View Poll Results: Sound suppression hindering performance?

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  • Yes, 100 RPMs or more.

    7 38.89%
  • No, keep looking elsewhere.

    11 61.11%
Results 1 to 9 of 9
  1. #1
    JFizzleJR's Avatar
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    Sound suppression hindering performance?

    Does anyone think it's plausible that the factory Yamaha sound suppression system being hooked up to my conversion box is causing a loss of performance? I'm down 500 RPMs and exploring all avenues. I have the feeling Mike (addicted) might have some good input on this. Anyways, any thoughts/ideas/suggestions are welcome as always.


  2. #2
    cheatin' piston popper addicted's Avatar
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    I highly doubt it. And if it does, it's not 500 rpm's worth. did you see Danny's thread with the flow rates of the gpr and conversion exhaust parts?

    What prop are you running? I know my 14/20 dynafly is only getting 7700 rpm for me. also what nozzle so you have?

  3. #3
    Hydrotoys's Avatar
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    Fizz,
    would it be that hard to remove it and test without it?

    If yes, then you have an answer. If no, move along. I know you are just trying to save some time, but where ever your 500r's are hiding are going to just take trial and error.

  4. #4
    JFizzleJR's Avatar
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    14/20 DF pitched to 16/22 per Mark's suggestion . B-kit, XS IC, 4" front air intake, RIVA ECU.. Seadoo pump with an out of the box 15/20r turns approximately the same RPMs. Swapped the intake manifold and I saw a 200 RPM gain (was down 700+). Next is to swap superchargers (even though the slip was set perfect 1 riding hour ago).

  5. #5
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    The sound suppression would have to be blocked for you to see a drop of 500rpm...Check your SC slip...

  6. #6
    Vern's Avatar
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    500 rpm is a lot ... any chance your motor is an '04 and had the knock resistor removed? What is your boost level? Fueling and AFR good?

  7. #7
    96yam701's Avatar
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    the poll was miss leading,

    yes sound suppression does hinder the engine's performance that is why race cars dont have mufflers.

    but if you randomly lost 500 RPMs i would doubt removing the water box would help, and if it does your probably harming the enigine even more. by running it without fixing the real problem.

  8. #8
    JFizzleJR's Avatar
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    I never lost these RPMs. They weren't there to begin with. I've been chasing possibilities left and right trying to get my setup running as strong as others get for baseline numbers. Strictly RPMs, not speed. Engine first, hull later is how I'm attacking it.

  9. #9
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    Whats your AFR? You could be running too cold, thus running fat...

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