Problems with the 2.8" pulley? - Chevy Cobalt SS Forum : Chevrolet Cobalt SS Forums
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post #1 of 19 (permalink) Old 11-15-2006, 10:09 AM Thread Starter
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Problems with the 2.8" pulley?

I am almost ready to buy a smaller pulley and I was just wondering about the people that have the 2.8" on there car already with the stage injecters are having any problems? I have just been hearing about people who say that the injecters will be running at like 112% with a 2.8 pulley. Is there any reliablitly to this claim and Is it really that bad? I mean I know its better to at least run a little rich rather then anything lean. And I dont want to get the 60 pound injectors that they have for our cars.

Also could I use the stage 2 belt with a 2.8 pulley?

2009 Turbo Cobalt SS
traded in 2005 SS/SC

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post #2 of 19 (permalink) Old 11-15-2006, 10:30 AM
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if you have the stage 2 and the 42lbs injectors, you should be fine all day long. if you try to go to a 2.7 or smaller, you would need to 60lbs'ers.
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post #3 of 19 (permalink) Old 11-15-2006, 10:30 AM
 
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First off, every car is different. The only real answer is to monitor your car with the 2.8 and see what the IDC's are Either using HPT or an Interceptor (IPW + This calc (http://www.stealth316.com/2-calc-idc.htm)).

What Altitude are you at? If your below 2500-3000ft than I would say (based on what others have seen) that Bigger injectors are required (At least 50's). If your between 2500-3500ft I would monitor the car all the time. Temperature can play a big role in this also. If your above 3500ft, the 42's should be fine. Should being the key word. Every car is different so watch what is going on and don't run an unsafe setup for very long.

Yes, the stage 2 belt works fine with the 2.8.
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post #4 of 19 (permalink) Old 11-15-2006, 09:16 PM
 
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How Small Can The Pulley Be With Out Switching The Injectors
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post #5 of 19 (permalink) Old 11-15-2006, 11:09 PM
 
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whodis mentioned this earlier on #2
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post #6 of 19 (permalink) Old 11-15-2006, 11:24 PM Thread Starter
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I see how that makes sense with the altitude and less air. If I used an HP tuner on my car with the 42 lb injecters and 2.8" would it make a difference or do the injectores just not have it in them to push it that far? Also what about a bigger fuel pump?

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traded in 2005 SS/SC

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post #7 of 19 (permalink) Old 11-16-2006, 02:41 AM
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we deff. dont need a bigger fuel pump

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mods coming REAL SOON!

RIP-2006 silver Cobalt SS/[email protected]/2.1 60ft.
mods:
intense 2.8 pulley
K&N Cold Air Intake
60lb injectors
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post #8 of 19 (permalink) Old 11-16-2006, 03:00 AM
 
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I'll try to sum up all the answers at once here...i have delt ALOT with thsi subject and many like it.

...here we go!

no we totaly dont need a new fuel pump...its good for FAR more HP then our motor is in stock config.

2nd....unless you are at some CRAZY alititude you WILL NEED larger then 42.5lb/he injecters that the stage kit gives...END OF STORY.

i have posted HPT data logs on many ocasion of my old set up wich was a 2.7 with the stage injecters..... the .10in differance between a 2.7 and 2.8 will make a VERY small differance in your IDC's if you were to compare a 2.8 and a 2.7

i saw 118%-122% IDC with a 2.7....thats in excess of 30% higher then you want to run an injecter in a "every day" car(or any car for that matter)

a rule of thumb is that you want to keep your IDC under 90%-92% range.

with it geting colder its only going to raise your IDC's becase the car will command more fuel due to the colder and denser(sp?) air....My logs were done when it was 80deg out with michigan humidity.

when our stage injecters pas the 92%-95% IDC range they go "static"...in other words the just stay open and dump fuel sence they cant keep up with the ECM command

when that happens you loose your AFR control and that can and does lead to blow LSJ's...BAD BAD BAD.

also when an injecter is ran to and past its limits offten the injecter is more prone to breaking it self...and that'll blow a motor in about 3secs....not enough time for you to react.

any time you start steping pully size down and/or you do custom tuneing its always a good idea to get a solid Wideband 02 guage and sensor so you can track your car and avoid a blow motor....they also play a HUGE roll in geting your tune "just rite" for your car.

HTH
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post #9 of 19 (permalink) Old 11-16-2006, 01:23 PM Thread Starter
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Well that pretty much sums it up like you said. what size is the stage 2 pulley? I think it is just a hir bigger then 3.0" isnt it? like 3.05 or something? So would I be safe getting maybe a 2.95 If I can find one?

2009 Turbo Cobalt SS
traded in 2005 SS/SC

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post #10 of 19 (permalink) Old 11-16-2006, 02:12 PM
 
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HMMMM... now i have to upgrade injectors... i just ordered the 'pulley boys' 2.8 pulley & they said " most people still run the stage 2 injectors, so i dont believe its neccessary" they said not to quote them on it cuz all cars react diff. but i was hoping it would be ok... it looks like the 60# will have to be ordered now....

06black,
what about the plugs?
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