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Thread: BPW and Injector math

  1. #61
    EFI GearHead ! EagleMark's Avatar
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    (X*4*Y)/1200

    X= BPW and Y=Engine RPM.

    TBI IDC (%) = [4 * IPW (ms) * RPM]/1200

    Wrong calculation was started here in 2007:
    http://www.fullsizechevy.com/forum/g...lse-width.html

    Comes out correct to 1project2many TBI helper and all other math...

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
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  2. #62
    Fuel Injected! gregs78cam's Avatar
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    Ok, so to simplify = X * Y / 300

    My $0E shows X*Y/600, HHMMMMMM, I might need more pressure after all.
    1978 Camaro Type LT, 383, Dual TBI, '7427, 4L80E
    1981 Camaro Z-28 Clone, T-Tops, 350/TH350
    1981 Camaro Berlinetta, V-6, 3spd
    1974 Chevy/GMC Truck, '90 TBI 350, '7427, TH350, NP203, 6" lift, 35s

  3. #63
    EFI GearHead ! EagleMark's Avatar
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    You know your better at math then me...

    But you got a lot of injectors too! They fire same as TBI right? Here's MPFI
    MPFI IDC (%) = [2 * IPW (ms) * RPM]/1200

    Try out my new spreadsheet calculator, put your math skills to good use and read this thread too, here's direct link to spreadsheet:
    http://www.gearhead-efi.com/Fuel-Inj...ll=1#post20070

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
    -= =-

  4. #64
    Fuel Injected! gregs78cam's Avatar
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    I'll take a look at it. Yes they fire just like regular TBI, just alternate opposite of each other.


    EDIT: Looks pretty good Mark, you're right that first page is a lot to take in. Only recommendation I have is to label the '7247 stuff as "$0D/$0E". Oh and yes I need more pressure.
    Last edited by gregs78cam; 03-01-2013 at 01:40 AM.
    1978 Camaro Type LT, 383, Dual TBI, '7427, 4L80E
    1981 Camaro Z-28 Clone, T-Tops, 350/TH350
    1981 Camaro Berlinetta, V-6, 3spd
    1974 Chevy/GMC Truck, '90 TBI 350, '7427, TH350, NP203, 6" lift, 35s

  5. #65
    EFI GearHead ! EagleMark's Avatar
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    I moved these fuel pressure posts here Greg...

    There's some polishing to do, thanks for the mask names on sheets. It's a lot of info, but all you have to fill in is White Boxs first set. Last st are optional calculations.

    Were you happening to run up to 49% IDC on the old one?

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
    -= =-

  6. #66
    Fuel Injected! gregs78cam's Avatar
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    I would have to fire up the laptop, and check a log, but I am pretty sure I was hitting around 38% (would really be around 80%) and IPW would not go higher than 4.2ms, which is fine at 4K rpm but not at 6K.
    1978 Camaro Type LT, 383, Dual TBI, '7427, 4L80E
    1981 Camaro Z-28 Clone, T-Tops, 350/TH350
    1981 Camaro Berlinetta, V-6, 3spd
    1974 Chevy/GMC Truck, '90 TBI 350, '7427, TH350, NP203, 6" lift, 35s

  7. #67
    Fuel Injected! JeepsAndGuns's Avatar
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    I am really super lost in this thread and its all 99% over my head. But did I read something right, saying that the injector duty cycle % display in the 0D ADX is wrong?
    79 Jeep Cherokee, AMC 401, T-18 manual trans, hydroboost, 16197427 MPFI system---the toy

    93 Jeep YJ Wrangler, 4.0L, 5 speed, 8.8 rear, homebrew hub conversion and big brakes, hydroboost, 2.5in OME lift, 31x10.50's---the daily driver

    99 Jeep WJ Grand Cherokee limited, 4.0L, auto, 2wd, leather and power everything, 99% stock---the long distance highway ride.

  8. #68
    EFI GearHead ! EagleMark's Avatar
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    So far everything I've checked is only half... try this!
    Attached Files Attached Files

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
    -= =-

  9. #69
    Fuel Injected! JeepsAndGuns's Avatar
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    Tried that ADX and if it is correct, then I am going well over 100% DC when in PE and hammering on it. I saw the DC go up to 119.02% on a recored log when I was hammering on it. TPS 73%, MAP 90, 4000 RPM, and in PE. WB AFR was still at 12.6, so it wasnt going lean, but I cant speak for weather the injectors were going static.

    Are you 100% sure it is displaying the correct DC %?

    Exact same time data sample on the normal adx was 59.51% DC
    79 Jeep Cherokee, AMC 401, T-18 manual trans, hydroboost, 16197427 MPFI system---the toy

    93 Jeep YJ Wrangler, 4.0L, 5 speed, 8.8 rear, homebrew hub conversion and big brakes, hydroboost, 2.5in OME lift, 31x10.50's---the daily driver

    99 Jeep WJ Grand Cherokee limited, 4.0L, auto, 2wd, leather and power everything, 99% stock---the long distance highway ride.

  10. #70
    EFI GearHead ! EagleMark's Avatar
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    Sorry, for got you were MPFI, change the 4 to a 2 in conversion.

    TBI IDC (%) = [4 * IPW (ms) * RPM]/1200
    MPFI IDC (%) = [2 * IPW (ms) * RPM]/1200

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
    -= =-

  11. #71
    Fuel Injected! JeepsAndGuns's Avatar
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    Quote Originally Posted by EagleMark View Post
    Sorry, for got you were MPFI, change the 4 to a 2 in conversion.

    TBI IDC (%) = [4 * IPW (ms) * RPM]/1200
    MPFI IDC (%) = [2 * IPW (ms) * RPM]/1200
    Ok, did that and it changed back to what it was before in the old ADX. Same time stamp data sample listed above, its 59.51%. So I'm guessing I'm good?
    79 Jeep Cherokee, AMC 401, T-18 manual trans, hydroboost, 16197427 MPFI system---the toy

    93 Jeep YJ Wrangler, 4.0L, 5 speed, 8.8 rear, homebrew hub conversion and big brakes, hydroboost, 2.5in OME lift, 31x10.50's---the daily driver

    99 Jeep WJ Grand Cherokee limited, 4.0L, auto, 2wd, leather and power everything, 99% stock---the long distance highway ride.

  12. #72
    EFI GearHead ! EagleMark's Avatar
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    I'd say good and remember one of your logs at 61%.

    So although different format it looks like the origanal was accurate for MPFI.

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
    -= =-

  13. #73
    Electronic Ignition!
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    http://wiki.openoffice.org/wiki/Docu...ROUND_function : It specifies number of places to ROUND, if you still care.

  14. #74
    Fuel Injected! devind's Avatar
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    I have read and reread this thread trying get a better understanding of the info needed to use the TBI calculator Mark created.
    What is bsfc? And how do I know what the value is?
    Also in the calculator it gives bpc.
    If using the calculated values to tune a $42 tune is that the same as bpw?

  15. #75
    Super Moderator Six_Shooter's Avatar
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    BSFC = Brake Specific Fuel Consumption

    For N/A engines this is generally between .45 and .50, Supercharged engines between .50 and .60 and turbocharged engines between .55 and .65.
    The man who says something is impossible, is usually interrupted by the man doing it.

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