After seeing a bunch of people on here running a 2.9 in pulley it has really caught my interest. I have a gm stage 2. Is it really worth using a 2.9in pulley?]

I guess the big question is, is there a big benefit from running a 2.9 on a stage 2 setup? With the 42lb injectors, stage 2 belt and tune?

 

very little gain will be produced, but some will be noticed....

you will notice more with a tune...

 

is it noticeable to the point where you feel the gains? Also do any of the pulleys mount to the stage2 hub?

 

I think most of the pulley makers make pulleys for the GM hub. Do a search for Nate's pulley. I have the 2.9 on GM stage 2 tune and no issues. 16 psi and runs good.

 

2.9 is borderline with the gm s2 tune....

2.8 only if you custom tune it.

 

^^^ Ill agree with that.

 

You can run the 2.9 just fine, but heatsoak will become an issue with no cooling mods. With winter upon us I guess it would be ok.

 

Many people are running a 2.9 on the Stage 2 tune which is quite rich with no problems. I don't suggest going lower unless you're getting a custom tune.

Oh yea, I'm Nate

 

Yeah, GM stage tune is rich and pretty much has the injectors maxed as is. Throw on a 2.9 and it will just max them out more because it's tuned for a certain AFR. Though I had a Nates 2.9 on 42's for a while without a problem.

 

yeah the stage tune commands 10.8afr, im on a 2.9 with IDC's at 122%

 

Question, making sure I do understand all of this correctly....I'm running the same thing he wants. GM Stage 2 plus 2.9. Now, with the GM stage 2, my injectors are at ~100 duty cycle. But that is because the GM Stage 2 tune runs rich, right? If so, that means I can go out and lean the car up a bit with HP tuners which will drop my injector duty cycle to, we'll say as an example 90 percent. Make sense?

I just wanna make sure I am understanding this right. Because I used to be under the assumption that with or without a tune, 42's were going to be way past injector duty cycle.

 

you really dont want injector duty cycle to be over 80%. they are basically just along for the ride after that going static. my car runs strong though

 

Yea....Well, after all my cooling mods I was contemplating going up to 60's and maybe a 2.8. Not really sure if there will be a noticeable difference between a 2.9 or 2.8 with 60's and a tune. I would also like to somewhat prolong the life of my supercharger....lol

 

you'll be fine on the 60's and 2.8. lol. i believe a 2.7 is the limit before overspinning the blower so you'll be good. you will see a pretty big difference if the tune is good, just remember its all in the tune

 

truth

 

i don't think small mods are really noticeable on the 2.0. anyone that can put on an intake, exhaust, one size smaller pully, etc. that thinks they can feel the difference between 240 whp and 244 whp has one hell of an acurate butt dyno.

 

when i went from a 3.0 to a 2.8 i checked my logs and it was almost identical the increase.

 

Well, when I get to that point I'll let you know and we can drive down to Miami for a tune day or something. Meet half way cause I have had 0 luck finding someone here....lol

 

if your not 100% sure just go with the stage3 pully its a 2.99 thats what i use now and with no tune. i have had no problems, i hit 16psi

 

i just put on my 2.9 from nate and i like it a lot, but im hitting like 15 psi? which i think its because i have a larger throttle body i ported my inlet side of the supercharger, and i have a catback. because before the 2.9 i was only seeing like 12.5. we will see this week when i get my interceptor. and if you swap pulleys good luck with those blue screws mine were rediculous!!!!!