There is an engine builder that goes to my church that will wax eloquent for hours on topics like this - when asked for his thoughts on this, he basically said that for the most part, automotive "Crankshaft Torsional Absorbers" are tuned to a specific frequency predicated on the engine design as produced at the factory. . . and it is affected by flywheel / clutch inertia, transmission type, piston weight, crankshaft counterweights, bla bla bla . . . his thought is that with any non-stock motor and drivetrain that it is highly unlikely that the "CTA" that is on the motor is optimized for the new resonant frequencies generated by the modified rotating assembly. Or something like that \:D

In other words - his thoughts are to get something that damps out frequencies that are reasonably close to what the motor had when stock - if you have a lightened things up - find one with a higher natural frequency - if you have gone with a heavier clutch setup going into a truck from a car - look for a unit with a lower natural frequency.

If anyone has interest, he has taken the time to put his thoughts on the web related to this . . . http://www.epi-eng.com/piston_engine_technology/crankshaft_torsional_absorbers.htm


Also - if anyone ever wants to know the natural frequency of a damper, I can easily set up a test bench and conduct a sine sweep and find the resonant frequencies pretty quickly of the damper itself.