Detroit Diesel 4-71 Engines

Discussion in 'Diesel Engines' started by brian eiland, Dec 23, 2013.

  1. brian eiland
    Joined: Jun 2002
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    brian eiland Senior Member

    A vessel has been brought to my attention that is equipped with twin 4-71 DD engines' It quoted as have 660 hp total,....330hp each.

    Is that even possible with these size engines??
  2. boatbuilder41
    Joined: Feb 2013
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    boatbuilder41 Senior Member

    I seen one advertised one time that claimed to have 300hp. Its very doubtful. The typical 4-71 dd naturally asspirated [ non turbo ] has between 90 and 120 hp. Depending on timing and injector selection. If at all possible it would be very very short lived. A typical 8v71 natural produces on average of 318 hp. So I would not think it to be possible and be reliable.
  3. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    That HP figure seems inflated a bit, possibly some ego stuff. A 284 CID diesel is certainly capable of 330 HP, though usually with "power adders". A typical 4-71 will have 160 to 200 HP. 330 HP is more in tune with an 8-71, not the 4-71 Driptroit.
  4. Çemberci
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    Çemberci Senior Member

  5. WestVanHan
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    WestVanHan Not a Senior Member

    IIRC the highest rated marine 6-71 TIB was 485hp, were tempermental and if used with any regularity at max hp they wouldn't last too long. As in hundreds of hours.

    So conceivably a 4-71 at the same boost and injection could put out about 325 hp,not sure I'd want to lean on the throttles all that much though....

    FF will know.

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    FAST FRED Senior Member

    Most DD 71 series engines are very long lived at 20-30 HP per cylinder ,40 HP is fine for a while but not as cruise.

    Once you get higher than that service life drops very fast.

    The sport fish killers with the almost 500hp 6-71 will cheer if ever seeing 1000 hours to rebuild .

    But they operate at FLANK to the fish area and back.
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