Dismiss Notice

Welcome To CK5!

Registering is free and easy! Hope to see you on the forums soon.

Score a FREE t-shirt and membership sticker when you sign up for a Premium Membership and choose the recurring plan.

6.2/6.5 Injection Pump Question

Discussion in '1982-Present GM Diesel' started by BigCUCV, Nov 29, 2002.

  1. BigCUCV

    BigCUCV Registered Member

    Joined:
    Nov 29, 2002
    Posts:
    16
    Likes Received:
    0
    Location:
    Toledo/Ohio - Bavaria/Germany
    Hi there,
    I own a '85 CUCV and I have the chance to get a cheap, freshly rebuild 6.5 Injection Pump.
    Will it give me more Horses instead of the 6.2 Pump?
    Do I need to replace the 6.2 Injectors with 6.5 Injectors or are they the same?
    Are there any other modifications or adjustments to do, or can I just install the Pump and the Baby is ready to go?
    And what is the Stanadyne No. of the mechanical 6.5 Pump? (Just want to make sure that this guy sells me the right Pump)
    Any help would be appreciated!!!!!
     
  2. arveetek

    arveetek 1/2 ton status

    Joined:
    Mar 1, 2002
    Posts:
    722
    Likes Received:
    0
    Location:
    Granby, MIssouri, USA
    Every year GM diesel has two different pumps available...a light duty, and a heavy duty.

    A heavy duty 6.5L pump will give you more power than any 6.2L pump.

    The most desired pump is the DB2-4911 pump. This is the '93 (last year of mechanical injection) heavy duty pump.

    The DB2-5056 is the light duty 6.2L for 1993.

    The DB2-4949 is the heavy duty 6.2L 92-93.

    The DB2-4977 is the light duty 6.2L for 1992.

    To get the most benefit out of the 4911 pump, you'll need to replace the injectors with the 1993 heavy duty 6.5L injectors, and use 6.5L injector lines. The 6.5L injectors are slightly shorter than the 6.2L, and it's easiest to use 6.5L lines with them.

    Casey
     
  3. BigCUCV

    BigCUCV Registered Member

    Joined:
    Nov 29, 2002
    Posts:
    16
    Likes Received:
    0
    Location:
    Toledo/Ohio - Bavaria/Germany
    hey arveetek,
    thanks for the detailed Information!!!!
    the Pump that Guy wants to sell is a DB2-5079-J
    Without 6.5 Injectors (would say they are another 500Bucks, aren't they?), is the Power Improvement worth a new Pump, or should I just stay with a regular 6.2 Pump?
     
  4. KRUM

    KRUM 1/2 ton status

    Joined:
    Dec 17, 2001
    Posts:
    159
    Likes Received:
    0
    Location:
    Signal Mtn
    not to butt in gut i have been wondering about the price of a new/remanufactured pump for my 6.2 diesel and i would probably want the 93' hd 6.5 pump you listed.
    thanks,
    Jerry
     
  5. BigCUCV

    BigCUCV Registered Member

    Joined:
    Nov 29, 2002
    Posts:
    16
    Likes Received:
    0
    Location:
    Toledo/Ohio - Bavaria/Germany
    KRUM:
    for a rebuild Pump he is asking for about 300 to 350bucks with a used Pump in exchange!
    for a new pump he wants about 800bucks
    the problem is that the Pumps are in Germany!
    check here:
    web page
     
  6. BlueBlazer

    BlueBlazer 1/2 ton status

    Joined:
    Feb 15, 2001
    Posts:
    1,940
    Likes Received:
    0
    As far as I know, ALL DB2s have the same plunger diameter, so this means that the only difference between a " heavy duty " and "light duty " would be the maximum fuel setting and possibly a different governor spring setup. As far as the fuel setting goes, all you have to do is turn in the maximum fuel adjustment on any of the pumps to get the same amount of fuel. So, it wouldnt make sense to pay any extra money for a 6.5 pump if a 6.2 pump can put out the same amount of fuel. As for the injectors, they probably just have a higher pop pressure, but if the orifice size is also different then it would be worth the swap. If I were you I would find out the exact differences in the two injectors.
     
