Results 1 to 3 of 3

Thread: etc area scalar

  1. #1
    Potential Tuner
    Join Date
    Jun 2014
    Posts
    9

    etc area scalar

    2006 silverado going from a 78mm tb to a gto 90mm tb I know I have to adjust the etc area scalar. I have downloaded the xls file, it has two tabs, a tb change size area ratio and a effective area per 1%. Im grasping im going from a certain area to a larger on. what is the formula i need to use to put into the etc scalar the correct number? and how do i use the spreadsheet? im assuming theyre all pretty much the same...

  2. #2
    Quote Originally Posted by ehrke18 View Post
    2006 silverado going from a 78mm tb to a gto 90mm tb I know I have to adjust the etc area scalar. I have downloaded the xls file, it has two tabs, a tb change size area ratio and a effective area per 1%. Im grasping im going from a certain area to a larger on. what is the formula i need to use to put into the etc scalar the correct number? and how do i use the spreadsheet? im assuming theyre all pretty much the same...
    I just dropped in the gto value in for etc area scalar. Never had a issue. I don't understand why you'd need excel to tell you that
    06 Grand Prix GXP, LS4-full bolt ons, Tuned by me

  3. #3
    Senior Tuner edcmat-l1's Avatar
    Join Date
    Aug 2006
    Location
    5BA8
    Posts
    3,051
    There are at least 2 different ETC scalars used for 90mm throttle bodies. 4725, and 5636. You can try using either, and work from there.

    I do not, and have never used a spread sheet for figuring ETC scalar. My method, and what I recommend to people who ask, is dial in the tune/idle with the original throttle body, and then swap for the larger, and tweak the scalar until the idle behavior and idle airflow numbers are close to that of the stock throttle body. In theory, you should be able to swap throttle bodies, adjust the scalar, and have everything else be the same. Doesn't work exactly that way in the real world, but it's closer than setting it to a random scalar number and adjusting idle airflow to make that particular scalar number work.

    EFI specialist
    Advanced diagnostics, tuning, emissions
    HPtuners dealer and tech support
    email=[email protected]