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Thread: Z32 maf voltage

  1. #1
    My Vtec Gives Hugs mmmbah
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    Default Z32 maf voltage

    This is for future reference. If you have any contribution please add. Tell us how much power you put down (dyno type) and your Z32 peak maf voltage when that WHP was reached.

    On the dynojet I hit 4.52V peak and made about 361whp corrected.

    The dynomite yesterday, I had 4.77V peak and put down 379.9whp.

    Please add to this what info you can. Thanks.
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  2. #2
    TunerCode, it's OnTheChip
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    What RPM did the MAF voltage peaks occur?

  3. #3
    My Vtec Gives Hugs mmmbah
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    7200rpm.

    Peak power was at 7200rpm. Injector duty (740cc) was 83%.
    BRZ Limited Dark Gray Metalllic. Oh yea.

  4. #4
    My Vtec Gives Hugs mmmbah
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    I am pretty sure that around 4V on the maf you should be around 300whp. 4.5V should be around 350-375whp. 4.7V is around the 400whp mark?
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    Not so easy to ballpark the voltages as they are not linear.

    Someone good in math could calculate the curve of the voltages and make up a respective curve in WHPs??? (Not so easy or accurate as we would want)
    SR20VE

  6. #6
    My Vtec Gives Hugs mmmbah
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    Ya, I understand that. The maf voltage is sorta exponential. So I just want to get a sort of idea on where it would be ballpark.

    You can already see the voltage isn't linear when 360whp is 4.5V and 400 is around 4.7V.
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    TunerCode, it's OnTheChip
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    Using the values from the MAF VQ table for A Z32 MAF:
    4.00V = 31689
    4.52V = 47156
    4.77V = 56223

  8. #8
    My Vtec Gives Hugs mmmbah
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    ^^^ What is that? Please explain.
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  9. #9
    TunerCode, it's OnTheChip
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    Those are the MAF voltage to Q (mass flow rate) numbers from the VQ table used to calculate TP. You are correct that the VQ table is non-linear, and different MAF sensors output different voltages at the same mass air flow rate, so the Q numbers would be better to use for your HP prediction, rather than voltage.

    Dave

  10. #10
    My Vtec Gives Hugs mmmbah
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    So what unit are these Q numbers in? And ho can you calculate flow rate to hp? Any ideas? It would be cool if we could relate the mass flow numbers to some sort of HP prediction. Even if it had a accuracy within 15% it would still be a really cool tuning tool. Small adjustments would show up as a change in flow rate...
    BRZ Limited Dark Gray Metalllic. Oh yea.

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    TunerCode, it's OnTheChip
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    Quote Originally Posted by Coheed View Post
    So what unit are these Q numbers in? And ho can you calculate flow rate to hp? Any ideas? It would be cool if we could relate the mass flow numbers to some sort of HP prediction. Even if it had a accuracy within 15% it would still be a really cool tuning tool. Small adjustments would show up as a change in flow rate...
    Q values represent relative mass flow rate and are unit-less. Take a look at this page for HP vs mass flow rate info: Technical Database - Engine
    although I don't claim to know that it is correct.

  12. #12
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    Bringing back an bit of an old thread - was searching for something
    else, found this, decided to add a data point...

    4.05v peak MAF on DynoDynamics (with Dynojet correction factor)
    = 246whp - 50 lb MSD peak = 71.7%

    Same car, different turbo, intake, exhaust, NOT on dyno:
    4.25v peak MAF ???whp - 50lb MSD peak = 80%
    4.309v peak MAF ???whp - 50lb MSD peak = 85%
    4.49v peak MAF ???whp - 50lb MSD peak = 95%

    Interpolating the Z32 VQMAP, based on 5.12v = 500whp,
    and percentages of airflow:
    4.05v = 238.2hp *pretty close to 246whp dyno above
    4.52v = 335.6hp
    4.77v = 398.2hp



    Quote Originally Posted by dfddfd2 View Post
    Using the values from the MAF VQ table for A Z32 MAF:
    4.00V = 31689
    4.52V = 47156
    4.77V = 56223
    The table I found for the Z32 VG30DETT MAF shows:
    4.00V = 30042
    4.48V = 42772
    4.56V = 45232
    4.72V = 50466
    4.80V = 53247
    Not saying either one is right or wrong - not sure why there's a discrepancy?

  13. #13
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    Coheed, how much boost were you running at the time?
    this is good info for me since Im going to use a maf voltage activated meth injection, but since I will tune on the street using wideband I dont know the whp, but Im going to need the maf voltage vs boost so the meth will activate at certain psi vs voltage, or at least close to it...
    1990CRX SOHC Vtec, reliable DD
    1992 SE-R, blown DET

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    I get about 4.15v with 520's at 75%
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  15. #15
    [DE][DE+T]
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    Quote Originally Posted by LikeTheMovies View Post
    I get about 4.15v with 520's at 75%
    That is right in line with the data points I posted above.
    The interpolating from the spreadsheet I have says 256.9hp for 4.15v.
    Same setup as your sig - 252hp? If so, the spreadsheet is pretty close.

