dont feel like bringing back old threads. so i started my own. i currently have a gm stage 2. i want to go to a 2.9 infact i am. i got the auto light plugs to install. and i already have a cai and exhaust. so how long can i run a stage 2 tune with a 2.9 and how safe is it. and what am i looking at hp wise and boost wise? not really worried about track times thanks guys

 

You should see around 15-16 psi boost, and with your mods maybe 230ish hp...As long as ur IDCs arent over 100 u should be ok, but ive heard u dont wanna see the IDC get over 90

 

You may not be worried about track times and only thinking about hp and boost, however what you should be thinking about is IDC's.

IDC = Injector Duty Cycle. The stage 2 injectors were NOT made to handle a 2.9 inch pulley. I have personally seen 2.9s running over 120% idc's on the stage 2 tune.

I have said it once and I will say it again, it is NOT safe to run a 2.9 on the stage 2 tune. Grab 60lbers and run whatever pulley you want, with adequate cooling.

ALSO - without adequate cooling mods, you will heat soak faster and actually LOSE power. AND you will be LOSING power because you will not be getting enough fuel in the top end.

The general rule of thumb I use when tuning is to keep IDC's below 80%. A lot of people use that rule, 90 is fairly high imo. Anyways, the stock stage 2 tune with a 2.9 will gain you around 16lbs of boost give or take, all depends on the rpms, and the hp depends on the dyno.

BUT I again will recommend NOT running this pulley on the stage 2 tune. Many people do it and don't have problems, and MANY people have static injectors that aren't giving there motors enough fuel on the higher rpms.

 

Over 3 years with Stg 2 and a 2.9 and still running real strong

 

I have had my 2.9 with stage 2 tune for about a year and a half and have had no problems. However, I also rarely run it to redline or past 5k rpms for that matter. Maybe a couple times a month. And when the weather gets cold, it rarely sees over 4k rpms. Ya, I drive like a girl I guess.

 

I never redline. But will get close alot. Have y'all dynoed? Also I personally say 2 06 get dynoed. Both cai and exhaust car number one had a trq damapner and 87octain. Max up was 208. Car number 2 had 93 max up is 233. I was like how is that so but it was true.

 

I was just on Cobalt Addiction and I was checking out their stage packages and they have their stage 2 kit set up like this, I am copying and pasting what they have.

Stage #2PLUS : 2.8 ZZP Interchangeable Pulley system , 1 step colder ngk spark plugs , GM shortened belt , 42# Lucas Injectors , Injector Wiring harness , Stage #2 Retune ... Est. 55 Hp over stock - 16.5 psi boost

so they have the 2.8 pulley on the 42# injectors. and there u can see the increase in boost and hp as well.

 

YOu will be fine with the stage 2 injectors and a 2.9, but the tune.. eh. You should get a custom tune for that pulley size if you really want to see the true gains you can get from it.

 

A lot of the IDC problems from the GM Stage 2/2.9" pulley come from the stupid rich tune. Leaning it out into low/mid 11's will drop the IDCs a lot. Also, if you live somewhere warm or high you will be safer then somewhere cold or low (or both!).

 

Alabama. Coldest so far has been 32 LOL. We have alot of hills

 

Low meaning not to high above sea level bro. Hills won't make much difference.

 

2.9 on a gm tune is fine.

 

Everyone that is posting about running a 2.9 on Stage 2 tune and saying they are running strong has no backing to that...Like Zach said you aren't getting enough fuel up top.. but you prolly wont realize it until you get 60s...I have a 2.9 on stage 2 tune but it will only be on for a week or two more....Do you'll even realize that IDC in the 100s is not good at all?? lol

 

I have stage 2+2.9 and I have had no problems YET. I will be getting a tune soon, or atleast take a peak at my IDC to see if im running unsafe.

The main reason I am replying to this post is because of how ridiculously damn funny phantomSS sig is! holy **** that is hilarious!

 

i have a custom tune. getting 11.7afr at redline with a 2.9 and the 42#injectors. I see around 99 to 101 Injector Duty Cycle. Therefore I would have to agree that even with a 2.9, 60# injectors would be prefered. Yes you can run them. Are you being truly safe...not really. Keep in mind that i'm seeing those numbers on my IDC with the stock exhaust and downpipe. Those with aftermarket dp's will flow a bit more and will probably jump up the idc's a bit more.

if you decide to run meth injection than you can probably make your injectors happy enuf...

 

I run 2.8 with meth n get 85%

Before meth it was 96% 7000 rpm

 

georgia weather vs pennsylvania weather ::shrugs::

wait...how are you doing that with a 2.8???

 

it all depends on altitude, weather, tune... To many variables to say whether it would be right for your situation or not. For all the people saying yes and no for your specific setup probably don't even know all your variables. Do it and get it tested. That is the only way to find out if the 2.9 will work with your stage 2 tune.

 

I have had the 2.9 on for a year and a half and no problems here. I do baby the car and never really push the car hard though. hopefully in the summer i will get some 60's and get a tune.