I had to go and find some info for my own education on Harmonic balances - this article seems to explain a lot on how they work, and what problems to look for: AGCO Automotive Repair Service - Baton Rouge, LA - Detailed Auto Topics - The Importance of The Harmonic Balancer

 

Just a hunch, but check the AC compressor.
My 2010 SS makes a very slight "WaaWaa" noise when the compressor is engaged. Mine is noticeable at about those same RPM's.
Although your's seems to be more severe than mine.

 

What happens with the harmonic balancer is the rubber goes bad between the hub and the outer ring in which case the outer ring slips. I've not ever heard that happening with a LNF but anything is possible. Also, you can't remove the balancer and run the motor since it runs the oil pump.

Good point FMG, when you had the belt off did you start it to see if the noise was still there?

 

If you take the harmonic balancer off you will likely get a code for crankshaft position sensor, that will require somebody with a computer.

I don't think our wheels have the rubber in them, I recall a solid metal one.

Can you see the engine vibrating?

Just for kicks check your flex pipe! I have heard that description before.

 

You could also check the bolts for the torque converter.
When rotating the engine, make sure to turn the crankshaft boltclockwise only.

 

Crankshaft position sensors is located near the back of the block. The reluctor is screwed to the last counterweight on the rear of the crank.

Don't know for sure if ours are solid or not, will look at the one I have on my cart tonight.

 

Had a similar issue with two separate vehicles of mine years ago.

One turned out to be a cracked flex plate, the other was a missing flex-plate to torque converter bolt.

 

I just know the "book" says it needs to be relearned (needs a good computer or Tech2) if you R&R the harmonic balancer. You may or may not get a CEL, if you do that's probably why.

 

Roger that, thanks

 

Ok , so much good feedback , I did not start the car when the belt was off , I was thinking of doing it but was not sure of it was ok . I can try that tonight . And you can't see the motor vibrate , it doesn't shake , but you can feel and hear the vibration . At 2K RPM it"s very noticeable , the higher the RPM the faster the WAWAWAWA. And I'll check the flex pipe and torque converter area as well. Good article on harmonic balancers , now it's even more suspect , For the time being I'll closely inspect the harmonic balancer without removal and tighten to see if it's loose . Thanks everyone