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  1. #1
    Site Admin Green Hulk's Avatar
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    Spark radar graph - Stock VS V-Tech Tuned

    I set out this afternoon to do some acceleration testing on the Spark with the stock vs V-Tech tune. The first thing I figured out was it was near impossible to get a radar reading off of the Spark. I guess due to it's plastic hull. So, I obtained a small radar reflector of which I strapped around Josh's waist
    this helped some and was able to get one consistent reading out of every 4 or 5 runs.

    Another thing that made it hard to get consistent readings was with the tuned version the ski wanted to leap from the water and come unhooked. There is a substantial felt difference in power from tuned vs stock.

    One very important observation is the Spark hull has very little ventilation. This causes a rapid heat soak and timing pull back due to increased air intake temps.
    This Spark will pick up greatly with a true cold air intake system. I will see what I can figure out for an air intake and will go back for more radar testing

    you can see in the graph that the tuned Spark starts pulling away around 17 or 18 mph and maintains distance over the stock tune all the way thru top end.
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  2. #2
    GasResearch-VT.SE's Avatar
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    Nice way to show the results.

    So Josh was a power-ranger for a day ?


    It would pull 3 deg of timing minimum if enough engine noise was detected for sure, probably would need to be over 110 deg F air intake temps if using your 92 fuel.

    How can we make sure the ski stays in the water?

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    Site Admin Green Hulk's Avatar
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    Quote Originally Posted by GasResearch-VT.SE View Post
    Nice way to show the results.

    So Josh was a power-ranger for a day ?


    It would pull 3 deg of timing minimum if enough engine noise was detected for sure, probably would need to be over 110 deg F air intake temps if using your 92 fuel.

    How can we make sure the ski stays in the water?
    Yep! Josh had some fun today

    Maybe a bit of ride plate angle to keep the bow down would help, but that would also scrub some speed.
    Best solution is to have trim on the ski.... I have some ideas.

    Also, ski needs a grate badly!

  4. #4
    West Texas RXP skoepp's Avatar
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    Nice work Jerry and Josh.
    Some prop work might help that cavitation, you think?
    I would assume since lack of air into the hull that would mean its very sealed from water which I would think that was one of there main goals with the fun factor intended.

    I wonder were the best place will be to try to pull air from while still trying to keep water out,?

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    GasResearch-VT.SE's Avatar
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    patiently waiting for items to pop up in the store...

    Quote Originally Posted by skoepp View Post
    Nice work Jerry and Josh.
    Some prop work might help that cavitation, you think?
    I would assume since lack of air into the hull that would mean its very sealed from water which I would think that was one of there main goals with the fun factor intended.

    I wonder were the best place will be to try to pull air from while still trying to keep water out,?

    Jonatan played with the intake where the fire extinguisher is meant to be under the seat.... Don't think thats safe for roll over though.

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    Site Admin Green Hulk's Avatar
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    Quote Originally Posted by skoepp View Post
    Nice work Jerry and Josh.
    Some prop work might help that cavitation, you think?
    I would assume since lack of air into the hull that would mean its very sealed from water which I would think that was one of there main goals with the fun factor intended.

    I wonder were the best place will be to try to pull air from while still trying to keep water out,?
    Actually, there is no cavitation. The thing hole shots hard!

    I think a 3 blade impeller will help greatly with top speed. It's currently running a 4 blade.

  8. #7
    West Texas RXP skoepp's Avatar
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    Oh, OK,
    So it just launches out of the water.
    So some kinda trim would fix that.
    Needs a manual trim lever.

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    Site Admin Green Hulk's Avatar
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    Quote Originally Posted by skoepp View Post
    Oh, OK,
    So it just launches out of the water.
    So some kinda trim would fix that.
    Needs a manual trim lever.
    Exactly! manual trim lever is what's on my mind

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    Moderator Snoman's Avatar
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    Auto trim like R&D?????

  13. #10
    Site Admin Green Hulk's Avatar
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    Quote Originally Posted by Snoman View Post
    Auto trim like R&D?????
    R&D auto trim actually drops the nozzle when you turn the bars left or right.
    We need the nozzle down in a straight line on launch. Manual drop nozzle actuated by a lever would be ideal.

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