I was wondering how many ppl are running the under drive pulley and did u feel anything at all?

 

There were several posts about the underdrive pulleys. The general consensus on our cars is it would not help much and may hurt it. Several reasons.
1. The lower pulley is also the harmonic balancer and it is never a good thing to eliminate the balancer. (The old stlye cars the pulley bolted onto the front of the balancer and were not one peice)
2. The fan and power steering is electric and the water pump is not driven off of the crank pulley, it is internal. So the only things ran by the pulleys is the airconditioner and alternator. I do not know that you want to slow those down or how much if any it would help you if you did.

The good news is GM did a pretty good job of designing the engine. The bad news is many of the things we used to do to increase mileage and performance have already been done so it is difficult to get improvements.

 

I don't know my friend I been working on cars for awhile. The eco motor is internally balanced like all newer cars. and i know the cars crank system runs mostly the airconditioner and alternator. but we all know less rotating mass to the airconditioner. frees up HP will will not gain HP with this pulley we will free up lost power.

 

OR just run a shorter belt and bypass it: Thats another option as well...

 

yes but the harmonic dampener is on the pulley. can the engine run without it...yes. will the engine lonjevity be affected.... who knows.