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  1. #1

    Question Water Pressure as it relates to Motor Height???

    Ok, the outboard is mounted in the 3rd mounting bracket hole. The anti-ventilation plate is 3.5" above the bottom of hull (it's a stepped hull).
    When at WOT (at full trim), the water pressure is 16 psi. If I tap the trim down switch once, the water pressure increases to 18 psi.
    I am trying to maximize boat performance and would like to raise the motor (either on the transom or via a jackplate). But, I am concerned that the water pressure will drop further.
    Looking for advice on how to raise motor and still keep maximum water pressure.
    Thoughts?
    dh
    Last edited by darleyhavidson; 09-20-2019 at 08:01 AM.

  2. Member lpugh's Avatar
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    May 2009
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    Sacramento Ca
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    #2
    Need more information:
    Serial number of motor
    Specific motor
    rev limiter
    Which gearcase, side picture would help, Does it have water inlet holes in the nose of the lower unit
    Specific boat
    Specific prop
    Setback
    Jack plate
    Base line performance information as well
    How's it loaded
    Top speed GPS
    Top rpm at WOT (digital tach or smart craft)
    Holeshot rpm when the bow lifts up before nose over
    Last edited by lpugh; 09-19-2019 at 08:54 PM.
    Thank You Leon Pugh

  3. #3

    Question

    Quote Originally Posted by lpugh View Post
    Need more information:
    Serial number of motor: 0T483495
    Specific motor: 2002 Optimax 225
    rev limiter: 5750 Max RPM
    Which gearcase, side picture would help, Does it have water inlet holes in the nose of the lower unit: It has the 4 inlet ports on nose cone as well as the normal inlet ports on side of lower unit.
    Specific boat: 2002 Ranger 620VS (fuel tank is NOT located in bow)
    Specific prop: Tempest Plus 21P
    Setback: Integrated into transom on this model boat
    Jack plate: No Jack plate
    Base line performance information as well
    How's it loaded: Kicker Motor, trolling motor, 4 batteries, 47 gallons of fuel, 2 adults, full tourney load.
    Top speed GPS: 51.5
    Top rpm at WOT (digital tach or smart craft): 5640
    Holeshot rpm when the bow lifts up before nose over: 4000 RPM
    Requested info listed above. Thank you for any insight you can provide.

    dh
    Last edited by darleyhavidson; 09-20-2019 at 08:02 AM.

  4. Member
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    #4
    I don't think you can raise the motor any higher, without dropping under a safe, sufficient water pressure.



  5. #5
    Quote Originally Posted by Savage View Post
    I don't think you can raise the motor any higher, without dropping under a safe, sufficient water pressure.
    Would setting the motor back with a 6" jack plate help with the water pressure; as the lower unit would be in a little "cleaner" water?

  6. Member
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    Bentonia, MS 39040
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    #6
    Any setback might assist
    Ron Fears
    Stroker/300XS
    1E003823

  7. Member
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    #7
    Quote Originally Posted by darleyhavidson View Post
    Would setting the motor back with a 6" jack plate help with the water pressure; as the lower unit would be in a little "cleaner" water?
    Doubtful that a jackplate will make a difference with water pressure on your boat.



  8. #8
    Quote Originally Posted by Savage View Post
    I don't think you can raise the motor any higher, without dropping under a safe, sufficient water pressure.
    The original lower unit did not have the 4 ports in the nose cone and the max water pressure was 15 psi at WOT. The powerhead never overheated. What PSI range is considered sufficient at WOT?

  9. Member
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    #9
    Quote Originally Posted by darleyhavidson View Post
    The original lower unit did not have the 4 ports in the nose cone and the max water pressure was 15 psi at WOT. The powerhead never overheated. What PSI range is considered sufficient at WOT?
    15 PSI



  10. #10
    Quote Originally Posted by Savage View Post
    15 PSI
    15PSI is not much of a range. Is it the minimum WOT PSI for all 3.0L outboards?

  11. Member
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    #11
    Quote Originally Posted by darleyhavidson View Post
    15PSI is not much of a range. Is it the minimum WOT PSI for all 3.0L outboards?
    Yes, anything higher is a bonus.