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3.4" Pulley?

G

GTPJIM

New member
I have an 02 GTP and am I considering going to a 3.4" pulley, presently running a ZZP MPS with a 3.6", mods are ZZP Plog and Catted 3" downpipe with Magnaflow cat back, res delete, Overkill Tune, Autolite 605, Aeroforce tells me 0* KR, do you think I will get away with a 3.4" pulley?
Advice opinions respectively received.
 




GTPJIM said:
Why are you surprised?
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With almost the same mods on two of the GTPs I have had, I was seeing 5*+ of KR still with the stock pulley.. I currently run a 3.5 pulley on my 99GTP with similar mods and see over 7* of KR. Just interesting to me that your car does that well. Sounds like you may be one of the lucky ones :)
 
I've tune mine with HPTuners, and actually have it running on the rich side anytime it's in boost to try and help with some of the KR. I run 11.0/1 AFR anything past around 50-60% throttle
 
97 AutoXvette thanks for taking the time to respond to my posts and everyone else also, 97 AutoXvette, I am most definitely not questioning your tuning ability as I am very reliant on my Aeroforce gauge at this point, before even considering going from my present 3.6" setup would you recommend I go to an Autolite 104 plug first, also any idea how I can measure AFR?
 


What timing are you seeing? Chances are your at like 12* so thats why your seeing none and if thats the case your better off getting retuned because you will see more gains than if you were to drop to a smaller pulley.
 
Ginseng said:
What timing are you seeing? Chances are your at like 12* so thats why your seeing none and if thats the case your better off getting retuned because you will see more gains than if you were to drop to a smaller pulley.
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Pretty sure Will (Overkill) knows his stuff pretty good--- he tuned mine for 18* and when I run a 3.5 on my L32/genV I'm getting 0 kr with very occasional blips. I think the 3.4 is doable if he's got a lower mileage motor, not so much if it's higher. Try it out and scan it. You should be ok with 104's, lot's of people running them on similar set ups. AFR? get a wideband.
 
Agreed, if you really are seeing 0*KR and you already are at between 16-18* of timing, then a 3.4 should be fine. I run 104's in mine and they work just fine. I think those are probably the coldest plug I would run though. I ran them in another 99 GTP I had and I ended up getting some misfires (though that could have been due to a loose wire boot). If you have that aeroforce hooked up, you have a nice advantage for changing pulley sizes. quick change to a 3.4, throw in some AL104's, and see how it does. few good half throttle pulls and check your KR. IF you see nothing, step up to some WOT pulls and do the same. If you see less than 2* of KR, I'd probably stick with the 3.4 :)

Also, this thread REALLY makes me want to check out what the Overkill tune has in it... I have uploaded countless tunes on my 99 trying to eliminate knock. That tune must have something I am missing!
 
97autoxvette, do you have a wide band O2? its possible you are leaner then you think. also i have seen lean conditions before boost and entering pe that start a condition for you to kr. if your maf tuning make sure you dont have any major spikes or dips in the data. also make sure your timing table is also smooth and not major dips or spikes.
 


Z34Phoenix said:
97autoxvette, do you have a wide band O2? its possible you are leaner then you think. also i have seen lean conditions before boost and entering pe that start a condition for you to kr. if your maf tuning make sure you dont have any major spikes or dips in the data. also make sure your timing table is also smooth and not major dips or spikes.
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Good points, I can double check some of my tables. I do have a full-time AEM wideband that I use which shows me good conservative AFRs. I have not changed the MAF at all, I only modify my PE table for AFR purposes. I will take a look at my timing table this evening and see how smooth it really is.
 
Presently at WOT with my 3.6" pulley setup I am seeing 17* of timing, will that be a safe enough indication that I can drop to a 3.4" pulley?
Thanks to all that have got involved in my initial post much appreciated, this forum is a godsend for me as being in Western Canada there are not many of these cars or enthusiasts around.
 
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