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Detroit 8v 53N

Discussion in 'Engines' started by Marishka, Oct 30, 2015.

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  1. Marishka

    Marishka New Member

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    I just bought a 1970 Commander powered by two Detroit 8v 53Ns model 5082 5000. The specifications show a horsepower rating of 283 hp. The injectors are Type 74.

    I have not been able to find any information on these type 74 injectors on the internet and make the assumption that they were original equipment in 1970. Consequently, it appears that it would be prudent to update the injectors to the N series that is all over the internet.

    My questions.

    Other than increased fuel consumption what will change will be experienced with N type injectors such as N75s, N80s or N90s? Since they are not turbocharged, will there be a horsepower increase and, if so, how much?

    What is involved in turbocharging these engines and, if done, what is the change in life, fuel consumption and horsepower?
  2. Capt Ralph

    Capt Ralph Senior Member

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    Your original injector set should have been the 5A50 or N45s.
    Unless you have a problem, stay with what you have now.

    Those big N series injectors will do nothing but smoke. If it starts at all. The largest N (& C) injector was a 50, the norms were 40 to 45. No HP increase without more air.

    Diesel engines are not like the old Chevy engines. Bigger carb, blower, big loud pipes..
    It will be very hard for anybody to soop up anything on these ole work horses.


    To hang a turbo on a diesel, you need to change pistons and liners (different compression ratios),
    Change out most of your exhaust system past the manifolds,
    Probably change the cam timing.
    Increase the heat exchanger capacity (more power - more heat).
    Increase the raw water pump size.
    Ad inter-coolers, to cool that hot tube air down before the blower.
    Ah, the big one; New 4 valve heads. What you pour in, must get blown out faster.
    Many, many, many mounting and hanging brackets.

    And you just removed any life left in the engine, Without warning a grenade will go off.

    It could be cheaper and (almost) as much fun to re-power.
    Save the old 53s for e-bay or a DDC machine shop.
  3. Marishka

    Marishka New Member

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    Thank you. Ok, I don't want smoke and agree. But, can you tell me about the Type 74 injectors and whether or not my engines, with them, are producing more than the 283 bhp?
  4. Capt Ralph

    Capt Ralph Senior Member

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    Now, If running well, go thru the water easy so to not spill any of that champagne you have on board.
    They money your saving will more than take care of the coolers & chillers & inventory & lots of fuel for a very long range. Caviar & cakes ready next round.
  5. Capt Ralph

    Capt Ralph Senior Member

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    Hang on,
    Found a couple of 8v53n leads on your model number. reading up now.
  6. Capt Ralph

    Capt Ralph Senior Member

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    List of factory injectors below.

    ddc inj 53.jpg
  7. Capt Ralph

    Capt Ralph Senior Member

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    I found the 270 hp model.
    It did have the 4 valve heads.

    No data on a 283 hp. Could be an after factory shop boosted it up a bit.
    yours is probably maxed out in hp now.

    Still can not find anything on 74 injectors in a 53. That must be the boost magic.

    I know Chris did strange (some good) things to their gas engines.

    Time to go to work. Do you have an OLD injector shop around?
    Injectors have different spray patterns, delivery rate, delivery amount and more.
    These differences are measured in micro amounts. Sometimes just enough of a micro of this, less a micro of that can give (give up) a few ponies. Maybe an old timer can help with better specs from his own injector cook book.

    Don't ever exchange those injectors. If there really 74s.
    If you ever get the a valve cover off, the injector number is on a round tag on the injector body.
    I would guess after 45 years, somebody has already played mechanic a few times, installed and timed up a set of N50s.
  8. Marishka

    Marishka New Member

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    The 5082-5000, the operator's manual gives a bhp hp rating of 283. Max rpm on the plate from the engines is 2950, And, also on the engine plate, in the column labeled "Type Equipment", the injector is identified as just 74. So, I have been at a loss to find what it is and need to know for if I ever have to replace any of them, I need to know what they are and whether they can be replaced if I ever have a problem with them.

    On horsepower rating, I do not have a clue. But, when surveyed the engines ran extremely well and had no smoke.

    One of the reasons for my questions is because I cannot find anything on a type 74 injector and am aware of the standard injectors being, I believe, N45s. I saw that Detroit Diesel was sold to Daimler Chrysler in 2000. So, calling General Motors was out. Anyway, I called Detroit Diesel in Lodi, New Jersey a few minutes ago and spoke with Andy. He had no answer for me and advised that he had to research using the engine serial numbers. I gave him the serial numbers and will wait until he gets back to me. I will post whatever I learn.
  9. Marishka

    Marishka New Member

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    Ok, I just received a call from Andy at Detroit Diesel who was able to identify what the Type 74 injector is. The Type 74 injector is an N50.

    So, I understand that that N80 0r N90 and perhaps the N70 injectors would make these naturally aspirated engines run rich resulting in unburned fuel and smoke. But, would the N70s really do that and what about N60 or N65 injectors? If known, I would like to know ho big I could go before the engines would be running rich and smoky. If they can still burn efficiently with N65s or N70s either of those should give me a conservative horsepower boost.

