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Thread: understanding and using ford speed density calculator in editor

  1. #1
    Potential Tuner
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    understanding and using ford speed density calculator in editor

    I'm having trouble understanding the speed density calculations and having trouble understanding how to use the speed density calculator in VCM editor.
    I've read the write up of speed density calculator by Steven of hptuners several times. I've saved and read many of the post you guys have written on calculating for speed density. I think the biggest issue when doing the math, On an ecoboost application. At what point do you use the fuel trims in the equation to make changes to quad, offset, slope? Thanks for any help.

  2. #2
    Tuner in Training
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    From my experience, the speed density are not required to be change.
    Unless u had make a big changes to the engine. Such as turbo changed to NA or changed super hot camshaft.

  3. #3
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    your correct. I have a friend that is running a 2015 f150 engine/pcm in his 2004 mach 1. right now its stock. he has a blower he's getting ready to put on it. I believe ive got the air charge math correct. having trouble understanding the math in fords patent. also having trouble understanding Hp tuners calculator

  4. #4
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    From my easy understanding, the speed density calculator is used to calculate the VE of the engine in order to form the quad, offset, slope tables.
    For the starting point will be adjust the correct VCT, spark and load then using the SD calculator to edit your TIP vs load to form all the final SD tables.

    What types of blower?
    FYI, if you are using a 2015 coyote there will be a IMRC required to disable in order to remove intake manifold for the blower and requires proper tuning to the VCT and spark too.

  5. #5
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    Sorry took so long to respond. I understand ill need to command a specific mapped point.
    The VE editor is Map vs RPM. what is the data in the graph? I'm guessing air flow? pounds of air? CFM?
    the histogram does not match quadratic, slop, offset or blow through tables. maybe the answer is right in front of me. But I'm not seeing it.

    He's putting a whipple on it. with ID 1050X injectors. he has an oval whipple throttle body for it also. I know ill need to get throttle body data. I found injector data on injector dynamics site and adjusted tables to fuel pressure for return fuel system. I plan on taking quite a bit of spark out to start with. From what I understand, figuring out the math for speed density or the speed density editor will help me tune VCT correctly for removing IMRC and adding the super charger.

  6. #6
    I found a whipple read for a 15+ f150 that has the speed density calibrated for that. If you?re going to run a blower on one that?s what I?d start with. I?m going to do something like that when I finally throw a blower on my truck next year. Then adjust it from there.

    Na I plotted fuel trim % on a map vs rpm table and used the % change in the speed density calculator for my cobrajet manifold and it worked. I don?t know if it?s totally the right way to do it, but it worked for me. I only did it because 1, up top it was trimming in 5% or greater and 2, I put in an eco boosts sensor which changed the speed density anyhow (messed with it to see if I could get the pcm to read the sensor before I even attempted boost).

    That?s over simplified but it worked for me.

  7. #7
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    https://cobbtuning.atlassian.net/wik...+Density+Guide

    I found this info. its good. it has some of the formulas that ive been trying to figure out with examples. but then it uses terms that I can not find out how the numbers are figured.

    SARCHG = 0.001526150 (Standardized Air Charge default for a 2.3L application)

    COMPS = All applicable speed density compensations (Base, Barometric Pressor, MCT Pivot, VCT).

    how are these figured mathematically? I don't like to change numbers and hope for the best. if the math can be done to find the answer. why waste the time guessing.

  8. #8
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    SARCHG = 0.001526150 (Standardized Air Charge default for a 2.3L application) Is the mass of air in lbs to fill all 4 cylinders at STP. Essentially it's the engine displacement in air mass, you should only need to change that number if you change the displacement of the engine.