STILLEN lightweight crank pulley

370ZDreamer

You are missing the point. I've had machine shops zero balance engines I have had built in the past. This does not mean you still do not need a harmonic dampener. A rotating assembly will always have harmonics that need to be dampened.

That is great that the pulley itself is perfectly balanced. That means the pulley itself will not introduce any additional harmonics. However it does nothing to absorb the harmonics that are inherent to the rotating assembly.

As the engine turns, the changes in direction from the pistons moving up and down and the forces exerted on the crankshaft by combustion force pushing the piston/rod down on the crankshaft produce torsional vibration. The crankshaft itself being perfectly balanced as it rotates is not where the harmonics come from. Sure an out of balance crankshaft will make things worse, but once the crankshaft is balanced, the forces at work on the pistons and rods exert their own forces which produce the harmonics in all engine rotating assemblies. That is why you need a dampener to absorb those harmonics.

If you look at this picture of the engine http://www.seriouswheels.com/pics-20...-1920x1440.jpg

You can see the ring bonding the inertia ring to the inner hub. It is a dampener and it needs to be there.

The reference to the shop manual that Wstar quoted further proves my point. You want to pull the dampener off from the center hub, not the outer ring because you could break the bonding and separate the outer inertia ring from the center hub.

I am a bit surprised at something like this from Stillen as I've always held your parts in high regard, but when it comes to this part, you wont be seeing my money for it. I don't believe its right.