nitrous question
05-19-2011, 09:02 PM
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nitrous question
i just recently installed a zex kit on my 08 and am curious about a/f ratios.
at around 900-950 lbs of bottle pressure my a/f is around 10.5-11. should i swap fuel pills or nitrous pills? i could go with a little less fuel in the intake to lean it out some and maybe get around 11.5-12 or swap nitrous pills for the same effect and more power. zex recommends pulling 4* of timing on 100 shots or more though. the car runs good now with no detonation but im just curious as to what others are running.
at around 900-950 lbs of bottle pressure my a/f is around 10.5-11. should i swap fuel pills or nitrous pills? i could go with a little less fuel in the intake to lean it out some and maybe get around 11.5-12 or swap nitrous pills for the same effect and more power. zex recommends pulling 4* of timing on 100 shots or more though. the car runs good now with no detonation but im just curious as to what others are running.
05-19-2011, 10:09 PM
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For safety, I'd recommend changing your fuel pills to adjust your AFR. However, if you're spraying under 100 shot, then I guess you could try going slightly bigger on your nitrous jets. When you're fine tuning it (and not drastically changing the jet size) using the jets to achieve minor changes in the AFR, it really doesn't matter since you're only moving up or down by small increments, like using a step or two smaller fuel jet, in your example.
BTW, as a rule of thumb, you want to retard 2º of timing for every 50 shot.
BTW, as a rule of thumb, you want to retard 2º of timing for every 50 shot.
05-19-2011, 10:25 PM
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For safety, I'd recommend changing your fuel pills to adjust your AFR. However, if you're spraying under 100 shot, then I guess you could try going slightly bigger on your nitrous jets. When you're fine tuning it (and not drastically changing the jet size) using the jets to achieve minor changes in the AFR, it really doesn't matter since you're only moving up or down by small increments, like using a step or two smaller fuel jet, in your example.
BTW, as a rule of thumb, you want to retard 2º of timing for every 50 shot.
BTW, as a rule of thumb, you want to retard 2º of timing for every 50 shot.
well will i gain power by switching the fuel pills? zex (as well as what i read on forums) claim the power is gained more from fuel than nitrous. ideally i would like to have an efficient 75 shot setup and then increasing to a 150 shot after i get a dyno tune
Last edited by smaqaho; 05-19-2011 at 10:32 PM.
05-20-2011, 09:01 AM
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You gain power from fine tuning your AFR, either via fuel or the nitrous. Again, I recommend that you mess around with the fuel jets in the smallest increments possible, even though doing the same with nitrous will yield similar results.
Also, you don't need an aftermarket fuel pump for 150 shot. Many of the nitrous guys have sprayed 150 as-is + a tune.
Also, you don't need an aftermarket fuel pump for 150 shot. Many of the nitrous guys have sprayed 150 as-is + a tune.
05-20-2011, 03:03 PM
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i think thats what ill do. right now im running a .016 fuel jet (if im not mistaken) and i think i have a smaller size in the bag. that would make a nice little saturday afternoon project.
im scared of going over 75 on a stock tune. once i get a dyno tune for the nitrous i will up the shot to either a 125 or 150, whichever the HR motor can hold safely on a good tune
im scared of going over 75 on a stock tune. once i get a dyno tune for the nitrous i will up the shot to either a 125 or 150, whichever the HR motor can hold safely on a good tune
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05-21-2011, 11:53 AM
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05-21-2011, 12:26 PM
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this is the kit i have
http://www.zex.com/zx/nitrous-system...trous-kit.html
plus zex's window switch
http://www.zex.com/zx/nitrous-add-on...ml?___store=zx
07-26-2011, 03:10 PM
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to add to the already good info you got from others here, the lean spikes can happen, and usually the system will allow you to set a predetermined time limit to allow for those spikes. for example, if you set the limit to 0.5 seconds and the a/f ratio to 12:1, then once it sees an a/f ratio above 12:1 for more than half of a second, it will cut power. this is how you can allow for the lean spikes.
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