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Thread: VXR vs. SHO HP

  1. #1

    VXR vs. SHO HP

    Surprisingly the VXR NA engine is just as quick as the SHO engine in stock form. Amazing, right?
    Maybe and maybe not..
    Heres why they are virtually the same horsepower in stock form.
    Its all in the final compression ratio.
    The VXR engine is naturally aspirated and has 11.1 CR.
    The SHO is supercharged and has 8.5 CR.
    Final comp ratio on the VXR is of course 11.1
    Final comp ratio on a SHO engine is 12.1 with 6 lbs boost, and 13.1 with 8 lbs boost.
    So the SHO will make more power then correct?
    After subtracting the parasitic HP loss it takes for the SHO engine to spin the supercharger , we end up pretty much dead even on HP for both engines.

    The big difference will be when it comes to modifying the VXR NA engine..
    It will always have 11.1 CR, and therefore will be limited on its HP making capabilities.
    When we add bigger superchargers and more boost to the SHO engine, all we really do is increase the final compression ratio, which is always the way to huge horsepower.
    Example being, my 9.5.1 SHO engine with 20+ lbs of boost has a final comp ratio of close to 24.1
    No way the VXR NA engine will ever be able to compare to that.

    But just think, the VXR NA engine at 11.1, with a paltry 8 lbs of boost using a stock OEM wheel would have the same final CR of a SHO engine with an E1 wheel and 16 pounds of boost, and both would have a final CR of 17.1
    And with the final CR of the 8lb boosted and 16 lb boosted engines being identical at WOT, the 8 lb boosted engine would have less parasitic drag from a supercharger that wasnt huffing air but half as hard, and therefore create more HP.
    Not to mention the sprag life benefits of less boost.
    Something to think about when planning your next hi performance engine build..


  2. #2
    Kristian Keppel Waterholics's Avatar
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    Some good info here. I definitely think if its a mildly tuned ski then the vxr hands down but when we start looking at more agressive tunes I think the SHO engine fits the bill.

  3. #3
    My name is Sean and I am addicted to STXs smokeysevin's Avatar
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    what type of gas would you run with that though? in my 15f I am running 9.5 to 1 zx12r pistons and with the longer stroke it works out to ~12 to 1 so I can run 93 and get away with it, the 8 psi on the 11.1 to 1 pistons would take race gas right?

    Sean

  4. #4
    Good analysis. Having ridden some stock FZR's and my own VXR, I can tell you the VXR engine feels very strong. And the power feels linear from the bottom all the way to the top. I have a stock 15F KAW(thats 160 HP) and from just the feel of things, the VXR feels much muchh stronger than the 15F engine.

    It does sound like Jerry is going to find out just what the VXR can really do; he is the guy to do it. JB

  5. #5
    Quote Originally Posted by smokeysevin View Post
    what type of gas would you run with that though? in my 15f I am running 9.5 to 1 zx12r pistons and with the longer stroke it works out to ~12 to 1 so I can run 93 and get away with it, the 8 psi on the 11.1 to 1 pistons would take race gas right?

    Sean
    Intercooler effeciency plays a big role in if you NEED race gas or not...With that much compression you will make more horsepower with 109 fuel. If your going to push the envelope, why take a chance on fuel octane.
    IMO, race motors need race fuel, and 11.1 with 8 lbs boost gives overall CR of over 17.1... Thats a lot of squeeze goin on.. At least blend your 93 with 109 if you cant run 100%.
    50-50 makes 100+ octane, which is much better than just 93.

  6. #6
    My name is Sean and I am addicted to STXs smokeysevin's Avatar
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    The static ratio is 12 the actual will be much less with the cams I have, I was planning on blending it while i am tuning then slowly backing it off to see where it gets me, the idea of the boat was to be pump gas safe.

    Sean

  7. #7

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    VXR vs. SHO HP
    Surprisingly the VXR NA engine is just as quick as the SHO engine in stock form. Amazing, right?
    Maybe and maybe not..
    Heres why they are virtually the same horsepower in stock form.
    Its all in the final compression ratio.
    The VXR engine is naturally aspirated and has 11.1 CR.
    The SHO is supercharged and has 8.5 CR.
    Final comp ratio on the VXR is of course 11.1
    Final comp ratio on a SHO engine is 12.1 with 6 lbs boost, and 13.1 with 8 lbs boost.
    So the SHO will make more power then correct?
    After subtracting the parasitic HP loss it takes for the SHO engine to spin the supercharger , we end up pretty much dead even on HP for both engines.

