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Thread: TBI High Pressure Injectors

  1. #1
    Electronic Ignition!
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    TBI High Pressure Injectors

    I reviewed some of the factory GM injectors listed here:

    http://www.gearhead-efi.com/Fuel-Inj...d-part-numbers

    I was looking at the "17104288 - Pink / Purple - 46pph @13psi - 7.4L / 454 - 94-95 *NOTE: Came with 30 PSI regulator used @ 26-32psi for 67-72pph" injector and curious how GM used these injectors in the 7.4 road vehicles and 5.7 on marine applications? What was done differently with the injectors which allowed GM to use the same injector at the same pressure to be used on 2 different size engines?

    Steve

  2. #2
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    Quote Originally Posted by sfara002 View Post
    I reviewed some of the factory GM injectors listed here:

    http://www.gearhead-efi.com/Fuel-Inj...d-part-numbers

    I was looking at the "17104288 - Pink / Purple - 46pph @13psi - 7.4L / 454 - 94-95 *NOTE: Came with 30 PSI regulator used @ 26-32psi for 67-72pph" injector and curious how GM used these injectors in the 7.4 road vehicles and 5.7 on marine applications? What was done differently with the injectors which allowed GM to use the same injector at the same pressure to be used on 2 different size engines?

    Steve
    It is all in the tuning. Also keep in mind the Marine 350 makes more HP than the road going 454 did.

  3. #3
    Fuel Injected!
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    Quote Originally Posted by Fast355 View Post
    It is all in the tuning. Also keep in mind the Marine 350 makes more HP than the road going 454 did.
    Was that due to a much larger heat sink available (in the form of the large container of water it operated on)?
    -Phil, in Charleston, SC

    '89 S10 Blazer: SOA SAS: Dana 44s, 5.7L V8, 700R4; 35s, 4.10:1; TBI with 1227747 ECM
    '94 Grand Cherokee: 4.0, 4" lift, 31s
    '90 Jeep Cherokee: In progress: 5.7L V8,700R4,NP231C, D44s. TBI with 1227747 ECM
    '87 Fiero GT: 3.8SC (initial research stage)

  4. #4
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    I didn't know the marine engines ran such high HP numbers!

    Where these 17104288 injectors any special design from the original 13 psi injectors or were they simply regular TBI injectors with the pressure amped up to 30 PSI? Would this allow for safe operation of any GM TBI injector to be operated at these higher pressures?

    Steve
    Last edited by sfara002; 09-21-2016 at 07:43 PM.

  5. #5
    Fuel Injected!
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    Quote Originally Posted by sfara002 View Post
    I didn't the marine engines ran such high HP numbers!

    Where these 17104288 injectors any special design from the original 13 psi injectors or were they simply regular TBI injectors with the pressure amped up to 30 PSI? Would this allow for safe operation of any GM TBI injector to be operated at these higher pressures?

    Steve
    They were essentially a 4.3 injector ran at a higher pressure, if you do the math , the 45 pph 4.3 injector @ 13 psi would be around 70 pph @ 32 psi , GM's thought was it would fight vapor lock by using a higher fuel pressure , aside from designing a new injector , what they already had was used and the pressure increased to fuel a BBC . Anyone who has dabbled with a TBI BBC though finds out quick enough that the injectors at that pressure were marginal for fueling at the factory settings , one of the first things I did to the stock 454 in my '94 Dually when I bought it was to revert to the earlier injectors (5235231) and ran them around 15 psi , woke the otherwise stock engine up .

    If you are going to be raising pressures , especially on the BBC injectors , I would stay with the 5235231 platform , these are much more tolerant of higher pressures than the 17104288 injectors .

    I as well as many others have run the 5235231 injectors upwards of 70+ PSI with no adverse effects on cone shape nor spray pattern.

    TOM
    Last edited by Nasty-Z; 09-21-2016 at 05:33 AM.
    1994 3500 Dually , 502 (509) , 264HR , Edelbrock MPFI , PFI '7427
    2006 Forest river-Sierra 37' 5th wheel
    1999 Astro Van, L31 Vortec , 4x4 conversion
    1994 Pontiac Sunbird "Work ride"
    1993 K-3500 "Ex-diesel" 454/4L80E - '7427
    1992 454SS "Eh Stock" , Blower & '7427 swap .
    1992 S-10 434 SBC/Tremec - '7427
    1984 S-10 , SAS, 496/700R4/205 , D44/14BFF -'7427
    1980 Z-28 454/700R4
    1977 Olds 98 Regency 403/700R4

  6. #6
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    Awesome, thanks for the info Tom. 70+ PSI, that's so much higher than the original 13 PSI as designed. So are they just relabeled 4.3 injectors? Any changes in spray pattern between the two? I assume a 4.3 at 28-32 PSI would accomplish the exact same results?

    I was thinking of running the 17104288 injectors in my mild 350 truck. I was seeking better atomization and cleaner burn through higher pressures. I had concerns about being able to get the fuel psi with the injector set right with a pressure regulator spring for a 350; as well as, minimum pulse width optimized from a 7427 PCM for low enough for idle/fueling conditions on the 350 vs the 454. I already have a pump capable of 30 PSI and Spring on hand but I don't have the injectors yet.

  7. #7
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    Remember, when you change the injectors and/or the fuel pressure, you change the base pulse width needed and should make accommodations for it in the .bin.

    Buddrow
    If it don't fit force it, if it don't force fit f&%@ it!

  8. #8
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    Right, just to confirm for the $0D mask, the BPW function is a mater of setting the injector flow rate in lb/hr. and the cylinder volume. In the case of the 17104288 at 30 PSI, should be set to 74lb/hr. I am assuming the 7427 PCM will be able to compensate enough at idle going from 61 lb/hr from the stock set up to 74 lb/hr with the 17104288 at 30 PSI. If not I would have to reduce fuel pressure from the 30 PSI on those injectors.

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