Nothing, other than a lighter wallet!!

 

LOL...your sorta mean.. but cool (read accurate) non the less...

 

A LT1 motor is very different from an Ecotec Motor. There are little vibrational differences between a stock pulley, and billet pulleys. Billet pulleys actually are far more balanced than the stock pulleys. Also the Ecotec has internal balance shafts. GM sells a billet crank pulley through GM performance that does not void your warranty. The crank is about $550 last I looked it up, and has zero harmonic balancing features. If GM will warranty a non-harmonic crank pulley...I see no problem in putting on a billet aluminum crank pulley. GM also has two crank pulley designs. One with a damping ring, and one with out. The new design is the one without the ring, and is also a snap fit...instead of a press on fit. Like the ones on our HHRs. both are interchangeable since they both go on the same crank shaft p/n.

Will there be greater harmonics, yes, will it effect the motor, well it has to add some wear, but how much none of us really know. I personally do not believe it adds enough to cause any major concern.

 

Thanks for the response and added information. I think I'll keep an eye on things and see if you guys start having bottom end issues after a couple years. Good find on the GM billet part though.

FWIW the LT1 is also internally balanced, the "balancer" is for absorption of harmonics and not for actually balancing the rotating assembly. In fact, on a stock LT1 the crank hub isn't even keyed.

 

I am interested in this. I will say one thing I do not know how much just lightening the pulleys will help performance or hurt durability. If it is underdriven that might be a different story as it turns the air conditionaer, alternator and anything else running off the crank at a lower RPM freeing up a little horsepower. I believe underdrive pulleys can help performance and mileage but you must be careful that you are still turning alternator and water pump fast enough to do the job. Curly

 

I have a prototype, and showed a few people it at the 2nd Annual HHR meet that was in july. I'm working on getting more dyno information, and getting them into production.

 

the thing was significantly lighter. looks great too if you are even going to see it really.