  7. arveetek

    arveetek 1/2 ton status

    Joined:
    Mar 1, 2002
    Posts:
    722
    Likes Received:
    0
    Location:
    Granby, MIssouri, USA
    I'm not familiar with the 5079 pump. GM did use several different pumps over the years.

    Casey
     
  8. arveetek

    arveetek 1/2 ton status

    Joined:
    Mar 1, 2002
    Posts:
    722
    Likes Received:
    0
    Location:
    Granby, MIssouri, USA
    Actually, I used to think the same thing, that it was all a matter of fuel delivery, which it is. However, the pumps aren't all the same. I'm burning all the fuel I can now with my light-duty pump.....I'm seeing EGT's of 1400 degrees and lots of black smoke.

    I asked about this on the Diesel Page, and this is the official answer I got:

    "I have a question regarding fuel injection pumps. I understand that the DB2-4911 pump is supposed to be the best for a 6.2L/6.5L mechanical fuel injection, high-performance engine.

    My question is, what makes this pump different than the "C" code pump that is currently residing on my 1982 6.2L? My pump was rebuilt several years ago, and then I turned up the fuel metering screw about a 1/4 turn. I can see EGT's in excess of 1400 degrees on my N/A engine if I'm not careful, and the black smoke just pours out the pipes when I lay hard on the right hand pedal.

    There must be more to the 4911 pump than just more fuel delivery...I've already got more fuel than I can burn with my stock pump. What other differences are there in these pumps?

    Thank you very much.

    Casey Flint


    * * * * * * * * * * * *

    Hi Casey,

    The major improvement of the -4911 over the earlier heavy-duty NA pumps is the rate at which the fuel is injected, much higher flow rates. I have mentioned before that the -4911 pump should be used with 6.5LTD injectors to get the full benefit. For maximum efficiency all the fuel should be injected and burned at top dead center; then it has the maximum time to expand and push on pistons and develop power. Fuel injected later does not do as much work on the pistons, and exits as HOTTER exhaust. As work is extracted, the exhaust cools down.

    Your heavy duty NA pump, turned up, is putting in more fuel, but slower so more is injected as the piston is already traveling down on the power stroke. As you know, the air can only burn so much of the fuel, and the partly-burned excess fuel ends up as black smoke in the exhaust.

    If even that partial burning had occurred earlier in the combustion process, it would have imparted more force to the pistons, and resulted in higher power.

    Cheers, Dr. Lee"



    Basically, as I understand it, the 4126 pump that I have cannot be turned up to the point to where it will compete with the 4911 pump, due to internal differences that control flow rate and delivery.

    Also, as you said, higher pop pressures also help performance.

    On a diesel, the better the fuel is atomized, and the quicker it is injected, the more effecient it becomes, and the more powerful it becomes. That's why the newer diesels, like the Duramax, run fuel pressures of about 19,000 psi. Our 6.2L's run around 1500 - 1900 psi.

    Casey
     
  9. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

    Joined:
    Jul 23, 2000
    Posts:
    36,180
    Likes Received:
    1,388
    Location:
    E-town baby!
    Damn I'm learning some cool stuff in this forum!! Great answer Casey!

    Rene
     
  10. DieselDan

    DieselDan 1/2 ton status

    Joined:
    Jan 27, 2001
    Posts:
    1,056
    Likes Received:
    0
    Location:
    Vermont
    Good info from Dr. Lee /forums/images/graemlins/laugh.gif I've noted that the list of DB2 part numbers also differs from the civilian trucks to the military CUCV and HMMWV models. Now I assume the difference between all these (-4126) pumps is fuel rate, delivery, and govenor limit. In heavy truck applications the more loaded (heavier)the vehicle,the more de-rated the engine will be. Wouldn't it stand to reason that even in our 6.2s that the HD application pumps (not including the 6.5 pumps) might not provide the greatest HP or torque figures. /forums/images/graemlins/smirk.gif Whaada think?
     
