So I have a GM stage 2 kit and with the 3.07in pulley there is no weird sounds and everything is smooth. I have a 2.9in 4 bolt aluminum pulley as well that I went ahead and put on when it was warmer the other day, looking to get a tune in a couple weeks on new 60lbers so I wanted to get it on and make sure everything looked alright. Belt seemed tight (only 6000miles on stg 2 belt) and was on the AC correctly. The weird noise happens on RPMs 2500+ on 2.9 and Never on 3.07.

Could the new pulley be to lightweight or something?

I wanna figure this out before I get my 2.8 and 60s tuned so I don't damage something

 

How do you know the whine is coming from the supercharger? Is the whine constant with the throttle? For instance...after 2500 rpm and you're still on the gas and press down does the whine continue?

Anyhow, to me it just sounds completely normal. When you pulley down the supercharger spins faster which in turn sucks in more air. So you're just where the whine when you supercharger starts sucking in more air. You never noticed it before because you probably weren't spinning it fast enough.

Edit: Saw the title say WOT so, yeah it seems normal. Find some videos on youtube with cobalts that are supercharged and see if the noise sounds the same.

Try that ^^?

 

Will do, the issue that was confusing me was the fact that the whine sounds different all the way through a gear and not just at higher boost, If I am correct the SC should be spinning the same rate at 4725rpm on the 2.9 as 5000rpm on a 3.07. But it doesn't sound the same. I might try doing a comparison video when it warms up outside to get a better idea. My car sounds the same as any other cobalt on my gm stage 2 pulley, but the 2.9 makes it sound different than any 2.9 i have heard on youtube.

 

Curious if anyone else noticed large sound differences between pulley sizes. I know the whine will come in earlier but the whine actually sounds a lot different.

 

I noticed a large difference but of course that was going from stock to 2.8 lol

 

If it doesn't sound like marbles you should be ok...

I went from stock m62 to 2.9 TVS...the whine is a lot louder than before pretty much as soon as I get into it she screams.