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Thread: Changing Injector Size

  1. #1

    Default Changing Injector Size

    Hi. Working on a blown flat V8 with a 2bbl, Hilborn injector. Had 2 120 lb/hr injectors, running out of fuel up high. Changed to 160 lb/hr (Holley) and entered correct data into HP ECU. Is the Fuel Table automatically recalculated, or do I have to do it manually? I'm very rich now just trying to idle. I thought the software recalculated? Am I wrong? thanks.

  2. #2
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    That's the benefit of a lb/hr Base Fuel Table, is that it does not need any recalculation.

    If your engine needs 300 lb/hr, it doesn't matter if your injectors are 80s or 225s, it will still need the same 200 lb/hr.
    The bigger injector just means that it has more total fuel available.
    If you use a VE % Table, the fuel is already calculated in the equation to get it from a VE% to an injector pulsewidth, so nothing to do there either.
    -Scott
    Don't forget to check out progress on my Race Car:
    Project Blasphemy - 8.07 @ 171
    Low 8 Second Street Car

  3. #3

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    Thanks. I think something got messed up when I redid the file. I'll try this again. Thanks.

  4. #4
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    Quote Originally Posted by S2H View Post
    That's the benefit of a lb/hr Base Fuel Table, is that it does not need any recalculation.
    Yes, it's a great feature! I recently changed from 42 lb/hr to 66 lb/hr fuel injectors, and it didn't require any retuning. Maybe your 120 lb/hr injectors weren't flowing 120 lb/hrs.
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: Dominator MPFI & DIS, A/C, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/X-pipe/shorty headers, 100HP progressive dry direct-port NOS, 160A 3G alternator, Optima Red battery, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, FRPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 tires.

  5. #5
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    If you change to/from an injector that's not in the drop down menu, sometimes it requires some minor changes to the fuel tables, because the proper injector data may not have been entered exactly correct.
    -Scott
    Don't forget to check out progress on my Race Car:
    Project Blasphemy - 8.07 @ 171
    Low 8 Second Street Car

  6. #6

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    Replaced Holley 120s with Holley 160s. Cracks, backfires, runs on a couple cylinders. I think something got corrupted in the file. I put the 120s and original program back in, and it runs fine. Walked away from it yesterday. I did manage to use a Shop-Vac yesterday, without a problem. Was one of those days. Gonna get back on it Monday morning.

  7. #7
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    Quote Originally Posted by DYNOBOB View Post
    Replaced Holley 120s with Holley 160s. I think something got corrupted in the file.
    Is the Actual System Pressure parameter (in Engine Parameters) set the same with both injector sets? This parameter defaults to 43 psi when the Fuel Injector Information is changed. So if you're running a different fuel pressure, this needs to be updated as well. In fact, check all the "Fuel System/Fuel Injector Information" parameters.
    http://documents.holley.com/techlibr...owdatarev2.pdf (Holley EFI Fuel Injector Flow Data)
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: Dominator MPFI & DIS, A/C, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/X-pipe/shorty headers, 100HP progressive dry direct-port NOS, 160A 3G alternator, Optima Red battery, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, FRPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 tires.

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