  11. BlueBlazer

    BlueBlazer 1/2 ton status

    Joined:
    Feb 15, 2001
    Posts:
    1,940
    Likes Received:
    0
    OK, what Im gathering here is that you are not running a turbo, correct? If this is so, the reason that you have black smoke and high EGTs has nothing to do with the efficiency of the pump or the "flow rate" as he calls it, but has everything to do with the timing and lack of fresh air. IF this 6.5 pump supposedly puts the fuel in quicker, this is just the same as advancing the timing, so in theory if you advance your timing with a "light duty" pump, you should get the same effect. Im guessing that the only big difference between these two pumps is the profile of the cam ring that actuates the plungers. Now, having said all this, I think that if you are keeping your engine NA, then there is no point to changing the pump out for a different one unless your getting a great deal on it. I dont think it would be worth paying any extra for it. Now if you were going turbo, it might be worth it, but I still think that a stock pump turned up with a little bit of advanced timing (not good for these motors) and a healthy amount of boost and you will do as good as you can.

    Keep in mind that this is just conversation, not meant to be argumentative.
     
  12. BlueBlazer

    BlueBlazer 1/2 ton status

    Joined:
    Feb 15, 2001
    Posts:
    1,940
    Likes Received:
    0
    </font><blockquote><font class="small">In reply to:</font><hr />
    In heavy truck applications the more loaded (heavier)the vehicle,the more de-rated the engine will be. Wouldn't it stand to reason that even in our 6.2s that the HD application pumps (not including the 6.5 pumps) might not provide the greatest HP or torque figures. Whaada think?

    [/ QUOTE ]

    I dont get the part about heavier trucks being de-rated.
     
  13. DieselDan

    DieselDan 1/2 ton status

    Joined:
    Jan 27, 2001
    Posts:
    1,056
    Likes Received:
    0
    Location:
    Vermont
    derated lowered available output than maximum possible. Look at like this: Diesels don't like being operated in an over-fueled condition. Internal temps can quickly reach critical mass. The point where a motor reaches this condition has a lot to do with the particular application. You could get away with cranking the wick quit abit in 1ton Dog Cummins (even though Dodge runs them derated to keep the drivetrain together and the warranty claims to a minimum), but the same motor would probably resemble Chenobyl if it where pulling a 2ton delivery truck up a steep grade. IMHO /forums/images/graemlins/grin.gif
     
  14. arveetek

    arveetek 1/2 ton status

    Joined:
    Mar 1, 2002
    Posts:
    722
    Likes Received:
    0
    Location:
    Granby, MIssouri, USA
    Yes, I'm currently N/A, and that is why I have such high EGT's and black smoke...not enough air to burn the available fuel. However, DR. Lee's newest engine (did you read that article?) is using the 4911 pump in an N/A application.

    Advancing the timing will inject the fuel sooner, but not quicker. Make sense? If you advance the timing, the fuel will be squirted in sooner than it was before, but still at a slow rate. A pump that is designed to squirt the fuel in at a much quicker rate will be able to produce more power at the same set timing.

    In other words, an older-designed light duty pump may be set to deliver more fuel, and the timing may be advanced to deliver that fuel sooner. However, even if you inject that fuel sooner, because it has a slower flow rate, and takes longer to inject, the fuel is still being injected after the piston is already being pushed down by the explosion taking place. The flow rate may be slow enough that fuel is still being injected after the burn has started.

    Perhaps the 4911 pump has been designed to inject the fuel quicker, so combined with advanced timing and fuel delivery, it can squirt the fuel in all at once for a complete burn before the piston has really started to travel. Getting all the fuel in and burned as quickly as possible is what we're after on any engine, gas or diesel.

    I agree.....purchasing a 4911 pump and 6.5L injectors to put on a stock N/A engine probably won't gain you much though.

