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Dry shot a/f ratio

This is a discussion on Dry shot a/f ratio within the Nitrous forums, part of the LSx Technical Help Section category; Is anybody spraying a dry shot through an slp 85mm maf? If so, what is youre air fuel ratio and ...

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    slammed RAWPWR3's Avatar
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    Dry shot a/f ratio

    Is anybody spraying a dry shot through an slp 85mm maf? If so, what is youre air fuel ratio and where did you place the nozzle? Thanks

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    TunedbyFrost.com Tuner Frost's Avatar
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    It's gonna be rich with a stock tune. The 85mm MAF runs its frewuency to full scale long before the stock unit. Quite rich off the bottle, and VERY rich on it.

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    Thanks for replying. I guess that, along with my full exhaust and stock tune is why my car gets such poor gas mileage, and the fact that its an a4. But my main concern was that it would lean out when spraying. Do you think i could run it like that, or should i throw the stock maf on there to spray it? Also, i was looking through the hptuners forum, and i was reading about how they take out the resistor in the slp maf (i dont know why though), and they substitute a truck maf table when using and 85mm maf so it performs somewhat better. What are youre thoughts on this? Sorry 'bout the questionare and thanks in advance.
    Yulian

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    TunedbyFrost.com Tuner Frost's Avatar
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    There is no canned table to work with either MAF when used on an F-body. One may get it close, but you can't get around tuning if you want to keep and use an 85mm. Being too rich on the jug is dangerous too.

    Personally, unless you have a REASON to run a different MAF, I don't see why you would (no, because you or someone else thinks it "flows better" is not a reason ).

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    Thanks again, im not doubting you but could you please explain why its bad to have a fat mix while spraying, i thought thats what we wanted to help the extra o2 burn? Also, i asked a similar question over on hptuners and i got the response that the 85mm mafs lean out the mixture up top, and honestly thats what i thought they did, and thats why i asked the question here about the a/f mix, to make sure it would be okay before i sprayed. I still have the stock maf and will gladly put it on before spraying, im just trying to learn a little before doing anything, i dont just go by the general consensus that ls1's are indestructible and just go ahead and spray it and dont look back. I like to do my research and arm myself with knowledge before doing anything. Thanks again.
    Yulian

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    TunedbyFrost.com Tuner Frost's Avatar
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    Quote Originally Posted by RAWPWR3 View Post
    .... Also, i asked a similar question over on hptuners and i got the response that the 85mm mafs lean out the mixture up top, ....
    Whoever told you this:
    1. has a resistor modded MAF
    2. is referring to a different MAF
    3. is just wrong

    When a H/C car can run an 85mm MAF full scale (maxed out frequency) when making 440rwhp and the car after him makes 495rwhp (5psi, cam only, P1sc) with a STOCK MAF and still has 2 cells left frequency-wise (reporting less than the 85mm with only H/C), what does that tell you? If you are running an 85mm MAF, it is reporting a higher frequency at the same airflow than your stock MAF would report. It is easy to see how this works.

    If you think who told you that is right, ask them for screen shots of logs before and after with the MAF swap. Unlike them, I can produce such.

    It's true you want to be richer than NA on the jug, but it's not like forced induction, you don't want AFR numbers in the 10s either.

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    It makes alot more sense to me now after you explained it like that, Thanks. I dont think the person who told me that is right, im just doing research and asking around so i can reach my own conclusion. I have also recently started playing with my hptuners, which is why im over there, and i have ALOT to learn. I will be swapping in my stock maf again, but answer me this; the pcm commands the afr to be at 14.7 correct? What does it command it to be at wot? Is that safe for nitrous? The kit i bought off my buddy came with a lid that is drilled for the nozzle on the pass. side, is that a good location for a dry hit? Again, sorry about all the questions, i dont mean to be a bother, just trying to learn a thing or two. Thanks

    Oh and check this out...
    http://www.hptuners.com/forum/showthread.php?t=19662

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    TunedbyFrost.com Tuner Frost's Avatar
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    The unit that Mike was referring to had to have had the resistor on it. That is what Alvin was referring to in his post. They are both very knowledgeable tuners.

    Once you made the smallest of mods (yes, even a lid), it doesn't much matter what the PCM is commanding, it's not getting it until the car is tuned. This doesn't necessarily mean that you will end up in a bad place, it's just how it works.

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    Thanks again for all youre help man, i appreciate it. I havent installed the kit yet, i just wanted to get all this stuff straight before i did. Also, in about 6 weeks or so, ill have access to a dyno in my street tuning class at school. Hopefully ill have the kit in by then, and ill be able to spray it on there and check everything out to make sure its safe for use, and make adjustments as necessary with my hptuners with help from my instructor.
    Yulian

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