ok so i've always ran gm stage 2 and i put on every now and then my 2.8" pully and it either boost 17 to 20 pounds....well i was tired of being even with my friends cobalt so i decided to put it back on and also cause it's nice out... well i put it on . jump on the high way and get on it. and what do you know, for some reason it boosting exactly the same as stage 2. 15 psi. i have not changed or done anything and i have already ran this setup once. does anyone have any idea why it would be doing this? help.

 

if your running a 2.8 with stage 2 42's injectors your dumb

 

17-20 on 2.8 is wrong.... have you got exhaust or anything since those "17-20" # of boost? Also are you getting a tune everytime you change your pulley?

Also.... Boost does not = power. Does the power feel the same?

 

no like i said i have not changed anything.....and it normally boost 18psi and when it was a cooler night it would do 20....it just doesn't make any sense....and yes it is fine with the 2.8 when i put it on before i did all the calculations and i was not maxing them out....not even close enough to consider upping.....
but to answer yours question it seems like it boosts to 15 psi faster but just stops increasing around 5000 or somewhere around there. very awkward ....the only think i can think is that after a certain point that it's leaking boost somewhere......

 

you did the calculations? people like this make me lol, Im not even gonna try and help you, have fun with your injectors going static or have a 5k rev limiter

 

frew you do realize there are alot of people that have ran 2.8 pulleys on 42s right?

 

ya, there are also alot of people jumping off bridges too, I just dont think people know the associate risk they are taking, this is what I refer to when modding irresponsibly, why not just spend the extra money and be safe and not have to worry about this problem? These injectors are unpredictable I have seen people with the same mods run completely different IDC, on average the IDC is mid-high 90's, thats an average on a 2.8. I have seens others as high as 115% IDC, play it say spend the extra money to keep your car safe and sound, your number 4 cylinder will thank you.

 

first off frew i've ran ran that setup for 2 years straight without a problem at about only 78% usage and when you hit 80 to 81 is when you start pushing them. and yeah i tried doing it the safe way after the 2 years so i bought 60's and had it tuned and a month later it blew the motor and on the new motor its running at exactly the same idc's and i think if i can run it for 2 years without a single problem you should think again.....

so there again can anyone help with this problem is there any known boost leaks or anything that would cause this ...im not getting belt slippage or anything like that..???

 

then whoever did the 60's tune doesnt know what their doing, our stock boost gauges are pretty inaccurate, best way to see what you boosting max is go logging with hptuners and do a couple pulls, superchargers have very few places where they can have a "boost leak" m62-to lower intake manifold-to head, that is all.

 

IM nipple, MAP sensor, BPV, BPV/pressure sensor T, boost gauge Pressure sensor, Injector seats to head, Injector seats to injectors, and, of course, all the hoses that connect everything are just a few of the leak points that you failed to mention.

 

Cliff Notes (common answers to questions):

What comes with a GM Stage kit ?:

-GM Stage 1 = 42 lb/hr injectors & tune
-GM Stage 2 = 77.9mm pulley, hub, shorter belt, 42 lb/hr injectors, & tune (same as GM Stage 1 tune)
-GM Stage 3 = 76mm pulley, new pcm/tune, dual pass endplate, & uses injectors from GM Stage 1/2.

Are GM Stage kits covered under warrenty ?:

-GM Stage 1/2 are covered under warrenty. GM Stage 3 is for off road use only (no warrenty).

How much boost do the GM Stage kits make ?:

-GM Stage 1 = 12.5psi (same as stock)
-GM Stage 2 = 15psi (on avg.)
-GM Stage 3 = 15.5-16psi

How much horsepower do the GM Stage kits produce ?:

-GM Stage 1 = 236hp & 205tq
-GM Stage 2 = 241hp & 218tq
-GM Stage 3 = 248hp & 260hp w/ 100 octane


2.8 is way too small for 42s. 60s should be used for a 2.8. You must've had a terrible tune if blew the motor when you swapped to the 60s. That's not the 60s fault. That's the tuner's fault.

The chart is referenced here;

https://www.cobaltss.net/forums/show...ge#post4739210



By the way Kyle, I think I know you.

 

this a typical thread here

 

lol who are you backdrift...... and is the gm stage 3 the same as a 2.8......and what would be the best way to look for a leak let run and spray ....something there and see if it sucks it in?

 

Start the car, and spray each connection with a half second shot of starter fluid. If you hear/see any change in the engine's idle, you've found your leak path.

 

You work at Ganley right? And you have a friend who calls you Biff all the time? If not, then ignore me.

Any ways, the Stage 3 Pulley is 76mm which is 3in if I'm correct, but a 2.8 should be safe to run 60s.

 

2.992" if you want to get nutty about it, haha. Most people call it a 2.99". 2.99"/3.00" pretty much the same thing. 2.8" is very safe a 60's and a good tune. You can run a 2.8" on 42's, but you need to be tuned for it. Do not put a 2.8" on a GM Stage tune.

 

2.99212598 inches

But I can round up real good.

 

yeah beef it's me and ive been running that pulley on mine and i am running the stage 2 tune. and thanks Illini_06SS for the help. i will try that out.

 

psh, poppycock lol

 

I only know that because I became intimately familiar with all of the leak paths on mine while trying to find the cause of my P0170/Lean idle... Turns out the little rubber nipple for my autometer boost gauge didn't even survive 6 months before starting to disintigrate and when I tried to pull the boost line hose out of it, it tore into two pieces...

 

Yay!

 

Possibilities:

1. boost leak
2. bad boost gauge (i can tell you a long story about an evo with a bad gauge and how it almost ruined it)
3. Belt Slip

Corresponding Forward Action:
1. starter fluid trick
2. get/borrow another boost gauge & compare
3. confirm belt tension, belt condition

 

Dirty is correct in all of what he said. Not sure if you're using the Stage2 Belt or the tensioner. Make sure the tensioner isn't loose causing belt slip or anything (although I feel like it would be worse than boost problems if that were the case).

Also, are you still running the stock DP? The Stock DP pinches to 2.0in at the 02 sensor, and the over-the-axel pipe is on 2.25, so you're not 2.5 all the way through it that's the case. This could be causing the problem as well.

 

well i think it could be possible its a vacumm leak after so much boost...but the boost gauge is fine because i also have the aeroforce interceptor scan gauge and it is reading the same...... belt has tension trust me....it was a bitch to put the belt over the pulley when i changed it ...im running all the same exhaust as i was before( i have replaced flex pipe but same as last and i have the gm cat back...

 

there is no solvent/oil/brake fluid or anything causing it to slip even though its got tension?

just rattling off ideas