fuel pump pressure to 42lb injectors

Discussion in 'Troubleshooting & Diagnosis' started by purpleflame, Aug 8, 2008.

  1. purpleflame

    purpleflame Veteran Member

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    so i got this motor and it is a built lt1 396 stroked motor it has 42lb injectors and am wondering what pressure of pump I need Im assuming something around 250 psi not familiar with the pressures for fuel injection. the donor car ran but just has the stock pump in the tank and am thinking this motor needs more pressure. any help would be great to understand this.
     
  2. Rick WI

    Rick WI Veteran Member

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    Fuel pressure to the injectors is 42 PSIG. Should be easy to remember with your injector size.
     
  3. rscamaro73

    rscamaro73 Administrator Staff Member

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    Plus you can add pressure more more fuel (or pulse width).....or put in larger injectors (for shorter pulse width and room to 'grow').

    Plenty of LT1 tuners out there that'll have the scoop on 'stock LT1' engine hop ups :)
     
  4. TheFly

    TheFly Guest

    you can run a 250 if you got a regulator with a return line.
     
  5. GetMore

    GetMore Veteran Member Lifetime Gold Member

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    Those injectors should be fine at stock pressure. Pressures vary, based on the year and the EFI systems, etc, but usually start around 42 psi and might go as high as 65 psi.
    I'd guess the LT1 system uses 42-45 psi.
    The newer LS1 type engines run about 55 psi, and I think the pumps are rated for 65 psi.

    You can run the stock pump without problems, but if you want to upgrade and you don't need it you still won't have problems. The regulator bypasses the excess fuel to keep the pressure where it is supposed to be.
     
  6. Rick WI

    Rick WI Veteran Member

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    I really don't think a stock pump best for a 396 LT1. Pressure is one thing, volume though is the key.
     
  7. tom3

    tom3 Veteran Member

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    True that. With those large injectors the pressure would not have to be that high, a stock 350 runs on 22# injectors at about 40 psi. But volume/gph would be a consideration.
     
  8. V8TEC

    V8TEC Veteran Member Lifetime Gold Member

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    Try looking into a Walbro 307 or 340, they're worth 255 liters/hr. It will fit right in place where the original in-tank pump is. I ran a 340 on my Grand National, 45psi at idle/no boost, and 68psi when the boost peaked at 23psi. Never had a problem with it. Had an Accufab regulator to go with it (boost-referenced of course). Cotton's Performance in Agawam, MA should have them in stock.
     

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