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17% Overdrive dampener

2K views 11 replies 4 participants last post by  Swaie 
#1 ·
I have a P1SC on my Jeep. I'm maki g about 5psi with a 3.4 pulley. How much boost will I make with the overdrive pulley and the 3.5 pulley ?any ideas?
 
#4 ·
So from what I have seen with it installed is I used to idle at -21 and now I idle at -18. Not an exact science but that is the difference so far as well as getting into boost a hell of a lot quicker.


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#5 ·
I definitely agree with the boost building faster. In some cases explosively quicker. Ask me how I know... ;)

Not sure much can be gleaned from vacuum, which can vary from other factors. Looking at boost makes more sense to me. I just don't think you can say a 17% OD will give you that much increase across the board. Each head is going to have it's own unique compressor map. Some build linearly with RPM, others are more like a J on a graph. The specific build could affect things as well, cam, CR, etc.. Then there's the weather. I've seen over 17% variance in a single month. The only things that changed were the date and Ma Nature. I'm also not sure PSI is the end of the story. My quickest pass was at 11.91 PSI. I've made way more boost than that and ran much slower. Just too many variables... I'm not saying you won't gain 17%, just you might make more, and you might make less. But definitely go for it! One of the best mods I did. Unfortunately we did a bunch of other stuff when my OD went on, little things like a built engine, headers, and whatnot, so I can't say what I got just from the pulley, except you better have a firm grip on the wheel when you launch. ;)

One thing I'd suggest is logs before and after. Then calc your actual boost from the BARO and MAP. Much more accurate than looking at a gauge. Still gonna vary, but hey, that's part of the game...

wink
 
#8 ·
True Wink, I did header with the OD pulley. So not an exact science, like I said it is the only thing I saw different. And yes it can come on out of no where.


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#9 ·
not an exact science
That's it in a nutshell. I was watching the nationals yesterday and each team was trying whatever they could to improve times as the track got hotter. And they have reams and reams of data and veteran tuners and crew chiefs to consult. It was still hit or miss for most. The closest thing I've got is my PassViewer app. But it's only using the numbers the Trinity captures...

wink

 
#12 ·
Thanks for the input y'all. I've searched multiple threads and have only found d1 builds, not many P1SCs out there. But I have the ATI 17% ready to go on and I will also be deleting the proflow bypass valve and installing a Tial Alpha Q bov. Hope it picks it up quite a bit!
 
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