While thinking of ways to lighten an auto conversion (LS Chevy in this instance), I'd like some input on the dynamics of using a harmonic dampener to also compensate for some of the flywheel mass and still get the benefits of damping. My plan is to use a short splined shaft inserted in an adapter that is bolted to the rear of the crankshaft. The shaft will drive the propellor and be supported by a housing. The LS engine will have a stock harmonic dampener affixed to the front of the crankshaft as per factory installation. On the rear of the crank an ATI Rattler or Fluidamper would be attached to the flywheel to deal with any harmonics from the propellor. The flywheel would be lightened by appx the weight of the dampener. Most sources I have seen recommend using a somewhat heavy flywheel to help the engine run smoothly. I also don't want to add unnessesary mass to the drive. The aftermarket dampeners are designed to deal with harmonics thru all rpm ranges while the factory units usually concentrate on one rpm range. Anyone see any conflict problems surfacing if two dampeners are used?