Detroit Diesel 4-71 Engines

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

  1. brian eiland
    Joined: Jun 2002
    Posts: 4,788
    Likes: 157, Points: 73, Legacy Rep: 1903
    Location: St Augustine Fl, Thailand

    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
    Posts: 159
    Likes: 4, Points: 18, Legacy Rep: 56
    Location: panama city florida

    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
    Posts: 19,133
    Likes: 472, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    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
    Joined: Apr 2007
    Posts: 127
    Likes: 6, Points: 0, Legacy Rep: 133
    Location: Istanbul/Turkey

    Çemberci Senior Member

  5. WestVanHan
    Joined: Aug 2009
    Posts: 1,374
    Likes: 56, Points: 0, Legacy Rep: 746
    Location: Vancouver

    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.
     

  6. FAST FRED
    Joined: Oct 2002
    Posts: 4,519
    Likes: 109, Points: 63, Legacy Rep: 1009
    Location: Conn in summers , Ortona FL in winter , with big d

    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.
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.