooke’s Joint machine is capable of generating 10 times the vibration amplitudes found in an engine. We can generate a tremendous amount of heat to simulate the life of an engine in a much shorter period of time,” says Neyman. “Thermal imaging technology really helps demonstrate the operation of a viscous damper. They are like a radiator when sized properly. Viscous dampers are quite common in applications with low air flow, like in the cabin of boats, agricultural equipment, and stationary industrial installations. If the application is specified as low air flow in advance, a Fluidampr can be designed to handle the most stagnant conditions, without sacrificing damper longevity.”
“Heat is the enemy of engines,” is a common sentiment for good reason, so converting vibrations to heat may seem like trading one problem for another. Fluidampr designs within an envelope of operating temperatures, so as not to defeat the purpose of a damper upgrade.
“Heat can be a destructive force as well. The goal is to maintain generated heat below the damper’s ability to dissipate it. To preserve damping integrity, the silicone itself is an excellent dissipater. To further draw heat away and radiate it from the damper, the outer housing doubles as a heat sink. Black zinc anodized steel is often used in Fluidampr products for this purpose. A properly functioning viscous damper will run hotter than the ambient engine bay temperature,” LeBarron explained.
Collecting numbers in a sterile lab environment is all well and good in the name of scientific method, however most of you reading this are probably screaming at your screens saying we race on tracks not in labs! Real world testing is another integral part to continually improving engine technology.
“At the track is where it matters. We sample ‘high mileage’ dampers, commonly from circle track and drag racing applications. In house we’ll run a log decay test against a new benchmark damper and confirm that the damper meets operating tolerances. From there we’ll cut it open and perform a thorough analysis of the silicone to confirm performance,” LeBarron assured us.
“OE viscous dampers are not intended for race applications. Fluidampr performance dampers are SFI 18.1 certified and engineered to perform under the harsh conditions of professional racing.”
Applications for Fluidampr harmonic balancers range across most all domestic, import, and diesel applications for both street and race vehicles.