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Thread: GTP Injectors into F-body IFR numbers?

  1. #1
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    GTP Injectors into F-body IFR numbers?

    I have a set of GTP injectores i just installed into my 01 camaro the camaros run 42 psi on the FPR. what numbers should I enter into the IFR table? Can I just copy the numbers used in a GTP

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    Quote Originally Posted by 01PewterDropTop View Post
    I have a set of GTP injectores i just installed into my 01 camaro the camaros run 42 psi on the FPR. what numbers should I enter into the IFR table? Can I just copy the numbers used in a GTP
    Are you sure the GTP run 42.5 PSI too ?

  3. #3
    Tuner in Training Rynoman2k3's Avatar
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    GTP's don't use 42# stock. They are like 32-33.5.
    1999 Pontiac Grand Prix GTP

    Ported SC/TB, Intense 3.4/3.25 Pulley's, SSAC Headers, AEM Uego Wideband, Devils Own Meth, ZZP 1.9 Modified Rockers, LS6 Springs, Manley Retainers, TransGo Shift Kit, Poly Dogbones, KYB GR2's, GMPP Brake and Suspension Upgrades, Springtech Springs.

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    im saying that the camaro runs 42 psi fuel pressure. the injectores are the gtps that run 33lbs should i just put 33 into my IFR table?

  5. #5
    Tuner in Training Rynoman2k3's Avatar
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    If you have the GTP injectors installed then yes you want your Injector table to reflect that.
    1999 Pontiac Grand Prix GTP

    Ported SC/TB, Intense 3.4/3.25 Pulley's, SSAC Headers, AEM Uego Wideband, Devils Own Meth, ZZP 1.9 Modified Rockers, LS6 Springs, Manley Retainers, TransGo Shift Kit, Poly Dogbones, KYB GR2's, GMPP Brake and Suspension Upgrades, Springtech Springs.

  6. #6
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    Quote Originally Posted by Rynoman2k3 View Post
    If you have the GTP injectors installed then yes you want your Injector table to reflect that.
    if the stock GTP fuel rail is 42.5 PSI too. I can't find the information on the web.
    The GTP stock injectors or the same the FAST #36 injectors (36@58PSI).
    They should be about #30@42.5 PSI.
    Last edited by Brice; 04-15-2012 at 01:22 PM.

  7. #7
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    http://shop.zzperformance.com/store/...Injectors.aspx

    12.2 Ohm, 354cc @ 3 Bar (33.71 lbs/hr @ 3 Bar)
    34.28 lbs/hr @ 45 psi
    Note a stock 1997 value uses a value of 38.26 which suggests GM calibrated that vehicle for an average effective fuel pressure of 56 PSI.

    Note GTP's fuel pressure is variable with vacuum and boost, but pressure across the injectors is always the same, thus flow is always the same granted your pressure changes properly.

  8. #8
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    dear OP i understand what you are asking I am about to put GTP injectors in my f-body and i had the same question as you so sorry i cant help any. to the rest of the posters here this thread is full of facepalm...

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    so 45 psi ? whats the answer ?

  10. #10
    Advanced Tuner passingpower's Avatar
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    Have a squint at this:
    http://www.fastfieros.com/tech/fuel_pressure_L67.htm

    That's a reprint directly from the GM service manual (Document ID# 564570)
    Note the factory spec in step 2; (48-55 psi) The mean average is 50.5 psi. or, approx. 3.5 bar. That's the factory target. Any one of us can verify this with a $20 fuel pressure guage. I did. It shouldn't be that difficult to find the same specs for your F-body.

    Remember too that the pressure regulator swings that down or up in a 1:1 relation to the manifold pressure. The most important thing to keep in mind is that pressure ACROSS the injectors is held at 50.5 psi. in a return regulated system. (unless the stock fuel delivery system can't keep up... Which it can't for L67.) Is it critical you have the exact value to three digits of accuracy? No! The goal here is to provide your PCM with a fuel model that is a close analog to the pressure that will occur in the real world. Is it possible to compensate for any errors? Absolutely!! That's exactly what everyone wastes their time doing when they use linear math to "scale the IFR" and fill in the gaps with hours of MAF tuning: "Take the ratio of the pressures and multiply the stock IFR by that." BS. Save yourself the road/dyno time by doing some research and using HPTuners calculator.

    Now you know the nominal rail to cylinder pressure, and if you bother to check, you'll know your own exact pressure for your application. Then it's time to use the HPTuners injector flow calculator. Spec sheet numbers are the "old" values and the above pressure is the "new" pressure. the resulting flow goes into the IFR table.

    To answer DropTop's question; If you're sure 42psi is your pressure, enter that for "new". The "old" numbers will come from the spec sheet for the injectors you plan to run. Do yourself a favor and Google the part numbers (GM and Bosch) and make the determination whether you have a 33 or 36 lb./hr. set. If it's the same as the number in the ZZP link, go with 33.71 lbs/hr @ 3 Bar.
    Last edited by passingpower; 05-05-2012 at 12:45 PM. Reason: formatting/spelling
    Check before you consider tuning;
    Is the MIL on? ANY leaks-vacuum, fluid or exhaust? Clogged filters? Old O2 or dirty MAF sensors? Dirty injectors, PCV or IAC passage? Correct the condition. Change the plugs & oil while you're at it. They need it anyway. Particular system giving you fits? Visually examine the related wiring first.