    I'm not trying to be argumentative either....I just enjoy talking about my favorite subject....diesels!! /forums/images/graemlins/laugh.gif

    Casey
     
  15. arveetek

    arveetek 1/2 ton status

    Joined:
    Mar 1, 2002
    Posts:
    722
    Likes Received:
    0
    Location:
    Granby, MIssouri, USA
    I seriously doubt the heavy duty pumps were meant to be derate the engines. The J code heavy duty engines have a higher, though not by much, horse power rating than the C engines.

    Casey
     
  16. BlueBlazer

    BlueBlazer 1/2 ton status

    Joined:
    Feb 15, 2001
    Posts:
    1,940
    Likes Received:
    0
    Its kind of hard to explain what Im getting at, but Ill try and explain it to you. You have two DB2s lets say that have exactly the same fuel setting ( maximum fuel setting ). Now, this means that for each stroke of the plungers, they will inject the same amount of fuel. So lets say you have a pump with a different cam ring that has a faster rate of actuating the plungers like this HD pump you speak of. Then you have one that is LD and has a "milder" profile to the ring. Now, since they are at the same fuel setting, the way a DB2 works, they will both inject the same amount of fuel. However, they will have a different "rate shape" (Caterpillar terminology). This means that if you look at the amount of injected fuel from the beginning of injection to the end of injection on an HD pump on a graph it would increase very fast, level off, and then drop off very fast. The LD pump would gradually come up, level off for a lesser time, then decrease slower. This means that the HD pump in effect advances the timing because more of the fuel is being pumped in sooner compared to the LD pump. You are not injected any more fuel, and you are not atomizing much if any better, so this would result in more power, but not much more than if you set the base timing a little advanced on a LD pump. Now, you also state that with the LD pump, you are injecting the fuel later when the piston is on the downstroke. Keep in mind that injection of fuel is not instantaneous, it takes at least 20 or more degrees of crank angle to complete. So if you advance the timing on an LD pump, you will be about at the point of an HD pump. I guess what Im getting at here is that the only reason the HD is better is that your beginning of injection stays the same, but in effect you are advancing the rate of fuel delivery, but with an LD pump you can just advance the base timing to get the same effect. Everything I have just said will be wrong however if this HD pump, has a HUGE difference in cam ring profile compared to an LD pump, but I doubt it is that much. I also think that an HD pump will be harder on the internals of the engine due to the sharp spike in cylinder pressure when the fuel is injected faster. OK, thats enough typing for tonite. Later
     
  17. BlueBlazer

    BlueBlazer 1/2 ton status

    Joined:
    Feb 15, 2001
    Posts:
    1,940
    Likes Received:
    0
    </font><blockquote><font class="small">In reply to:</font><hr />
    Look at like this: Diesels don't like being operated in an over-fueled condition

    [/ QUOTE ]

    Sorry to be nit-picky, but diesel engines would not be able to increase in speed if they could not be over-fueled, when you put the governor out of balance (giving it more throttle) you are overfueling the engine, this change in fuel delivery is what changes engine speed.
     
  18. DieselDan

    DieselDan 1/2 ton status

    Joined:
    Jan 27, 2001
    Posts:
    1,056
    Likes Received:
    0
    Location:
    Vermont
    Well I won't go out on a limb and say the 6.2/6.5 were derated but HMMWVs are spec'd:

    6.2 150HP @3600 260 FtLbs @2000
    6.5 160HP @3400 285 FtLbs @2000

    How does the civy 6.2/6.5(NA) spec out?

    'Guess what we really need is someone who works at stanadyne and knows his stuff. /forums/images/graemlins/grin.gif

    PS. Ya Tyler, your gettin nitpicky /forums/images/graemlins/rotfl.gif When I mentioned over-fueled I was refering to an excess of fuel that accompanies a sharp rise in EGT, beyond the thermal design limits of the engine. Care to elaborate??? /forums/images/graemlins/wink.gif
     

Share This Page