Problems with 2.9 Pulley.
06-09-2008, 07:37 PM
#1
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Problems with 2.9 Pulley.
Well I've got stage 2 and its seems pretty obvious that a 2.9 is safe with stage 2. Has ANYONE had a problem resulting from putting a 2.9 pulley on? I'm sceptical about putting it on.
Problems anyone???
Problems anyone???
06-09-2008, 07:49 PM
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does anyone have solid information like logs from hpt that show a 2.9 is not good on stage 2? i'm tired of seeing these posts and people saying "yes" or "no" without backing it up.
06-09-2008, 07:50 PM
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06-09-2008, 08:03 PM
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depends on your elevation for the question to be answered but at sea level you are screwed
your beloved stage 2 and a 2.9" pulley 115% idc's and is that 5* of knock i see oh my.
your beloved stage 2 and a 2.9" pulley 115% idc's and is that 5* of knock i see oh my.
Last edited by lsjwannabe; 06-09-2008 at 08:03 PM. Reason: Automerged Doublepost
06-09-2008, 08:10 PM
#14
i have multiple logs from different cars that prove the 42# injectors were overworked with just the stage 2 pulley and gm tune. nothing else done except the stage 2 and i was seeing 20msec pulsewidths, 110% idc. with a 2.9" i was in the 130% range and 22msec pw. it would likely be the death of my car had i kept running it.
high altitudes and low air density places are the only times people can get away with smaller pulleys on stage 2.
high altitudes and low air density places are the only times people can get away with smaller pulleys on stage 2.
Last edited by Bika; 06-09-2008 at 10:16 PM.
06-09-2008, 09:59 PM
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well that spoils my fun.... i have my 2.9 on the way but now i'm having second thoughts... althought i'm at 800 feet above sea level that doesn't make me feel much beter
although from other posts people have said you can safely lean out the rich gm tune and you will no longer be maxing out the idc's.. i don't know how true that is.. but if it is true....
then who is flying to winnipeg to tune me?
although from other posts people have said you can safely lean out the rich gm tune and you will no longer be maxing out the idc's.. i don't know how true that is.. but if it is true....
then who is flying to winnipeg to tune me?
06-09-2008, 10:17 PM
#17
if your injectors are maxed, a smaller pulley will only work them even harder. the leaner afr resulting from smaller pulleys is a result of the injectors not being able to supply the demanded fuel. my afr was dangerously lean with the 2.9". i saw no gains in my 1/4 mile times or trap speeds.
06-09-2008, 10:24 PM
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This is good info 
What about compared to the gm stage 3 pulley sized at 76mm or 2.99? I realize it's not a big size difference from the gm stage 2 pulley but was curious since I have all three.
What about compared to the gm stage 3 pulley sized at 76mm or 2.99? I realize it's not a big size difference from the gm stage 2 pulley but was curious since I have all three.
06-09-2008, 10:42 PM
#22
yes.
06-09-2008, 11:01 PM
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the gm stage 3 pulley is basically a 3" pulley that you are paying over $100 for. .01" isnt going to do a thing.
the interceptor will not display your IDC%. an interceptor will display injector pulsewidth, which is actually a better indicator than IDC in most cases for measuring injector performance. dont concern yourself too much with the IDC%. all it does is provide a calculation based on pulsewidth, engine load, rpm, etc. HPTuners isnt the most accurate calculation of IDC. 19msec - 20msec is the pulsewidth where an injector is completely static (lost control of itself, cannot provide any more fuel, packing up its **** and going home)
yes.
the interceptor will not display your IDC%. an interceptor will display injector pulsewidth, which is actually a better indicator than IDC in most cases for measuring injector performance. dont concern yourself too much with the IDC%. all it does is provide a calculation based on pulsewidth, engine load, rpm, etc. HPTuners isnt the most accurate calculation of IDC. 19msec - 20msec is the pulsewidth where an injector is completely static (lost control of itself, cannot provide any more fuel, packing up its **** and going home)
yes.
thanks!, i appreciate your help. I've been thinking of getting an interceptor and thats one more reason in favour of it. everybodies car is different so it's probably best if i get one and see what my own pulse widths are before i put on the 2.9 i already bought lol.
06-09-2008, 11:05 PM
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Hey guys, I found this post that contains a formula for converting the injector pulsewidth into IDC. This should be useful for those with the interceptor and wanting to figure out IDC's.
https://www.cobaltss.net/forums/show...dth#post644739
Edit: even easier.. more searching revealed this website: http://www.stealth316.com/2-calc-idc.htm
just plug in the rpm and ipw in ms and it spits out your injector duty cycle %. I'm definitely going to try this out with my different sized pulleys. Thanks again for the good info!
https://www.cobaltss.net/forums/show...dth#post644739
Edit: even easier.. more searching revealed this website: http://www.stealth316.com/2-calc-idc.htm
just plug in the rpm and ipw in ms and it spits out your injector duty cycle %. I'm definitely going to try this out with my different sized pulleys. Thanks again for the good info!