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  1. #1
    Ridin' the Rancocas 04RXP22's Avatar
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    Low RPMS....Now what?

    Ok.... Here's the deal.

    At the end of last summer I was running a S1 at 73.6MPH/8100RPM. At that time I had the following mods: 14/19R, Filled holes, rev. bucket mod, intake grate, sponsons, catch can, wedge, OPAS block offs, Flowrites, and riva front intake.


    Over the winter I added the following: XS IC, boost gauge, Riva Stage 2 wheel, metal washers, new needle bearings, front motor mount, 15/20R, X-BO block offs, R&D Steering nozzle, Adjustable venturi nozzle, iridium plugs, IC filter, Thru-hull exhaust, Flared J-Pipe, and gutted waterbox.

    Here's what's going on.

    On the first couple of rides this year I had a few problems.
    -I didn't seat my J-pipe right on re-installation. There was exhaust smoke coming from the V-band clamp. I fixed that easily.
    -The next problem was with the XS IC. The one that I installed had a leaking core. It was causing the engine compartment to fill with steam. I bought a new XS and now that problem is no longer.

    Now to the RPM issue.

    A week and a half ago I went out riding to test the new XS and everything seemed to be running better. However I was only turning 7650-7750 RPM and I was about 7.8# of boost. I didn't have the GPS with me that day. I had the 81mm ring in the nozzle.

    Today I ran on about 2/3 tank of gas. I put the 83mm ring on. I was only turning 7400-7500 RPM & about 6.5# of boost. The top speed on the GPS today was only 70.5MPH. With the larger ring the RPMs when down!!!



    Please someone help.


  2. #2
    Site Admin Green Hulk's Avatar
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    boost leak

  3. #3
    Site Admin Green Hulk's Avatar
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    ..... also, was your impeller new out the box? If it was used chances are someone could have added some pitch to it and it's just too much pitch for your setup.

  4. #4
    Ridin' the Rancocas 04RXP22's Avatar
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    Quote Originally Posted by Green Hulk View Post
    boost leak
    I will check all the possible areas. Would that cause me to run at such low RPMs.

  5. #5
    Ridin' the Rancocas 04RXP22's Avatar
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    Quote Originally Posted by Green Hulk View Post
    ..... also, was your impeller new out the box? If it was used chances are someone could have added some pitch to it and it's just too much pitch for your setup.
    I bought it used from Fizzle. He had posted it as untouched, but after I just contacted him. He said he may pitched it -2.

  6. #6
    West Texas RXP skoepp's Avatar
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    Quote Originally Posted by 04RXP22 View Post
    I bought it used from Fizzle. He had posted it as untouched, but after I just contacted him. He said he may pitched it -2.
    If he pitched it - 2 mm then its not your prop. Boost leak.

  7. #7
    Site Admin Green Hulk's Avatar
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    Quote Originally Posted by skoepp View Post
    If he pitched it - 2 mm then its not your prop. Boost leak.
    i agree

  8. #8
    Ridin' the Rancocas 04RXP22's Avatar
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    Ok... Time to re-seal everything.

  9. #9
    Moderator DrewNJ's Avatar
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    Is there anyway to pressure test the the system on the 4-tec to look for leaks?
    I remember with the old Saab's that we used to be able to do some blocking off and pressurize the system to look for leaks, but that was obviously different. Just curious.
    Doug

  10. #10
    Ridin' the Rancocas 04RXP22's Avatar
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    Just got done re-sealing everything.

    I found the leak..... I guess it is pretty obvious that a misplaced, half falling off kids room would cause a pretty major boost leak.

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