    The big difference will be when it comes to modifying the VXR NA engine..
    It will always have 11.1 CR, and therefore will be limited on its HP making capabilities.
    When we add bigger superchargers and more boost to the SHO engine, all we really do is increase the final compression ratio, which is always the way to huge horsepower.
    Example being, my 9.5.1 SHO engine with 20+ lbs of boost has a final comp ratio of close to 24.1
    No way the VXR NA engine will ever be able to compare to that.

    But just think, the VXR NA engine at 11.1, with a paltry 8 lbs of boost using a stock OEM wheel would have the same final CR of a SHO engine with an E1 wheel and 16 pounds of boost, and both would have a final CR of 17.1
    And with the final CR of the 8lb boosted and 16 lb boosted engines being identical at WOT, the 8 lb boosted engine would have less parasitic drag from a supercharger that wasnt huffing air but half as hard, and therefore create more HP.
    Not to mention the sprag life benefits of less boost.
    Something to think about when planning your next hi performance engine build..

    thats spot on . those paragraphs are the best bits of info i ve read on any forum. i owe a 2011 vxr would i better working on it or buying a fzr cheers

  8. #8
    rick xp's Avatar
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    Why not throw 10.5:1 Compression pistons in a FZR and you just about have exactly the same engine as the VXR. Six of one and half a dozen the otherr.

    Where you will see gains between the FZR and VXR maybe in the weight??

  9. #9
    RichieFZR's Avatar
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    Quote Originally Posted by rick xp View Post
    Why not throw 10.5:1 Compression pistons in a FZR and you just about have exactly the same engine as the VXR. Six of one and half a dozen the otherr.

    Where you will see gains between the FZR and VXR maybe in the weight??
    Weight.

  10. #10
    Quote Originally Posted by rossnemo View Post
    Surprisingly the VXR NA engine is just as quick as the SHO engine in stock form. Amazing, right?
    Maybe and maybe not..
    Heres why they are virtually the same horsepower in stock form.
    Its all in the final compression ratio.
    The VXR engine is naturally aspirated and has 11.1 CR.
    The SHO is supercharged and has 8.5 CR.
    Final comp ratio on the VXR is of course 11.1
    Final comp ratio on a SHO engine is 12.1 with 6 lbs boost, and 13.1 with 8 lbs boost.
    So the SHO will make more power then correct?
    After subtracting the parasitic HP loss it takes for the SHO engine to spin the supercharger , we end up pretty much dead even on HP for both engines.

    The big difference will be when it comes to modifying the VXR NA engine..
    It will always have 11.1 CR, and therefore will be limited on its HP making capabilities.
    When we add bigger superchargers and more boost to the SHO engine, all we really do is increase the final compression ratio, which is always the way to huge horsepower.
    Example being, my 9.5.1 SHO engine with 20+ lbs of boost has a final comp ratio of close to 24.1
    No way the VXR NA engine will ever be able to compare to that.

    But just think, the VXR NA engine at 11.1, with a paltry 8 lbs of boost using a stock OEM wheel would have the same final CR of a SHO engine with an E1 wheel and 16 pounds of boost, and both would have a final CR of 17.1
    And with the final CR of the 8lb boosted and 16 lb boosted engines being identical at WOT, the 8 lb boosted engine would have less parasitic drag from a supercharger that wasnt huffing air but half as hard, and therefore create more HP.
    Not to mention the sprag life benefits of less boost.
    Something to think about when planning your next hi performance engine build..
    With the conclusion "dead even on HP for both engines", the FX HO (same 1.8 NA Engine with 11:1 CR on the VXR, weight 794 lb) should be faster than FX SHO (1.8 SC Engine with 8.6: 1 CR, dead even hp for both engine, weight 829 lb) in terms of acceleration and top speed. FX HO and FX SHO are both NanoXcel Hull with same length. So with the conclusion "dead even on HP for both engines" -- > SHO is less reliable, heavier and slower but more expensive. Why the hell people buy FX SHO if it is less reliable, less efficient, heavier and slower but more expensive.

    http://www.greenhulk.net/forums/show...ight=SHO+vs+HO

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