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Building a better db2

Discussion in '6.9L IH & 7.3L IDI Diesels' started by Thewespaul, Apr 25, 2019.

  1. Thewespaul

    Thewespaul Supporting Vendor Supporting Member

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    Today I am spending the day on the stand testing some db2 ideas I’ve had, and wanted to share what I have going on. Today’s pump is a late model db2 case with a torque screw, no leaf spring, locked advance set at 6*, no transfer pump blades or regulator, and a 4500 governor spring.
    C1DCB44B-1408-432A-BF9C-9ECA6467F096.jpeg

    I am experimenting with running no transfer pump so that I can externally control the transfer pressure to be able to dial fuel back without adjusting the ip itself, and to build a stronger pump that can handle more ccs and rpm. Once we start pushing these db2s to their limit we run the risk of transfer pressure spikes with the internal pump and regulator, which is what will seize a head and rotor in the case and grenade a pump. By externally supplying the transfer pressure we can more steadily control the transfer pressure to alleviate the spiking issue. I will update as we play with this pump more throughout the day, and possibly start another thread dedicated to the db4 we are running next, assuming all goes well with this pump.

    First run we were just feeling things out, found that 65 psi inlet pressure produces the most fuel for 1500 rpms, with 110ccs there and over 20 psi housing pressure. We found the higher housing pressure to be limiting our fuel up top as the housing pressure pushes against the plungers not allowing them to travel out fully. We gutted the return and are gonna run it again, more to come.
     
  2. Goose_ss4

    Goose_ss4 Full Access Member

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    Yes finally. Cant wait!
     
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  3. The_Josh_Bear

    The_Josh_Bear Full Access Member

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    :popcorn:popcorn:popcorn
     
  4. Thewespaul

    Thewespaul Supporting Vendor Supporting Member

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    Were back to the drawing board on the locked advance, but just broke through 150cc which was the goal for the day.
     
  5. Ironman03R

    Ironman03R Full Access Member

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    Eliminating the transfer pump is the old school method of making a rotory pump produce big numbers. I was looking I to it but all the info I could get led me to believe that there wasn't a balance between all out power and driveability.
     
  6. Goose_ss4

    Goose_ss4 Full Access Member

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    Where is this drawing board? ???
     
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  7. Thewespaul

    Thewespaul Supporting Vendor Supporting Member

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    What pump was that? I don’t believe anyone has built a ford db2 without the transfer pump and reg assembly
     
  8. Thewespaul

    Thewespaul Supporting Vendor Supporting Member

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    Cobwebs of my imagination haha
     
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  9. Thewespaul

    Thewespaul Supporting Vendor Supporting Member

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    So we ran this pump and maxed out our fuel supply on the bench, about 80psi of inlet pressure is all this Bacharach will make. The internal transfer pump will do much more than that if you crank down on the regulator spring, but the limit to these housings is about 140 psi from experience. The pump made good fuel with no tp, but getting the idle fuel correct would require tp, and more fuel could be had with more inlet pressure, so we installed a new liner and blades and setup the internal regulator. That’s where we picked up from 130cc to just over 150ccs. Checked idle spec and the transfer pressure was still on the low side, did some thinking and remembered there is a tiny oiling port for the advance piston where we now have nothing. We disassembled our setup for locking the timing and replaced it with the factory setup and now our tp is back up. That brought our idle fuel in spec, checked hot cranking and got 130-140 ccs depending on temp. Minimum spec is 12 ccs there, so we won’t be having any hot starting issues. Going to run this pump for the time being without locked timing while I figure something out for the oiling port, we may install a advance piston backwards and then use a second plug on the driver side, but that would really limit how much advance we could get.

    Afterwards it seemed like we hit a wall past 150, tried cutting down the guide stud but more, cutting down delivery valve spring, and gutting the return, all things that we know add up to small gains in fuel on most pumps, but got no gains here.

    I think 150 is about the limit to what this head and rotor can do in its current shape, a new head and rotor would likely make more fuel, but at the tune of an additional $1200. We do have some nos 6.2 head and rotors with 29 valves that we may try, but the smaller valves is going to be a big limitor I think.
     
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  10. IDIBRONCO

    IDIBRONCO IDIBRONCO

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    So who is this "we" that you keep mentioning? Is someone working for you now?
     
  11. Thewespaul

    Thewespaul Supporting Vendor Supporting Member

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    “We” would be my fuel guy and myself. He’s not an employee, but with his 40+ years running his own fuel shop and knowledge from engineering for caterpillar, he’s an invaluable friend to have.
    I just don’t have a clean enough space to keep and operate my stand in my own shop, so we use his facilities for these shenanigans, and for all my customer pumps which he builds and tests there.
     
  12. Goose_ss4

    Goose_ss4 Full Access Member

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    What kind of torture test are planning for high cc pumps? With the modifications I have seen and done to other pumps I saw issues after running the pumps for a extended period of time shut it off and then try to crank it with zero fuel delivery. Happened on my dad's Cummins ve pump build . Ended up being the head swelled in the housing after about 30 min of driving and could not get it to fire again until it cooled down
     
  13. Thewespaul

    Thewespaul Supporting Vendor Supporting Member

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    This pump is going on project Jerry, it was going to go on the shop truck but it’s down a hole at the moment
     
  14. Ironman03R

    Ironman03R Full Access Member

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    Your not gonna find much info about it on the internet, it's the way pumps were built for tractor pulling before the inline pumps came to be. Even though it was 20+ yrs ago the pump builders still seem to be tight lipped about it. My research came up with a bunch of dead ends.
     
  15. IDIBRONCO

    IDIBRONCO IDIBRONCO

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    Awesome! I just wasn't clear on the word.
     
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