I have read so much about people running the gm stage2 tune and wondering how safe it is to run with the 2.9 and 42's. Well it seems to be split down the middle. Some say yes its ok, some say no you are taking a risk. Never the less. I have a gm stage2 tune and a NOT installed as of yet 2.9" nates pulley. How ever. Lately i have been wondering if it would be a better idea to just get smooth flow to make me a 2.99" ( gm stage 3 size ) pulley instead of running the 2.9". My main reason for this concern is there are no tuners any where close to me at all.

So if i went with the 2.99 , gm even says in there faq that it is safe to run that pulley on the stg2 tune. Is there any gain in power to be felt worth while or not ??

Thanks for the input !

 

i am running a 2.9 with stage 2 and have not had any problems at all. and there is a little power increase. IMO 2.9 is a good size because the STG2 tune is very rich to begin with. but i would not go any lower due to IDCs being almost maxed. although some ppl have gone to a 2.8 on STG2 tune

 

Been running the ZZP 2.9 on GMS2/S3 tune for 3years and did a compresion test the other day . 190 across all thre cylinders. 2.8 is the one you don't want to do.

Performance wise the supercharger creates boost quicker

 

Well it would save me from buying another pulley sense i already have the 2.9". Does anyone know what there af ratio on a 2.9 and stg2 tune ?

 

I have had the 2.9" pulley on the GMS2 tune for over a year now with no major problems. Just watch how hard you push it because the 42lb injectors max out up top with that pulley. Personally, I'm putting on a 2.7" with 60's and a custom tune soon because it'll be safer overall (IMO).

 

Thats what scares me alittle is the injectors going static uptop ! I dont wanna blow the ol girl up !! And it gets cold here in Canada in the winter ! Like freakin -30 somtimes. Getting a 2.8 and 60's doesn't ever seem like an option for me because of how far away the nearest tuner is. Like half way into the next province.

 

Yea Canada ftl on that one. Honestly I don't think it's worth spending the money and time to swap to a 2.99 pulley because the gains you get wont be a whole lot. You'd probably only notice a difference on the dyno sheet. If it were me I would just drop to a 2.7 or 2.8 with 60's and try to find somewhere to get dyno/tuned. Just sucks that there aren't any places up by you that do it.

 

unless you can get a good tune, leave it the way it is. you wont see much from a smaller pulley with the crap s2 tune.

 

what about getting a tuned ecu from say ottp that is tuned for the 2.9 and 60's ? Do they even do that byitself or just in there kits ?

 

I ran my car stage 3 with 2.9 pulley for a few months to keep it close to stock so I could trade it in and it ran great! Best setup tho was 60's 2.6 tuned for meth!

 

i thought u were getting the TVS?

 

i thought u were getting the TVS?

i thought you were getting the tvs?

damn it, computer sucks ass

 

I'm in Canada too, Quebec and with my GM Stage 2 and stock stage 2 pulley + R.A.W. intake, my IDC are already maxed out at 6200-6500 RPM. I guess that it depends of the car you have, I certainly would not put a smaller pulley in there! But anyway, soon I'm gonna have the 2.7" pulley, 60 lbs injectors and the OTT tune + every known cooling mods (excepth meth) + all full exhaust.

 

I ran the 2007 gm tune (leanest one, commands a 10.8:1 still pig rich AFR) with my old 2.9 for a year with no problems. My afrs were actually really rich. Even with the 2.9 I was running 10.5:1. I would do it if I were you.

 

if i was to run a 2.9 with 60lb injectors and a custom tune would i be ok. or would i be maxing out something?

 

i ran the 2.9 on the stage 2 tune with intake and full exhaust. before i got tuned we did a base run. car was VERY lean on the low end, rich on the high end. my tuner, who is big with the ecotec's, i trust his judgment, said i would have run into problems it was so lean on the low end. so it's not just about the fuel injectors maxing out, it's also how air/fuel mixture. if you're unsure, get dyno'ed where they can check your air/fuel ratio, cause i was running VERY lean. also, i didn't notice any power increase, i think due to how lean the car was running. in some cases, especially with the added heat, the car actually felt like the pickup was worse. i'd either stay with the stage 2 pulley, or get a pulley from smoothflow the same size as a stage 3 pulley (2.99").

sssc4life, i'm running a 2.75" on 60's and a custom tune and everything's fine. a 2.9 is a pretty good pulley to run with no cooling mods. anything lower, i'd seriously start looking into cooling, especially a dual pass end plate. i'm running a dual pass and a heat exchanger, and my intake temps are really good. highest they got was my final pull for the tune, hit 120.

 

leave it how u got it or upgrade with proper tuning... youll be going lean the whole time

 

so 60lb and 2.9 pulley sounds good to you ??

doesnt any pulley smaller than 2.8 max out the supercharger and its hard on it ??

 

i've heard the 2.8 will overspin the blower around 7100 engine rpm, so as long as you keep the limiter at 7k, you'll be good. with my 2.75, i'm probably maxing it out around 6900rpm, which isn't too big of a deal. one thing that made me go with the 2.75, and is even making me slightly consider a 2.6, how often do you run your car up to the limiter? 8 times out of 10, i'm shifting at 5k, if i need to get going, i run it to maybe 5800-6k. only once in a blue moon do i take the car close to the limiter, so i'm not doing any damage over spinning. if you're always going up to the limiter, or want to raise the limiter, a 2.8 and 2.9 will both be safe.

the big thing you need to consider when dropping pulley sizes is cooling. the stock cooling system works... when the car's stock. gm recommends the dual pass endplate on a car with stage 2. the dual pass helps a ton. anything below a 2.8, i'd want a heat exchanger as well.

 

I see your point, but think about this. If your shifting at 6k with a 2.75 and he is reving to 7k or more with a 2.9, he is making use of the entire powerband. You may have your torque but he is gonna keep pulling right past you while holding it out longer. Gearing is a big helping factor when it comes to our cars and it kind of defeats the purpose of our gear ratio to not be able to rev it out all the way.

Not bashing you, just stating some food for thought. If I were the OP I would stay with the 2.9, rev to what you want and not have to limp the car in the high rpm's.

 

thats why i didn't go crazy low with the pulley. i know i can safely rev up to 6800, and i know 7k won't be over spinning my blower too badly, so i don't really see it being a problem. because that's a pretty good point. the only time i typically get up to and over 6500rpm is if i'm running with someone, or i REALLY need to get the car going. lol.

my torque starts to drop off just after 5k, my horse power builds till right around 6600rpm where it levels off. at that point, it's pretty pointless to keep going in that great, after passing 6600.

 

2.9 is perfectly fine on the S2 tune I ran a 2.85 for a short time with the S2 tune and had no issues.

 

Well there is deffinetly some difference of opinions on this topic. I deffinitly don't wanna hurt the motor by running to lean. As of today, its starting to sound like my flex section on my exhaust is leaking !! And the damn cat and all is only a year and a half old !! I still cant decide what to do ?

 

I would just say since you have the 2.9 make it easy on yourself and put that on. No use in getting a different pulley when you have one that will work just fine.

 

Id leave it until you get 60s. I had a GM 2.9 on 42s and I ran out of injector and got super lean around 5,500 rpms and above. Went to 60s and I was fine.