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  1. #1
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    Question Prop slip on overhub prop related to no exhaust relief?

    Vegas XT/ 225 Looper turning 28P Mazco RE4 @ limiter (6700) at only 83 mph......no exhaust relief (stock). Is the overhub exhaust causing all this slip?? Over 16%!!!???
    B.MAC
    Last edited by B.Mac; 09-06-2003 at 03:15 AM.
    Jesusfreak of the
    Sunshine Syndicate
    http://www.harvesthousejax.org
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  2. #2
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    Nope. It's gotta be the prop or setup, assuming the guages are right.
    Membership upgrade options: http://www.screamandfly.com/payments.php

  3. #3
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    Sep 2002
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    Loch Erin, Irish Hills Area, SE Michigan
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    I run about 15% slip with a 28" chopper. Play with your jack height. Here's my experiences with that very fine range of height adjustment , starting with low and working up higher:

    1. low slip, but lots of drag. Rpm's down, but speed is affected. 5 mph slower than potential. Positive trim offers FLYING bow lift.

    2. Speed increase, rpm increase. Aha! The sweet spot.

    3. Speed about the same, but RPM's increase. High slip. Trim less effective, big rooster tail.

    4. Speed the same, slip and RPM are high. Motor is crabbing. Losing bow lift bite. