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Thread: 95 454 injector upgrade

  1. #1
    Fuel Injected! TheApocalyptican's Avatar
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    95 454 injector upgrade

    I have a new to me 95 k2500 Suburban with a 454 Tbi. I am rebuilding it to right around 400HP. I've checked tube injector spreadsheet and seems I will need to upgrade to earlier 454 injectors. With my current 32psi fuel pump, I will be 10psi over the recommend psi. Can I tune this out by lowering my tables, or will 10psi be too much and an adjustable regulator or different spring be needed?
    Regarding a spring, isn't the spring used dependent on the incoming pressure, not one spring always equals the same pressure? How would I figure out which spring to even use in my situation? Been a long time since I was involved with the whole tbi spring thing with my 90 suburban.
    '90 Suburban w/ pretty much stock 350 TBI, 7427 ECM Conversion, sadly sold several years ago
    '95 K2500 Suburban w/ soon to be 400HP 454

  2. #2
    Fuel Injected! PlayingWithTBI's Avatar
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    Your 95 should be running at ~28PSI with those smaller (94-95) injectors. You can get this AFPR from RV Morse Machine.

    http://www.rvmorsemachine.com/product.htm

    Here's a picture of my 5.7L with 61LB/Hr injectors running the 28LB spring from a 94 7.4L
    AFPR.jpg

    Here's what it looks like underneath, I had to bend the MAP sensor vacuum tube a little to fit the thumb wheel...
    IMG_0833.jpg
    Last edited by PlayingWithTBI; 2 Weeks Ago at 06:03 AM.

  3. #3
    Fuel Injected!
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    Quote Originally Posted by TheApocalyptican View Post
    I have a new to me 95 k2500 Suburban with a 454 Tbi. I am rebuilding it to right around 400HP. I've checked tube injector spreadsheet and seems I will need to upgrade to earlier 454 injectors. With my current 32psi fuel pump, I will be 10psi over the recommend psi. Can I tune this out by lowering my tables, or will 10psi be too much and an adjustable regulator or different spring be needed?
    Regarding a spring, isn't the spring used dependent on the incoming pressure, not one spring always equals the same pressure? How would I figure out which spring to even use in my situation? Been a long time since I was involved with the whole tbi spring thing with my 90 suburban.
    Mercruiser had a 400+ HP TBI 502 running the 2" bore TBI with high pressure 61# injectors at 30 psi. I listed the part number in the injector size thread.

  4. #4
    Fuel Injected! TheApocalyptican's Avatar
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    Quote Originally Posted by Fast355 View Post
    Mercruiser had a 400+ HP TBI 502 running the 2" bore TBI with high pressure 61# injectors at 30 psi. I listed the part number in the injector size thread.
    So would you say then that the spreadsheet calculator from here is just off by a little bit? The sheet says the 65# injectors would need 34psi and the 61# would need 39psi for 400HP and 85%dc. Or is it acceptable to be over 85 since that would only be needed at full throttle and high fueling which wouldn't be all the time?
    '90 Suburban w/ pretty much stock 350 TBI, 7427 ECM Conversion, sadly sold several years ago
    '95 K2500 Suburban w/ soon to be 400HP 454

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