Originally Posted by kitabel (Post 9764792)

1. The absolute weight difference shown on the scale is nearly meaningless.
2. The reduced diameter of the crank pulley, and (most important) reduced weight at the rim of all pulleys is far more important. The inertial saving is far more than the weight difference.
3. The speed of the accessory drive will be reduced in direction proportion to the ratio between the old damper OD and the replacement; your alternator, power steering and whatever is driven off that belt will run slower and consume less power.
4. If the alternator is in that belt your charging rate will go down; if it's really slow it won't charge at idle when the lights are on.
5. You no longer have a harmonic damper; no engines have been built without one for about 60 years. They didn't build this in to the replacement because it costs lots of money, not because you don't need it. What does it do? It prevents (at least reduces) destructive torsional vibration from wrecking your crankshaft. How to deal with this: it may show up as extra vibration, "buzziness" in the steering wheel, shift lever, pedals etc. at certain RPM regardless of gear ratio or throttle opening - keep away from those. Drive through them, but not in them continuously. Raising your speed by only a few mph makes you safe.