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Thread: Will DB2831-4911 deliver too much fuel?

  1. #1
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    Default Will DB2831-4911 deliver too much fuel?

    Will the DB2831-4911 deliver too much fuel to my stock 6.2 with a GM-8 making 10psi? Should I just get a reman of the stock pump or use the 4911? I'm not sure if i can simply re-adjust my wastegate settings so the turbo doesn't get out of control if I install the bigger injection pump.

  2. #2
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    Welcome aboard!

    Given the choice, I'd use a 4911 pump. Any day. The fuel volume is adjustable (internal or external), so no biggie. I wouldn't try it without EGT and boost monitoring, though. Too much fuel is more heat, and no more (or less) power.

    The (mechanical) wastegate will do what it does, regardless of anything else. Exhaust backpressure forces it open at the adjusted force/pressure. Overfueling, if that happens, will just send the extra fuel, combusted or not, out the wastegate. Any time the wastegate is open, it's wasting efficiency. It's a balance/trade solution. There are more efficient turbos available that are more suitable to your project. A properly sized turbo will allow you to use the extra fuel and gain additional power, without sacrificing durability (within limits, of course). The GMx turbos are a balance of lower and upper response, so increasing one will, generally, take away from the other (overly simplified).
    1985 Blazer 6.2
    2001 GMC 2500HD D/A
    dmaxmaverick@thedieselpage.com

  3. #3
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    Also, upgrading the pump will require the correct fuel injector lines (pump fittings are a different angle). They are not interchangeable.

    Injector length also requires lines that fit. 6.2L injectors are long, while 6.2L van and HMMWV injectors are short, like all 6.5L injectors. All the injectors will fit all engines/heads (lines notwithstanding), except 1982 heads.

    Clear as mud, eh?
    Last edited by DmaxMaverick; 04-30-2020 at 21:13.
    1985 Blazer 6.2
    2001 GMC 2500HD D/A
    dmaxmaverick@thedieselpage.com

  4. #4
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    Quote Originally Posted by DmaxMaverick View Post
    Also, upgrading the pump will require the correct fuel injector lines (pump fittings are a different angle). They are not interchangeable.

    Injector length also requires lines that fit. 6.2L injectors are long, while 6.2L van and HMMWV injectors are short, like all 6.5L injectors. All the injectors will fit all engines/heads (lines notwithstanding), except 1982 heads.

    Clear as mud, eh?
    Thanks for the info. I was trying to find out exactly which injection lines I would need but it looks like there are a few different lengths and fittings. Would I just need to buy 6.5 injection lines? I'm not sure if those will work with my current injectors. I was able to retain the stock long injectors even with the turbo.

  5. #5
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    I don't think the 4911 pump was never used with 6.2L long injectors, so the lines probably don't exist. I've never seen/heard of them. You could use a complete 6.5L fuel system: 4911 pump, injectors and lines, and adjust fueling to keep it in the safe zone. I do not recommend tweaking lines to make them fit, which is possible.
    1985 Blazer 6.2
    2001 GMC 2500HD D/A
    dmaxmaverick@thedieselpage.com

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