Hi guys, like the title said, I wondering if it safe to run a 2.9 pulley with the GM stage 2 kit ? It must stay really safe... so, any opinions?

Thanks, Fred

 

If you want it to be really safe, then no. Your idc's will be through the roof meaning your injectors will be maxed and then some.

 

Should be fine, but to be safe run a 3.0.

 

Gm stage 2 pulley size is ? 3.0 ?

 

Im running a Gm stage 2 and a 2.9 pulley and have no problems at all. I also have a ZZP heat exchanger upgrade and temps are low.

 

Yup.

 

It's not worth it because if you heat up and boost more you'll prob end up pulling timing and w/e.
Take the 50 for the 2.9 and put it towards a 3.0 and custom tune, trust me you can get a good thing going with 3.0 and 42's .

 

what are your iat2 temps on a 90 degree humid day? just curious cuz i had the stg 2 tune with my 2.9 for a while

 

Hard to take a decision.. some say its great, and other say its not recommended... I think that I'll keep my 3.0 pulley...

Guys with 2.9 pulley on stage 2, did you really noticed a difference over the 3.0 ?

 

i say go for it, a lot of people run the 2.9 on stoc stgII tune, the stgII is tuned to rich anyway, should be fine...although dual pass and a second h/e will help your cooling aswell

 

I'll check it out...

 

stage 2 pulley size is 3.065. through personal experience i would vote no. my car was LEAN on the low end. if you drop to a 2.9, find a dyno that can rear air/fuel, and make sure you're safe. people tend to only look at the injector flow rates and not the air/fuel ratio.

one thing to note is, there are people who will swear its safe and have proof, while there will be others (like me) who say don't do it. every car is a little different and will take to mods differently. you can either play it really safe (keep the stage 2 pulley), somewhat safe (throw the 2.9 on and do a dyno run to check everything out), or be really dangerous and just do it and not look back. lol. i chose the 3rd route and luckily i did my tune a lot sooner than originally planned.

btw, i didn't notice really any difference. boost picked up slightly sooner, but i didn't have any cooling, so i really didn't feel a power difference. at times felt slower than stage 2.

 

I have an Interceptor gauge and a A/F gauge to install before. But you're right. If I have to do it, I'll be sure before that everything is perfect... Like I said before, I really want to stay safe.

Someone already installed an Interceptor gauge on cobalt's ? I bought it before for my GTP and I read on the Aeroforce website that it needed 3 wires to make run the gauge but mine only have the red one, with my obdII plug of course, Is it will work all the same? On wich power source could I plug the red wire?

Thanks, Fred

 

If you want more power out of your car simply get retuned instead of dropping pulley sizes.

 

I don't know, I went from a 3.0 pulley to 2.9 pulley and my A/F went up about .5 or so at WOT so I needed a new tune. I don't think I'd feel safe going all the way from 3.065 to 2.9, but that is just me. Your injectors aren't going to be maxxed out on a 2.9 pulley. Mine are at 76% so all is well. Obviously elevation could play an important role.

 

Elevation and air to fuel ratio play a big role into it, I have seen a lot of 42lbers being maxed out on a 2.9 pulley but it just depends on what afr they are running.

 

What can your injector duty cycle being at 140% lead to in the long run?

My uhh.. Friend has that

 

At 140% IDC he would have had to see the A/F ratio was not ideal.

 

Ok.. But lets say the car runs at 140%... What is the problem that it will lead to in the long run exactly?

 

boooooom.

 

****

 

hahaha

 

i have stage 2 with 2.9 and 42lb injectors and i have no problem wat so ever runs and pulls fine

 

I had to laugh at this as well, lol.

 

My IDC's were at 122% @7K rpm. I ran GM Stage 2 on 2.9 for over 2 years with no issues at all. But the injectors are considered 'maxed out' at 80%. So maybe that will give you an idea on how hard the injectors are working if they're at 120%+.