    I understand that turbocharging would be a major operation especially since I see the compression ratio in the specs. So, that would have to be reduced which would require all of the modifications that you speak of. So, yes, now that my head is screwed back on I fully comprehend what would be required to turbocharge and, yes, new engines would be preferable.

    When a kid I built a lot of motors, the biggest being a 427 Ford Tunnel Port which put out gobs of power. So, removing the valve covers, pulling and then reinstalling the injectors should not be a problem. I have an operators manual which is very clear on what must be done and I also downloaded a series 50 operators guide.
  10. olderboater

    olderboater Senior Member

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    Ralph told you in post #2 that the injectors were either 45's or 50's in all likelihood and didn't recommend changing them. You contacted Detroit Diesel and were told N50's, proving Ralph knew what he was talking about. You continue to talk 60, 65 and 70 although down from 75, 80 and 90. You've got 45 year old engines. Why are you so determined to change the injectors from those it was built with and for? You're playing with fire when you start doing that. Likely no one can tell you beyond a doubt what will happen, because no one has been moved to do what you're wanting to do. They can only tell you that it runs right with 50's. It might with higher but the odds are far greater of having problems than having success. As to any horsepower boost, I seriously doubt if on that boat and those engines you'd even be aware of it.
  11. Capt Ralph

    Capt Ralph Senior Member

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    Just back in, long afternoon.
    Is that a Chris or Detroit manual?

    2950 rpm,,, gad we love those screaming Gimmes.
    I think the TAs spun faster. OUCH...
  12. Capt Ralph

    Capt Ralph Senior Member

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    Best plain advice; Enjoy that champagne, don't screw with those motors.

    The 53 idle curse may be upon you if you do (whole chapter that's not free)..
  13. Capt J

    Capt J Senior Member

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    If you want to go fast, rip those old,heavy,low HP 8v53's out and install modern 6 cylinder diesels that make almost twice the power with less weight.

    Otherwise enjoy the 40 year old antiquated engines you have until they need rebuilds and be happy, then replace. That amount of money you'd spend on bigger injectors, re-pitching the props (if you even made anymore HP with larger injectors), would be a ton of money spent on very little gain if any.
  14. Marishka

    Marishka New Member

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    Got it. Thanks. I will keep a good supply of Krug Rose on ice.
  15. K1W1

    K1W1 Senior Member

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    I am impressed that an Non Turbo 8V53 can poke that HP out.

    I have done quite a bit of work on new 8V71N's which were 290 HP out of the box, we used to strip the back end off them and advance the cam timing a couple of teeth and they would make 318 Hp. I think the Injectors were N55's.
  16. Marishka

    Marishka New Member

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    Thanks for the info K1W1, I will be discussing the options with Detroit Diesel. When I have all of the available information, like that you have just provided, I will be able to decide if I leave them as they are or make a change. But, rest assured that before I am through I will know what there is to be known about these engines. The shock is that the 8v53 is just not known. If you are looking for 71s or 92s you can find tons of information on the internet. These are 454 cu in gm blocks. Once you have certain information, they are easy.

    have a great Goblin and pumpkin day.
  17. Capt J

    Capt J Senior Member

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    The 53's were not as good of a motor and subsequently replaced with the 71 series and discontinued. They also weren't as stout. Ok, if taken care of. But they had an issue of blowing head gaskets if mildly overheated, if I remember correctly.

    go to www.4btswaps.com and it tells you tons of information on the various 53 series and updates and changes to add hp etc.

    Also if you scroll way down on that page there is a DD chart showing HP/Torque ratings for 3v53T,4v53T,and 6v53T. On a 6v53 It's showing a 5c50 injector puts out (2200/2500rpm) 210/225 bhp, 5c55 230/250 bhp, and 5c60 injector 260/280bhp torque increases are much more drastic between the different injector sizes. But it's giving you an idea how much each injector size gains, about 10% more HP.
    Last edited: Oct 31, 2015
  18. Capt Ralph

    Capt Ralph Senior Member

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    The 53s are finicky and non forgiving, The 4 valve heads cracked a lot also.

    Until you hit that wall of not enough air. Remember, their naturals. Blower ratio is already maxed out.
  19. PacBlue

    PacBlue Senior Member

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    For your information:

    8V-53N = 8 x 53 cubic inches per cylinder is 424 cubic inches.

    The 71 Series started way before and was a legend starting in WW2. The 53 series came along in 1957 in pursuit of trucking /military / industrial markets. Even today there are 6V-53's being built new for the M113 Armored Personnel Carrier, as well as 8V-71's and 8V-92's for other countries land defense programs. These are new builds to relatively old specs, exempt from emissions requirements due to their military application. Proven, cost effective power to military specifications.

    Attached is a power curve and injector list for the 8V-53N, marine engine.

    Attached Files:

  20. SeaEric

    SeaEric YF Historian

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    Thank you for posting this information. I have these same engines with N50 injectors in my old 41 Hatteras. I'll have to admit that I had to Google the terminology to fully understand the fuel curve. It pretty much confirms my experience with my own boat. I tend to cruise at around 1600 RPM's and this gives me between 8 and 9 knots. The curve says 8 GPH for 2 engines. I'm happy with that.