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MAN V10 - 1050hp LE403s

Discussion in 'Engines' started by SomeDevil, Nov 29, 2020.

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  1. SomeDevil

    SomeDevil New Member

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    I own a 2004 SeaRay 600SS with MAN 1050s -- looking to make the run from Milwaukee WI to Ft Lauderdale next year. Wondering if the cylinder cut-out feature will make this a rough trip on the motors during the many No Wake Zones on the ICW and elsewhere. Can anyone tell me the RPM range for cylinder cut-out?
  2. Beau

    Beau Senior Member

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    My 1998 820's cut out about 1000rpm? I've can't feel it in performance, though. I have had no problems running the no wake zones in along the intracoastal. NY to NC
  3. SomeDevil

    SomeDevil New Member

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    Thanks for that information, Beau.
  4. mapism

    mapism Senior Member

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    I can't answer your question on the exact RPM cutout.
    But I half recall to have been told by a MAN chap that it depends on both load and RPM, so you might be looking for a number which is actually variable.
    Any MAN service should be able to confirm you that, anyhow.

    BUT, and I'm mostly talking to Beau now, the 820hp version of the V10 (aka D2840LE401) was fully mechanical.
    And as all other MAN mechanical engines, it didn't have any cutout system.
    It is indeed rougher than the V12, and to a lesser extent also than the V8, particularly at low RPM.
    But that's the nature of the beast - nothing to see with cylinders cutout.
    Last edited: Nov 29, 2020
  5. Beau

    Beau Senior Member

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    Mapism

    I value your advice on a host of subjects, but, I believe, you will need to do some further reading on the 5 cylinder cutouts on the 10 cylinder 820's., otherwise my mechanics have been fibbing to me for the last 21 years. I believe there is a precise selection in determining which injectors get cutoff so the motors run very smoothly. Don't ask me how the motors do it. I just pay for the thing, and drive it once in a while. My pair run like 2 clocks at idle speed?
    Last edited: Nov 29, 2020
  6. Capt J

    Capt J Senior Member

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    No it won't hurt anything as long as you run it up to cruise a few times a day.
  7. mapism

    mapism Senior Member

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    I'd be glad to, if only I could find any references about it.
    Can you possibly enlighten me?
  8. Capt J

    Capt J Senior Member

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    The entire right bank shuts down and runs off of the left bank with the cylinder cutout. Usually cuts out around 1000 rpms, but is based on boost and done in the injector pump
  9. Beau

    Beau Senior Member

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    I was told that its not just one bank, but a selected 5, but I'm only passing on what I've been told
  10. mapism

    mapism Senior Member

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    Well it seems that we are all going by what we were told...
    Coming to think of it, years ago one dealer did mention to me the partialization on just one bank.
    But afterwards, I had a chance to speak with the chief engineer of the official MAN distributor, before actually buying a MAN-powered boat.
    He's the one who told me that there's no cutout on any mechanical engine.
    And since he's the person in charge of arranging training courses for the dealers' network, I took that as Gospel truth.
    But I never checked that first hand.

    BTW, I can't actually think of how to do that.
    What do you think, maybe checking the temperature with an IR gun pointed at each cylinder exhaust port?
    Or can you think of any other trick?
    I might give it a try on my V8s, the next time I'll run them.

    PS: ref. roughness at idle, Beau, I didn't say that the V10 aren't smooth, I did say they are rougher than the V12.
    Ever tried a V12 powered boat? You'd be surprised by how smooth those beasts are.
  11. SomeDevil

    SomeDevil New Member

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    As a newcomer to this forum, I want to thank you all for your responses so far. I will definitely try to do more reading on the subject as well. If I can pull it together, I think it'll be a great trip.
  12. Beau

    Beau Senior Member

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    "It is indeed rougher than the V12, and to a lesser extent also than the V8, particularly at low RPM.
    But that's the nature of the beast - nothing to see with cylinders cutout." What does that prior statement mean than??


