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  1. #1

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    Is myboat too cool?

    My boat is set up for hook-up except for jims plate. Hits the mid 67's when it is flat and otherwise always has power.

    When I stop and feel the exhaust it is not hot at all - i can put my hand on it and keep it there without a problem.

    Water is about 78

    Would dumping the 2nd/3rd cooling line help raise exhaust temp and give more power on my boat?


  2. #2
    New ski! Markb47's Avatar
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    Yes it would

  3. #3
    YudLuz2's Avatar
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    It would raise pipe temp, but would hurt performance.

  4. #4
    flyboy's Avatar
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    Quote Originally Posted by YudLuz2 View Post
    It would raise pipe temp, but would hurt performance.
    please explain, since you know we all do this. What has your testing shown?

  5. #5
    Hydrotherapy's Avatar
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    i tested with dumping #3 only over rear as i have stock cut head and not able to do #2 as well,i found an average of 6 degree temp raise on pipe surface with water dumped across ten marked points on the U section down to bottom of stinger,
    ran stock set up for one very long pass and recorded temps and rpm then switched over to water dump and repeated same long wot pass,no rpm gain but it will help as the extra heat will increase the exhaust wave in the the pipe...
    i was happy to leave it dumping as i'm sure a few of these little things will add upto a small gain along the line..
    you guys might see rpm gain as you ride in warmer waters and air temp..

  6. #6
    Quote Originally Posted by Hydrotherapy View Post
    i tested with dumping #3 only over rear as i have stock cut head and not able to do #2 as well,i found an average of 6 degree temp raise on pipe surface with water dumped across ten marked points on the U section down to bottom of stinger,
    ran stock set up for one very long pass and recorded temps and rpm then switched over to water dump and repeated same long wot pass,no rpm gain but it will help as the extra heat will increase the exhaust wave in the the pipe...
    i was happy to leave it dumping as i'm sure a few of these little things will add upto a small gain along the line..
    you guys might see rpm gain as you ride in warmer waters and air temp..
    I have my stock hose routing and milled head as well and notice rpm drop off as the air & water temps heat up...

  7. #7
    YudLuz2's Avatar
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    Quote Originally Posted by flyboy View Post
    please explain, since you know we all do this. What has your testing shown?

    Loss of peak rpms, greater chance of deto, higher temps in the engine compartment and more power loss on a heat soaked motor.
    Its a water cooled tunned pipe, not a factory dry pipe that needs heat.

  8. #8

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    Quote Originally Posted by YudLuz2 View Post
    Loss of peak rpms, greater chance of deto, higher temps in the engine compartment and more power loss on a heat soaked motor.
    Its a water cooled tunned pipe, not a factory dry pipe that needs heat.
    I bet everyone will be changing there setup before long.

  9. #9
    Pistonwash's Avatar
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    Quote Originally Posted by jcorallo View Post
    My boat is set up for hook-up except for jims plate. Hits the mid 67's when it is flat and otherwise always has power.

    When I stop and feel the exhaust it is not hot at all - i can put my hand on it and keep it there without a problem.

    Water is about 78

    Would dumping the 2nd/3rd cooling line help raise exhaust temp and give more power on my boat?
    The reason why most of the modded skis dump the #3 is because of too much pressure mounting up within the head and pipe. We've seen water leaks (Fernando) with too much pressure in the OEM head and leaking through the gasket.

    Lowell recommends this method with his port work...Tommy Jordan recommends it with his skis and so does Me.

    Plus, it helps the rubber block-off in the stinger not bust open while using the jetworks mod.

    Whatever gains you may think you are getting with adding piston crown temps via the exhaust don't translate into real power. Heat soak is a killer for an engine...in the summer you do what you can to lower temps not raise them.

    5% power loss after an engine warms up is not uncommon and the only real cooling you have is fuel and water.

    Unless your engine is modded and has an extra amount of water pressure, you should be thankful for the coolness you can achieve imo.

    Cool is good in summer.

  10. #10
    dlamazing's Avatar
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    Originally Posted by YudLuz2
    It would raise pipe temp, but would hurt performance.

    can you please explain in more detail how do you have hoses routed and what would be the downside about one set up and the up of the other setup i have a plug on the pipe and the other inlet to cyl#1 cyl#2 out and #3 out and jetworks mod i use to have it factory setup how riva has it routed on the diagram for the riva heads always got good numbers like this!! but this blocking one inlet and dumping 2,3 i havent gotten no good #s with this i think the motor still runs the same temp pipe does get hotter so i dont know let me know what you think thnx

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