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De-Tune an engine for better fuel economy?

Discussion in 'Technical Discussion' started by Rande Schuck, Apr 14, 2016.

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  1. Rande Schuck, Apr 14, 2016
    #1
    Rande Schuck

    Rande Schuck New Member

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    Can I de-tune a 12v92ta and get better fuel economy??
    Last edited by a moderator: Apr 14, 2016
  2. Capt J, Apr 14, 2016
    #2
    Capt J

    Capt J Senior Member

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    You can but that also requires re-propping the vessel and smaller injectors, and re-setting the rack. What you're going to spend to do so will cost a lot more than any fuel costs savings generally. You're better off running them at 1000 rpms (hull speed) and then running them at cruise for 30 mins every 6 hours (or less)
  3. Rande Schuck, Apr 14, 2016
    #3
    Rande Schuck

    Rande Schuck New Member

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    Thank's I will be running lots of hr per week about 72 hr it will be at 8 knots I'll kick it up 30 mins twice a day and at night I will be on sea anchor for 12 hr most likely with one engine always running in neutral at idle 3 hr on 3 hr off. I'll be covering the same 500 nautical miles each week .
    I assume I should only kick it up to 1800 rpm or wherever the turbos kick in.
  4. Capt J, Apr 14, 2016
    #4
    Capt J

    Capt J Senior Member

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    No 1900 rpms, you want to get EGT up to burn out the slober out of the airboxes and turbos. I will usually bring them up to 1300-1400rpms where the turbo's start to turn and you see the slober burning off for a few minutes till the exhaust clears up, then bring them up the rest of the way.

    Why are you leaving one running all night long, you don't have a generator to keep the batteries charged? If you have a generator and battery charger and no other need to keep the running I'd shut the mains down. It's best to leave the same engine running and alternate to the other one the next night....oil temp stays up, water temp, etc. Letting them idle all night with no load is not good for them at all.
  5. Rande Schuck, Apr 14, 2016
    #5
    Rande Schuck

    Rande Schuck New Member

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    I guess your right I just had a bad experience about 15 years ago off of Baja Mx. I shout down and the next morning now go could not find the pronlemo knew it was elect, but sat for 2 days and lucky a sail boater came along and between all of us we fond the problem.
  6. g collis, Apr 15, 2016
    #6
    g collis

    g collis Member

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    Shooo, that is really tough on an engine idling like that. In addition to Capt J's good advice, I'd also suggest changing your oil twice as often as you currently do. A lot of garbage building up in there with long idle times.
  7. Lepke, Apr 17, 2016
    #7
    Lepke

    Lepke Member

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    Running at idle for long hours can shorten the life of sleeves and rings. Less oil getting to the top, less slinging of oil. But, long idle is less damaging than high turbo heat. Separate banks of starting batteries will solve the emergency start issue. I run 2 starting banks on each main. Probably overkill, but I anchor for long periods in very remote places.
  8. Pascal, Apr 18, 2016
    #8
    Pascal

    Pascal Senior Member

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    I can't imagine any decent boat not having a dedicated bank for each engine and Genset plus a house bank. Set up this way means the odds of a dead boat are nil.

    As long as th engines are running at operating temperature, there is no reason not to slow down to hull speed or less if you want to save fuel. Then yes spool them up for a while to clean them up. Better this way than spending lot money detuning them.
  9. olderboater, Apr 18, 2016
    #9
    olderboater

    olderboater Senior Member

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    Address the underlying issue, not the symptom. Have the right electrical setup to protect against such events as you experienced.