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Detroit Diesel Injectors

Discussion in 'Engines' started by CaptOz, Jun 5, 2015.

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  1. CaptOz, Jun 5, 2015
    #1
    CaptOz

    CaptOz Member

    Joined:
    Apr 13, 2009
    Messages:
    100
    Location:
    Miami, Fl
    Hi Everyone,

    I have started to rebuild my mains and I am trying to find out what my original injectors where on my engines.

    I have a pair of 930HP Detroit Diesel 12v71 TI's marinized by BK Power in Miami, Fl back in 1986.

    Engine Model Number: 7122-7302
    Engine Serial Number: 12VA80293

    According to Detroit, the stock injectors are:
    Part Number: 5229715
    Type: 9215

    The Actual Injectors that are in there now are:
    Part Number: 5226575
    Description: JF60
    Type: 9A31

    I called an injector place and they said these are military injector for high fuel flow and that they replace the original 9215's.

    When I purchased the boat I remember the broker telling me that the engines had been detuned with smaller injectors. Probably 800-850hp ones.

    So I am trying to figure out what were the Injector BK power used to get 930Hp and I would also like to know how much horse power the current injectors are producing.

    I will start another thread showing the entire rebuild process with pictures, etc.

    I hope some one on hear knows some one that knows some one that can tell me.

    Thanks in Advance!
    CaptOz
  2. CaptOz, Jun 5, 2015
    #2
    CaptOz

    CaptOz Member

    Joined:
    Apr 13, 2009
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    100
    Location:
    Miami, Fl
    IMG_2170_small.jpg
  3. Capt Ralph, Jun 5, 2015
    #3
    Capt Ralph

    Capt Ralph Senior Member

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    Sep 8, 2004
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    13,427
    Location:
    Satsuma, FL
    Don't just buy any injector off the shelf and slam in it. Ensure they are all popped by a good local rep and all are close in spec with each other.
    Were in More Haven FL. Just crossed Lake Okeechobee (Never again). Away from my notes.
    I do remember something about 71xx injectors were better than 70xx (that may be 92s issue).

    SS may have some ideas.
  4. P46-Curaçao, Jun 5, 2015
    #4
    P46-Curaçao

    P46-Curaçao Senior Member

    Joined:
    Mar 8, 2013
    Messages:
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    Location:
    Curaçao (CW), Hollywood (FL) and Amsterdam (NL)
    Visit or give them a call:

    Mr. Todd Barnes
    Fuel Injection & Turbocharger Shop Manager

    RPM Diesel Engine Co
    2555 State Road 84
    Fort Lauderdale, FL 33312
    (Google for phone number)
  5. CaptOz, Jun 8, 2015
    #5
    CaptOz

    CaptOz Member

    Joined:
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    Location:
    Miami, Fl
    Todd was not there today but Spoke to Jose.

    He said that the 9215's is a smaller injector than the 9A31s.

    9215 Spray: 1.09 - 1.17
    9A31 Spray: 1.27 - 1.35

    He said the 9A31's are used on 12v92.

    I just am trying to find out which Injectors BK power used.
  6. Capt J, Jun 9, 2015
    #6
    Capt J

    Capt J Senior Member

    Joined:
    Jul 11, 2005
    Messages:
    14,524
    Location:
    Fort Lauderdale
    What rpm's did the engines turn WOT with the smaller injectors? 9215's are 110 liters per hour of fuel. 9A31's are 130 liters per hour of fuel....130 LPH is what the 92's came with and have even seen 140-160 LPH's in them depending on who marinized them.....110 LPH is standard for 12v71's TI......930HP is a heck of a lot out of a 12v71TI, but how many hours did you get out of them? 110 LPH's will get you somewhere in the neighborhood of 850-875HP.......How is the boat mostly run? Does it matter what BK power origionally put in them?
  7. CaptOz, Jun 10, 2015
    #7
    CaptOz

    CaptOz Member

    Joined:
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    Location:
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    Capt J,

    Thanks for the info! I guess the 9A31's is what gives 930hp to the BK Power marinezed engines.

    When I bought the boat the port had 2100 hrs and the Starboard had 1000. I put 1300 hours on them. Port engine is done. Probably need overhaul at 2500 hrs. I dont know how they were treated before me but I have always run them at 1850 or less.

    Im not looking to get 5000 hrs either, another 3000 is fine.

    I am concerned that maybe the 9a31's pump too much fuel for my engine and I will always see grey smoke in the trail. Do you think that might be true? (Dont understand why BK power would use them though)
  8. Capt J, Jun 10, 2015
    #8
    Capt J

    Capt J Senior Member

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    What top RPM are you getting at WOT? If you're getting 2300rpm's and over, then you're not overpropped. If you are overpropped you will be putting more load on them and usually see some smoke and I would tackle that as well. Grey could be unburned fuel and might be why you see the smoke or the engines are worn. If you go with smaller injectors than what you currently have then you will have to take some pitch out of the props. How does the boat run and how do the engines sound at 1950 rpms and what are your speed differences? If the engines sound like they're laboring less at 1950 rpms, then that is where I'd run them versus 1850rpms. Usually they burn cleaner as the injectors do a better job at metering the fuel and the combustion chamber heat does a better job at burning it off.

    Back in the day rebuilds were cheap (relatively speaking) and most owners didn't put a lot of hours on their boats, so most were concerned with as much HP as they could get out of a block. So most marinizers hot rodded the engines like Johnson Towers to get as much power out of them as possible, obviously shortening the lifespan. I would also check your turbo's against what is factory as it was common to run a larger turbo AND the larger injectors. Does your boat have DDEC computers?
  9. CaptOz, Jun 10, 2015
    #9
    CaptOz

    CaptOz Member

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    Location:
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    Just Spoke with Todd and he confirmed 9a31's is what BK Power used. Engine prop shaft power are 900bhp.

    9215 produce 850bhp prop shaft power