i want to know if i can run 2.9 pulley with stock belt and stock tensioner?
thanks

 

Your gonna want the stage 2 belt, it'll be a tight fit

 

You will need a GMS2 belt.

it will slip on with the stock belt.

 

Or just buy the adjustable tensioner and done with it.

 

With a stage 2 belt I have had my 2.8in pulley slip, do not remember if it ever did on a 2.9. I recommend you get adjustable tensioner though. A sudden drop in boost during a pull because of slip does not make a happy motor. Plus you can set your self up for good tension on any possible future setup, stock, 42s on a 3.0-3.1, 60s on a 2.8-2.9, 80s+E85 on 2.7, TVS etc.

 

The S2 belt is good down to a 2.7 w/o issue.... If you had slip, it was more than likely due to the aftermarket pulleys ribs.

I've always noticed smoothflow, and other aftermarket pulleys do not match the stock/gm pulley rib dimensions.

 

Stage 2 belt and OEM tensioner.
2.7 pulley all day on that set up.

 

Never thought about the pulley ribs, guess it's safe to go adjustable tensioner for the extra tension though.

 

Safe?

It is not needed.

 

I have had my belt slip during a pull before so I'm trying to keep that from happening again.

 

Spend the money on a new belt then instead of tightening an old one.

 

Belts only about 9months old, it may be possible something else is going on. I am going to check the tensioner pulley bearing to make sure it isn't worn out and causing resistance. Belt has been good for about 2 weeks though so I might just leave it be.

 

I would check all of the pullies then.

I had a 2.7 on mine and made 279whp; never had a slip issue once. Smooth flow pulley. A good belt and smooth pullies are essential.

 

I will, Thanks! Btw, 279whp is pretty impressive, were you using meth or E?