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Thread: Max psi on injectors

  1. #1
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    Max psi on injectors

    What is the maximum PSI you can run on tbi sbc350 and bbc454 injectors? I've looked but all I can find is the factory psi ratings.

  2. #2
    Fuel Injected! brian617's Avatar
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    I'm running 22 psi on 305 injectors for 73pph

    http://www.witchhunter.com/injectorcalc1.php
    89 K1500 Scottsdale 5.7L 5spd 3:42 RamJet cam Dart iron TBI heads 427 PCM swap
    95 C2500 Cheyenne 6.5L turbo diesel 4L80e 4:10 DB2-4911 Manual pump conversion 0411 PCM trans control 2Bar COS
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    Fuel Injected! BLG355's Avatar
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    I had them at everything from stock to 30psi on 5.7 injectors. Some 7.4 injectors are intended for 30psi. I had a thread about this a little while ago and there wasn't any clear answer to what was the maximum. Some people pointed out about the more pressure, the harder it is for the injector to open. I am currently running around 22psi on 350 injectors to get around 80pph, no issues to report.

    BLG
    My Build: 95 K1500, 355ci w/ OEM roller setup - zero decked, Eagle steel crank, Scat bushed H-beam rods, Speed Pro 2V flat top pistons - Rotating assembly balanced. Dart 165cc Iron Eagle S/S heads - 72cc chambers - 1.94 / 1.50 valves. Isky roller cam - 204/209 dur @ .050 - .480/.496 lift with Comp Magnum 1.6 rockers, Edelbrock 3704 intake - Bored to 52mm - 454 throttle body, Delco EP381 fuel pump @ 18 psi running through 80# 454 injectors. Hedman Headers into 3" Dynomax exhaust.

  4. #4
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    I'm wondering cause I might need to run a pair of 454 injectors at 26-28psi for my planned application

  5. #5
    Fuel Injected! BLG355's Avatar
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    at that pressure, 80lb 7.4 injectors would be able to feed about 450-475hp. I've seen 90lb injectors come up in threads and difference places, if you can find them, you could run those at 22-23psi and support the same power. I didn't have mine at 30psi very long, but I did run them at 25 psi for several hundred miles and I had zero issues, but who's to say after a few thousand miles issues could come up.
    My Build: 95 K1500, 355ci w/ OEM roller setup - zero decked, Eagle steel crank, Scat bushed H-beam rods, Speed Pro 2V flat top pistons - Rotating assembly balanced. Dart 165cc Iron Eagle S/S heads - 72cc chambers - 1.94 / 1.50 valves. Isky roller cam - 204/209 dur @ .050 - .480/.496 lift with Comp Magnum 1.6 rockers, Edelbrock 3704 intake - Bored to 52mm - 454 throttle body, Delco EP381 fuel pump @ 18 psi running through 80# 454 injectors. Hedman Headers into 3" Dynomax exhaust.

  6. #6
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    There is no such animal as a 90PPH BBC injector , the largest BBC TBI injectors are 80PPH @ 13psi .

    Injector flow ratings ALWAYS need a measured PSI to accompany them in reference , otherwise flow ratings are a moot point.

    Also, remember the flow on an injector is inversely proportional to pressure , there is a point of no return when raising fuel pressure.

    That being said , I (and others) have run the BBC injectors at upwards of 70 PSI with no measurable side effects.

    TOM
    1994 3500 Dually , 502 (509) , 264HR , Edelbrock MPFI , PFI '7427
    1992 S-10 434 SBC/Tremec - '7427
    1986 Monte Carlo SS
    1984 S-10 , SAS, 496/700R4/205 , D44/14BFF -'7427
    1980 Z-28 496/700R4
    1979 Corvette 496/700R4
    1977 Olds 98 Regency 403/700R4

  7. #7
    Fuel Injected! BLG355's Avatar
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    70 psi, whoa! i was kind of worried about 25. I guess I have nothing to worry about!
    My Build: 95 K1500, 355ci w/ OEM roller setup - zero decked, Eagle steel crank, Scat bushed H-beam rods, Speed Pro 2V flat top pistons - Rotating assembly balanced. Dart 165cc Iron Eagle S/S heads - 72cc chambers - 1.94 / 1.50 valves. Isky roller cam - 204/209 dur @ .050 - .480/.496 lift with Comp Magnum 1.6 rockers, Edelbrock 3704 intake - Bored to 52mm - 454 throttle body, Delco EP381 fuel pump @ 18 psi running through 80# 454 injectors. Hedman Headers into 3" Dynomax exhaust.

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