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Thread: Top Speeds...

  1. #1

    Top Speeds...

    I've seen a few posts similar to this one, but thought I'd post it again and see what everyone thinks..

    I've got a 2007 F-12x that I've just recently taken out of the boat yard (was stored for about 2 years). When I took it out I changed the oil, checked idle speeds, put new plugs in, fresh gas, etc. since it had been stored for so long (it has about 40 hours on it).

    It seems to run just fine, but I can't get it above 55 mph. A couple of years ago I was getting it up to 65 without any problems on calm water. Again, the engine seems fine and it runs smooth, just can't get it going as fast as it used to.

    If anyone has any ideas of things to look for / check, I'd really appreciate it. Thanks.


  2. #2
    NOIDEA's Avatar
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    What is your rpm at WOT?

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    NOIDEA's Avatar
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  4. #4
    I did that test... There are two hoses coming off of the WGS, one of them is grey, and the other one is black. I could not blow into the black hose when the engine was off or at idle. I could blow into the grey hose when the engine was off. I haven't yet tried blowing into that hose at idle. I'm not too sure what this means though?

  5. #5
    Sorry I forgot to add in there that I could blow into the grey hose when the engine was at idle.. So basically - I can't blow into the black hose while the engine is off or at idle, and I can blow into the grey hose when the engine is off or at idle. Thanks.

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    NOIDEA's Avatar
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    Its a bit confusing.... So you can blow through the pipe that comes from the turbo to the WGS at idle? Next in line to check would be the waste gate actuator. What is your rpm at wide open throttle?

  7. #7
    No... I think that is the hose I can't blow through at idle or when the engine is off. It goes from the WGS to a T connection, which is then connected to the waste gate actuator. I guess the other hose (the grey one) is the wastegate pressure relief hose, that I can blow through when the engine is off or at idle (based off of the maintenance manual that I have). Hopefully that makes sense, sorry for the confusion.

  8. #8
    And I don't know the rpm at WOT... It's been raining here the past two days - I'll try and get it out on the water tomorrow and give you an answer.

  9. #9
    jlfx car audio's Avatar
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    Start with ur rpm . if its 6000-6200 ur right where a stock ski should be .
    If its lower then unhook ur black hose from wgs and run ski . it should scream for about 15 sec . slowly build up speed don't just nail it . progressively give it gas until u get on plain then watch ur rpms u should hit 6300+ then ski will cut HP/rpm . this will confirm ur turbo and high pressure couplings r still up to par .
    Do those 2 checks before u start digging to deep .
    For other peoples past experience the f12x stock only does 57-59mph (not to say that's what shows on the dreamOmeter tho) if ur rpms r above 6k I might think u may just have some buildup and possibly corossion on the speedo wheel itself

  10. #10
    Cool - hopefully the weather is good tomorrow and I can give that a shot. Thanks a lot for the input.

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