Doesnt matter what you do to the pulley, the tunes that are flashed still command the same AF ratio. Leaning up the tune by a smaller pulley is just going past what the injectors can handle for fuel, thus leading to a leaner afr. The ecm is still commanding the same fuel. The stage 2 pulley just gains that extra HP by the extra boost allowed, the afr is still the same commanded. Both tunes are identical, the only diff. I have seen in any tunes is the 07 model year ss/sc is a little different from the 05-06's

 

you can lean up the tune with a smaller pulley because you are pushing more air into the engine. The tune will compensate for the extra air, and push those injectors to there limits. Obviously, you do not want to go to rich at some point.

sorry, to lean

 

The only leaning going on with a smaller pulley is when the injectors can't supply enough fuel for the commanded afr.

 

not true. you can run lean without maxing out the injectors.

 

Just so everyone knows, a tune is going to keep commanding the same AFR no matter what pulley is on. The only thing that is going to happen is you will get real lean way up top and your IDC will go through the roof. I am not saying a 2.9 on S2 or S1 is bad, I run this same setup. I am just trying to let people know that a pulley is not going to change your tune very much if at all.

Area47 can explain it better.

 

it wont change your tune, but your tune will change what is needed.

 

Please explain . How would the stock stage II tune, that is set at a certain AFR, is going to run lean if the injectors aren't over 100% IDC ? Of course you can be tuned to run leaner , but the stage flash is going to try and keep the same AFR no matter what pulley you are running .

What your tune changes is the amount of fuel it needs to keep it's commanded AFR cause you are forcing more air into the motor . When it can't supply enough fuel (maxed injector's ) then the AFR will lean up .

 

Well they couldn't get to my car yesterday which sucked so he told me to bring it in this morning well the tech that was gonna work on it had another customer helping him intall crap on his new truck so that took till 11:30. But he has the injectors in, now he went to lunch lol. So just waiting on the tune. Man why is it when u really want something it takes forever to get. ugh. Also saw that my tire is low again. probably gonna need patched and just having my wheels painted scares the crap outta me when they take off the tire.

 

my point. when you run a smaller pulley than a stage 2, you will lean up the tune because you are probably going to max out the injectors. If you use a 2.8 on a stage 2 tune, you will lean up (especially in colder weather where the air is more dense). You are just asking for trouble. I think the 2.9 pulley would be the safest I would go especially living in MN. Other than that, you will need bigger injectors.