Hammerhead 300hp Chevy 6.5 L supercharged motors

Discussion in 'Diesel Engines' started by Carl Dalmas, Mar 20, 2021.

  1. Carl Dalmas
    Joined: Mar 2021
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    Carl Dalmas Junior Member

    Hi I had a sea ray 340ec classic empowered her with these engines on shafts thru zf63a boxes
    My question is can I link these motors to Yamaha sterdrives and will they take the torque
     
  2. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    300HP is not that much. The Yamaha sterndrives are equivalent to a Mercruiser Alpha, which are fine with the new 5.7 at 315 HP.
     
  3. Carl Dalmas
    Joined: Mar 2021
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    Carl Dalmas Junior Member

    Hi
    Thanks for your reply
    These engines make massive torque 680nm @ 1.5 rpm

    And they use very little fuel !
    5 gallons per hour @ 22knts
    BOTH engines
    flat water were figures a we got with full fuel tanks
    and water
    As for the yamaha drives they are totally different to alpha as they are hydraulic gearboxes and have 12 clutch plates on the drive
    The alphas are dog gear clung ! Change
    These engines destroyed alphas
    They used Conrad drives because the torque was too much they made a 400hp as well
    These engines were designed as a drop in exchange for 454 motors guzzlers @ 35 gallons per hour !
     
  4. gonzo
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    gonzo Senior Member

    I have never seen Yamaha sterndrives with hydraulic gearboxes. All the ones I rebuilt or worked on had dog ear clutches. Is there a hydraulic pump in the lower unit to operate the clutches?
     
  5. Carl Dalmas
    Joined: Mar 2021
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    Carl Dalmas Junior Member

    Hi
    Where the dog gear goes on a normal one they have two crown gears forward and reverse and 6 clutch plates on each side
    Hydraulic pump
    They need regular oil change but when right
    They change gear like silk
    Problem is yamaha stopped making them as they were two expensive to make
    And spares are hard to come by now and very expensive
    They can be prone to slipping after many hours
    Theres a small hidden gorse wire mess filter hidden at the top that can get blocked with swarf off gears over time
    Alot off jap fisherman all use them ! Hydro glide ! Think they are called on yanmar 420sti engines or the 6lyp
    Ref Hammerheads are not stock chevy 6.5 motors
    They run lower comp pistons and standyene 4 injection pumps with very special set up
    Inlet manifold is custom with a massive bronze charge cooler in the inlet housing
    with a blower 5.7 ltr on top !
    Cold saltwater is pumped through gives a big bang ,with very cold compression .
    and very little fuel injected marine injectors
    no turbos anywhere
    Custom exhausts aluminium ceramic coated,
    with stainless risers .
    two separate salt water returns to riser so no corrosion ,can happen
    And hydrualic lock engine up
    The blocks were specially made down the gm line with bigger oil galleries and other modes
    Under contract with GM
     
  6. Carl Dalmas
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    Carl Dalmas Junior Member

  7. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    I see. They are set up with a regular inboard transmission and a jack shaft.
     
  8. Carl Dalmas
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    Carl Dalmas Junior Member

    Were in my sea ray 340ec till vandals broke in it then set it on fire i just cut the boat up and salvaged them out off her the haylon saved them
     
  9. Carl Dalmas
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    Carl Dalmas Junior Member

    What other outdrives could I fit these engines to?
    and what bell housing would I need to do job
    Been told these will destroy volvo outdrives make too much torque
    They did do some with conrad out drives ?
     
  10. gonzo
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    gonzo Senior Member

    Those engines don't have more HP or torque than many of the Volvo diesels and the outdrives handle them without problem.
     
  11. Carl Dalmas
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    Carl Dalmas Junior Member

    The merc diesel bravo 3 were not out! when these engines
    came out in 2005 with diesel gear ratios
    But dont know bell housing needed for block match and where from
     

  12. Carl Dalmas
    Joined: Mar 2021
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    Location: Uk

    Carl Dalmas Junior Member

    Volvo diesels early ones were rpm @ 2800 max tam61a 306 hp
    The hammer's were tested on most outdrives at time and destroyed them thats why they used conrad
    But there was no duo prop available at that time
    And outdrives have moved on
     
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