    I believe I also read the cutoff in the manual as well as being repeatedly told. I just had my 2000 hour reconditioning and it was mentioned again. I'm texting my mechanic. I'll let you know.
    Last edited: Nov 30, 2020
  13. Beau

    Beau Senior Member

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    To confirm: 820's have the cut out. Run on cylinders 1-5. Governed by boost pressure.
  14. Alzira II

    Alzira II Member

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    So with the v-10s if you spend 6 hours idleing around the ICW sometimes there are not a lot of good options to clear then engines. Any solutions?
  15. Beau

    Beau Senior Member

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    I have not had a problem. The cutout actually closes the injectors, I believe, so there is no unspent fuel passing thru the cylinders and out the exhaust. Nothing is partially igniting because of low engine temps etc. Nothing to 'foul" the cylinders. The well lubed cylinders and valves are just moving up and down. I idle a fair amount, including at troll. My 820's have treated me well! If you have a concern and can't run them up for a few minutes (you don't have to hit cruise rpm), put them in neutral and run them up to 1200rpm for a minute or two. Alternatively, you can run a little faster on one engine at a time since "boost" is the operator. Takes a little rudder to control but is quite manageable. Put the tabs all they way down, if you think that will help create boost
    Last edited: Nov 30, 2020
  16. mapism

    mapism Senior Member

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    Well, just what I said, that in terms of smoothness the V12 is the smoother of the lot, followed by the V8 and the V10.
    And this is something I witnessed on several of engines, both mechanical and CRM.
    I'm not objecting to your perception that your engines run smooth, but trust me, you would feel some difference with the V12s (less so with V8s).

    I'm not insisting on my previous "no cutout" comment if you had an opportunity to double check that with your expert.
    I'll do the same with mine on the next opportunities, out of curiosity.

    But I can safely confirm you that there's no way injectors can be "closed", in your engines (as well as any other MAN pre-CRM).
    In fact, I've seen them removed and tested, and I also know first hand how the HP pump works.
    The injectors are very simple mechanical devices, which are not controlled in any way, other than by the fuel pressure.
    As soon as the pressure reaches the preset level (280 bar, as I recall), they pop open and the noozle sprays a burst of fuel - end of it.
    So, the only way some cylinder can be cut is by not sending any pressurized fuel to their respective injectors.
    I believe that this can only be handled by the HP pump - though at the moment I can't figure how exactly.

    On the other hand, you are certainly right in saying that there can't be any "unspent fuel" passing through the cylinders which are being cut, for the very simple reason that if their injectors would squeeze any fuel, there would be no cutout at all! :)
  17. Beau

    Beau Senior Member

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    Mapism, Give it a break. You gave incorrect INSISTENT info to a poster about the cutoffs. Stop speculating. I have already admitted I don't know all the processes....reciprocate. By the way, we shut off/close an open hose? By turning the spigot off. Just saying. As the post that follows demostrates, you have now injected wrong info into the minds of those 820 owners without purpose.
    Last edited: Nov 30, 2020
  18. motoryachtlover

    motoryachtlover Senior Member

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    I own 820’s as well and I was under the assumption that they did indeed have the cylinder cut out feature. May or may not be true. I will also confess that I don’t find my 820s very smooth at idle, but it is not an issue.
  19. Beau

    Beau Senior Member

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    You have cut outs or cut offs on the 820's according to the experts I have contacted and my reading, despite Mapism's insistence. What is is the lack of "smoothness" you are experiencing? I come in on one engine (alternating on trips) to stay under 6 knots in the no wake zone. They are a smooth as silk to me.
    Last edited: Nov 30, 2020
  20. motoryachtlover

    motoryachtlover Senior Member

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    I am not sure that I have cut outs or not. Just that I was told that by a few that should know. At idle if you stand on the dock next to the boat and you can see little ripples in the water coming off the hull. I also believe I have noticed what I consider more shaking of the engines than you would see with a gas engine, all of this is at idle. Above that she smooths out. I hope I have adequately described it.