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  1. #1

    Default "Had my boat converted from a

    "Had my boat converted from a outdrive to a straight inboard and lost 500r's. Lost the 500r's under a load and on the curve (in neutral). Is it typical to lose this much RPM's from adding a transmision and a larger fly wheel? I realized I was going to loss R's but, not this much and NOT UNDER THE CURVE. Thanks, Charlie"

  2. #2
    Join Date
    Jul 2007
    Location
    North Charleston, South Carolina, USA
    Posts
    52

    Default "I don't understand what y

    "I don't understand what you mean by "under the curve in neautral", but the usually the loss in WOT RPMs can be cured with a lower pitch prop.

    Who determined what prop to use on the conversion and how was it determined?"

  3. #3

    Default Here are the specs: Engine: K

    Here are the specs:
    Engine: KAMD42B 230HP
    RPMS (under load):3300 /Before Conversion:3900
    RPMS (curve):3600 /Before Conversion:4100

    Thanks!

  4. #4

    Default "Hi Ronald, I have tried 4 di

    "Hi Ronald, I have tried 4 different props and the R's stay the same no matter what pitch we try. Also got the specs on the prop from the company that built the boat. Thanks for your reply!"

  5. #5

    Default "Sorry, under the cuve is WOT

    "Sorry, under the cuve is WOT in neutral."

  6. #6
    Join Date
    Apr 2006
    Location
    , Langkawi, Malaysia
    Posts
    5,750

    Default "That has probably to o with w

    "That has probably to o with weight and balance of the boat, and design.
    Please give some more info like boat type/size, props tested, gear ration etc.
    What has happened with speed?"

  7. #7

    Default The boat is a 35' Evans ba

    The boat is a 35' Evans bay boat. props test were 3 blade 20/15 20/17. 4 blade 18/14.5. Gear ration 2:1. Lost about 4knots and am cruising at 3000R's

  8. #8
    Join Date
    Apr 2006
    Location
    , Langkawi, Malaysia
    Posts
    5,750

    Default My guess You have installed a

    My guess You have installed a V-drive and 'tunnel'?

  9. #9

    Default "No, Just a straight shaft. ZF

    "No, Just a straight shaft. ZFgear box."

  10. #10
    Join Date
    Apr 2006
    Location
    , Langkawi, Malaysia
    Posts
    5,750

    Default "That indicates You might have

    "That indicates You might have moved the engine forward and totally changed the balance of the boat.
    I thing that might even have changed the shape of the hull, somewhat depending of new stringers and other reinforcements done. Your boat is hitting a 'max speed'. Too long to go into all, but have seen this before in similar set-up changes. The other alternative might be that when doing changes in the installation, You have made a 'mistake' somewhere in the diesel system, engine does not get enough diesel. Disconnect the return line, and check that diesel is flowing even at max obtained rpm. Or what about air? Any change when running with engine hatch open?"

  11. #11

    Default "Same when running hatch open.

    "Same when running hatch open. We did not move the engine foreward but, did raise the front of it. Thank You."

  12. #12

    Default Getting plenty of air. Tried

    Getting plenty of air. Tried it with filter off too.

  13. #13
    Join Date
    Apr 2006
    Location
    , Langkawi, Malaysia
    Posts
    5,750

    Default "Did You use a down-angle gear

    "Did You use a down-angle gearbox, or straight?
    What about oil-line/level in crank case? (Crank hitting/splashing oil)"

  14. #14
    Join Date
    Jul 2007
    Location
    North Charleston, South Carolina, USA
    Posts
    52

    Default "If it's lost RPM in neutr

    "If it's lost RPM in neutral, it's not the prop or position in the boat. As for the transmission, an outdrive has a transmission also. I can't see the transmission causing a big loss in RPM.

    Fuel problem, air problem, or something that was accidentally changed on the engine during the work. Governor, timing, etc."

  15. #15
    Join Date
    Jul 2007
    Location
    North Charleston, South Carolina, USA
    Posts
    52

    Default ""Did You use a down-angle

    ""Did You use a down-angle gearbox, or straight?
    What about oil-line/level in crank case? (Crank hitting/splashing oil)"

    That's a possibility if you angled the engine. I think there are Volvo specifications for this."

  16. #16

    Default Put the boat on a lift and lev

    Put the boat on a lift and leveled the engine and still same RPMS. Used a 8 degree down box.

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