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  1. #1
    Bigcat1's Avatar
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    RXT-X at Elevation- top speed question

    Stock RXT-X with 18 hours

    Broken in according to the info I found on the forum
    GPS Top speed 63.4MPH.
    71 degree water temp, 75 degree air temp, 6 bars of fuel, light chop
    Elevation at 3800 Feet.

    From what I have seen this is about normal..Correct? Just hoping to get the correct base line before I start the mods!


  2. #2
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    Your density altitude is around 6000feet, so I'd say your speed is about right for the conditions.

  3. #3
    West Texas RXP skoepp's Avatar
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    what do you want to know about horsepower and elevation??. unfortunately i know alot about that subject. All my findings are hands on expericence so i know what i am talking about.

    I need to know your rpm and i assume you are stock machine.
    I also need to know your barametric pressure.
    You will see roughly 80 - 100 rpm differecence from sea level for every 1,000 ft of relative density altitude.

    I have run my skis with same setups at many different RAD so i can help you with your mods. If you are allways running at altitude then what works for the guys at sea level or at 500 ft will not work for you. Trust me. Also some mods that have helped me more with finding more horsepower dont really help the guy at sea level as much. Make that engine breathe more and get some good flow in the exhaust, not to mention more boost will help your elevation alot.

    But the prop and nozzle setup at sealevel will not work at all for you.

    Send me a pm and i will tell you what to do to your stock prop. There is more to it then just changing the trailering edge.
    Last edited by skoepp; 08-25-2008 at 06:41 PM.

  4. #4
    vidbuster's Avatar
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    True that-

    Lake Tahoe Density altitude yesterday was at 8900ft. I average 7300 rpms.

  5. #5
    Bigcat1's Avatar
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    Thanks Guys!
    I ride between 3800 and 5600 feet above sea level.
    At 3800 feet my RPM's have never been higher than 7600.
    Ralativly himitity was 22%
    BP we 29.71

  6. #6
    West Texas RXP skoepp's Avatar
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    Big Cat 1, i got your pm and will reply in pm to your needs.

    Here is some food for thought.
    This is going to blow your mind. I used your temp, pressure, altitude, etc and at 3,800 ft your RAD is 6,100 ft.
    At 5,600 ft. your RAD is 8,300 ft.

    With the 6,100 ft RAD I would guess that if your ski is running 8,000 rpm at sea level then at 6,100 ft RAD you should be off 500 - 600 rpm minimum without any tweaking. So if you say 7,600 rpm max then you are dead on. I would guess to say your are 5 to 7 mph off from what your ski would do at sealevel.

    I dont even want to figure what your hp would be at 8,300 rpm. that is insanely high with major loss.

    I got an idea what you need to do to your prop.

  7. #7
    Bigcat1's Avatar
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    Thank you very much for your help! Winter modding should be fun!

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