Since the Stage II tune tends to run rich, would I be ok dropping it to a 2.8" pulley without a tune and the Stage II injectors. I have the pulley, but I don't have the money right now for the 60lbs and a new tune.

 

Search button is your friend. This topic has been discussed ad nasium. In short... no.

 

i'm sure you could live with it for a while, there are plenty of guys on 2.8" pullies and stage II injectors (42lb injectors) and tune. Most people would recommend you ditch it and get a 2.9" to be safe.

 

I have had mine like that for 1 1/2 years and its been fine.

 

I have the stage 2 with 2.8 pulley for almost a year now, no problems, car runs strong!

 

just run the 2.9, its safer. unless you have HPT so you can see what you IDC's are

 

I debated going to the 2.8, but after researching on here, I decided the 2.9 was the wiser choice; being on the safe side of the envelope.

 

Your running meth thou right?

Have you logged your IDC? I'd like to see what they are in the higher RPM ranges. My guess is pissed.

 

2.85 And 2.9 make your damn idc almost the same ****, ive logged on both and the **** dont change boost is the same iat2 is the same idc is the same no damn difference. I dont know about a true 2.8 though

 

changing your pully doesnt change your AFR.
the car will still try and run rich even with the 2.8 on, which is why the injectors have fits.
S2 running rich doesnt mean its safe to just throw a smaller pully on.

 

^^ bingo

 

Wow your new here and get it. There are some that have been here forever that haven't figured that out yet lol.

So what are they ? Are you running a stage tune?

 

wait for the 60#ers man. better safe than sorry, right?

 

I would go with the 2.9 and still get tuned.

 

i here some people getting a stage 1 and dropping a 2.9 in. is gm s1 and s2 the same tune? isn;t the only difference is that gm s2 just has the smaller pulley and belt?

 

Bingo x384394839

 

and bingo x230493453

Same tune, just smaller pulley/belt. If you plan on downgrading pulleys, no real reason for s2. Just buy s1 and the pulley and belt later when you decide to go smaller.

And as people are saying, smaller pulley doesn't increase AFR. AFR attempts to stay the same as it is a direct function of your tune. It simply says, instead of getting X amount of air and needing X*Y amount of fuel, we are getting X+Z amount of air (Z being the increased airflow from the smaller pulley) and now need (X+Z)*Y amount of fuel. The reason people's AFR goes up is because sometimes, (X+Z)*Y amount of fuel is more than the injectors can put out. If they can only put out a certain amount, and that is amount is LESS than (X+Z)*Y (what your tune is asking for) then you still have X+Z air, but < (X+Z)*Y fuel which in turn is an increase in AFR. This method of leaning out your tune is hell on the injectors because they will be forced to run at 100% capacity for extended periods of time while even this 100% output is less than requested for your tune, hence why people say you should upgrade injectors when going below a 2.9.

If this is erroneous, plz correct me, but this is my understanding.

 

Although I corrected a couple math-related errors, your logic is otherwise sound! Good info for fresh-on-the-scene forced induction modders!

 

2 years here.

I dunno why but if you look at all the blown LSJ they all have 60# injectors..

 

not all the blown cars had 60's...I know of 4 that had 42's.

having said that, its about the driver...

 

^^ hm he may be on to something...

 

Ahh yes, because fuel is a function of air intake. Thanks for the little correction, and I edited my post for future references. Appreciate it

 

having 60lb injectors also means having custom tuning.....
injectors are just injectors.
they just do what their told.