I ran a GM stage 3 pulley 2.99 just to be safe, I felt a true 2.90 was too much on the injectors . Going from the stg2 3.06 to 2.99 isn't huge but it was noticable. The car would boost quicker at low RPM as well as giving it 1-1.5 PSI by 7K .

Gm stated it was safe to run on the 42 lber's in the stage 3 FAQ .....i didn't have any issues in the 3 years i ran it. People will say it's not worth it or a waste but i bet none of them have tried it for themselves .

 

i did try it for myself. was unsafe in my case, tested on a dyno by an experienced tuner/mechanic. which is why i suggest, if you want to try it, check things out on a dyno.

 

i just went to a 2.9 today with 42,s. while logging my injector duty cycle was at 105% at 6700 when i hit a fuel cut..

 

Those IDC's seem low. Are you tuned? That would make sense because GM Stage 2 is like a 10.0 AFR. If it has been leaned out to 11.6 or so I could see why your IDC's are that much lower.

 

A 2.99 stage 3 pulley ? or a true 2.9?


I was fine on a 2.99 ,but maybe it's because I'm at 1500ft and your at sea level?

 

im at sea level and i personally maxed out my 42s on a 2.9 at about 5,500 rpms. Upgraded to 60s and was fine.

 

i did the same as you, and i fully agree with your statement !! my car has been running excellent on the GM Stage 3 pulley.

 

This is also the route im going to follow as well to be on the safer side of things. A just feel that a true 2.9" pulley will be to hard on the 42's. I'm also going to install a dual pass end plate to go along with my second heat exchanger.

 

i had an actual 2.9 on, not a stage 3 2.99. i did a baseline dyno run before i got tuned with 60's, a 2.75, and cooling, and on the stage 2 tune, the 2.9 was not safe on my car, way too lean on the low end.

 

Ahh... I was talking about a 2.99 . I didn't go with a true 2.9 because i felt it was unsafe. I think we got our pulley's mixed up. I was advising against 2.9's with 42's .

 

hmm...weird i wondering why u guys cars are maxing out on 2.9's, i could see elevations being why, but people in diffrence ends of the country are maxxing...here there is a trifecta tuned 2.2sc on 2.8" running 42's at 86%idc's, mine is on a 3.0 and it @84%...both our a/f's are pretty perfect...11.5-12...

 

Yeah, that is weird. My 2.2 is at 76% on the 2.9 pulley.

 

been on a 2.9 with stg2 for over a year now. occasional WOT blasts and variety of weather. Motor hasn't even as much as pulled an engine light.........

 

GM stage Tunes........That should explain it lol/

 

No Stage 2 tune for a 2009 Pontiac G5 GT man... Trifecta tuned.

 

I was responding to the question of why other people have high IDC's compared to the 2.2 guys..........It's cause of the GM stage tune others are running lol.

 

Oh yeah, I totally agree on that one

 

To summarize guys, should I go with 2.99, stage 3 pulley, and cooling mods or stay stage II ?

 

2.99 and a second heat exchanger !

 

screw the second heat exchanger, just replace the stock one

thats because it wouldnt pull an engine light, it would just start running lean up top and cutting out.

 

What is the best remplacement heat exchanger can I put on ? The ZZP's one ?

 

Most argue OTTP or ZZP and I used the ZZP.

 

You also put the "option B" or only the heat exchanger itself ?

 

ull be fine..... i see ppl do stg2 tune with 2.8 all day... no prob....

 

i'd get a dual pass endplate before a replacement OR second heat exchanger. it's my understanding the endplate alone helps out a lot. with a 2.75" pulley, and both a 2nd heat exchanger and dual pass endplate, my intake temps, on the 5th dyno pull, were 120. cooling mods are underrated and often overlooked with forced induction cars. get the 2.99 and a dual pass!