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    you can change value points on the maf scale. voltage to q value. can actually make the car read more air to a certain extent
    I am a Nistune Dealer

  17. #17
    The Flying Dutchman
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    Here you go guys..



    Found this loooong time ago on a forum. Dont know how accurate it is, but you got the picture.
    But remember flow doesnt have to cope with your whp output since factors as A/F, cilinderpressure, wheels, pullies etc. are all part of the game to your final whp output.

    Im running a 2871 0.86 .56 trim at 1.3 bar and get 4.53V and 71% on 740's.
    Coheed runs 83% on 740's at 380whp so that makes mine at 325whp. 4.53V reads 330ish whp, so that should be about right I reckon (this is RWD sr20 S13 that is..).
    Last edited by Daniel 100NX; 09-03-10 at 04:43 PM.
    NX2000 => 276WHP/280TQ R.I.P.
    200SX S13 => SR20DET / 740 / Z32 / Toda 264 / 2871 .86

  18. #18
    TunerCode, it's OnTheChip
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    Do you know what the numbers in each column represent?

  19. #19
    The Flying Dutchman
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    ? - Voltage - ? - Percentage of capacity - Whp output

    Obviously... but its not mine.
    NX2000 => 276WHP/280TQ R.I.P.
    200SX S13 => SR20DET / 740 / Z32 / Toda 264 / 2871 .86

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    Z32 MAF VQ TABLE


    Last edited by UNISA JECS; 09-03-10 at 06:22 PM.

  21. #21
    Endless Spinning
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    I'm not sure how accurate that table is. I was around 4.28V making about 315whp...I think whatever calculations were used should be moved up on scale to fit with what people were seeing here.

    -G
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    I think a lot of the variation has a lot to do with how the MAF sensors are installed in each individual set-up. I suspect that myN62 is over-reporting voltage... not sure if it’s a bad sensor, or if it’s the proximity and orientation of the MAF to the turbo inlet.
    -dave

  23. #23
    Endless Spinning
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    anyone have any updated numbers? I find this topic pretty cool and probably one of the best ways to estimate power increase without a dyno.
    '95 200sx SER - W10(+CP Pistons)+GT2871R+S4+TurboFX+O2Induction.exe loaded successfully! (sleeper much?)
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  24. #24
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    Correct me if I'm wrong, but since we're talking about mass of air entering the engine vs. Whp output I'd expect an unreliable variation of #'s seen with different setups. Wouldn't the whp be dependent on how efficiently the engine setup is turning the charge into mechanical power against frictional losses? For example id expect a higher whp at a lower maf voltage for a setup with methanol or e85, aftermarket pulleys, than a setup running petrol and stock pulleys. Also timing would play a big factor too. I think Unisa's table is a good example of an ideal situation.

    Again feel free to correct me if I'm wrong.
    Project Green Machine
    1/4 mi. time: maybe... HP: Neigh!! Torque: Yes please....

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    as you mentioned there is a lot of variations between setups, but in general the voltgae can be used as rough estimator. air + fuel = power so if you know how much air and fuel you are consuming (MAF and injecotr pulse width) and a/f ratio, you can make a general estimate on HP, making some assumptions on parasitic losses and such.
    -dave

  26. #26
    TunerCode, it's OnTheChip
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    MAF HP is theoretical potential HP and doesn't represent actual engine HP. It is used to scale the MAF sensor voltage to mass flow rate between different MAF sensors.

  27. #27
    9k rpm crew
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    In order to get a good idea of the hp potential of a given maf, you have to know the MAF Voltage to CFM or Pound/ Minute or Kilo Gram/ hour = Potential HP.

    The problem we have, the Nissan's VQ number does not represent air mass (lb/min or kg/hr). The whole VQ table is a percentage table. The numbers represent a percentage curve.

    Some will argue the VQ table does represent air mass. But I will say then why does all different Nissan Mafs and their VQ tables end with 65535? If the VQ #s represent airmass then that would mean all the Nissan Mafs would read the same peak air amount. Intuitively, we all know they don't.

    When it comes to understanding the MAF values, we are behind the Fords,GMs,Suburus,Audi and newer Hondas. They all go by kgr/hr or lbs/min. We can thank Nissan for that with the VQ numbers, which is only a very indirect representation of actual airflow. The VQ table is a flow curve but the numbers does not represent an actual air mass unit. Hence the reason why it’s a big headache to some when switching mafs.

    If we want to know the true hp potential of the N62 maf or any other Nissan mafs, I suggest we send in some of the most popular Nissan mafs to be flow tested by the aftermarket maf tuners. They can give us the maf transfer table in cfm which can be converted to lb/min or kilogram/hr to ultimately potential hp. No more guessing the true hp potential of the maf.

    Conversion:

    Lbs/min = CFM x .069

    Kg/hr = CFM x 2.03

    1 Horse power = 1.45 to 1.6 CFM

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    good topic ....useful info ...

 

 

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