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Thread: Injectors Auto-Phasing

  1. #1

    Default Injectors Auto-Phasing

    Hello. I'm hoping someone can enlighten me on this. I want to take advantage on auto-phasing my injectors. I have my camshaft profile, however, I have a problem with Injector Placement. I'm running a 358 small block Chevy with a BDS 871 blower with two 1200 CFM throttle bodies. 8 injectors rest inside fuel rail under the throttle bodies, which sits on top of blower. My question is how to calculate or figure out the distance for Injector Placement? Thank you.

  2. #2
    Join Date
    Dec 2009
    Location
    Connecticut
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    13,946

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    "Injector Placement - Straight-line, linear distance of the fuel injector from the intake valve, as measured or approximated from the injector outlet tip to the valve seat opening, in inches."
    For more Injector End Angle information: Open the Holley EFI software & "Help" Contents (top Toolbar), and read the "Injector Phasing Instructions".
    https://forums.holley.com/showthread...-Phasing-Table (Injector End Angle Tuning Information)
    May God's grace bless you in the Lord Jesus Christ.

    '78 BRONCO: 508" stroker, TFS heads, 11:1 comp ratio, Dominator MPFI & DIS, cold air induction, dual 12" Spal fans/aluminum radiator, dual 3" exhaust/Magnaflow mufflers, Moroso vacuum pump, Accusump, engine oil & trans fluid coolers, 100HP progressive dry direct-port NOS, A/C, Lentech Strip Terminator wide-ratio AOD/2500 RPM converter, 3:1 Atlas II, modified Dana 44/60-lockers-4.10s, hydroboost/4-disc brakes, ram-assist/heim joint steering, Cage long radius arms, traction bars, 4" Skyjacker lift, 35" mud tires

  3. #3

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    Thank you Danny. I'll go to that section and will let you know the outcome.

  4. #4
    Join Date
    Nov 2013
    Location
    Chicago IL
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    1,835

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    -Scott
    Check out my race car on Facebook
    Low 8 Second 1/4 Mile Street Car.
    Soon to go 7s on a little more boost.

  5. #5

    Default

    Scott, I've used your method to get the injector phase angle on a couple different engines. One had huge 850 lb/hr injectors and the other had 160 lb/hr injectors. I noticed that the values I was getting after adjusting the offset like you said went from 0 on the left column to -11.4 on the far right column on the large injector engine, and from 0 to -64 on the 160 lb/hr injector engine. Just for fun, I put 36 lb/hr injectors in the same tune. That gave me 0 to -149. Changing the distance the injector is from the valve make a large difference as well, and I understand why that is. What I don't understand is what effect the size of the injector would have in determining the end of injection angle. The fuel table is all zeros, so why would injector size matter in this equation? Both engines were 8500 RPM engines, so that wouldn't effect it. Thanks, Stan

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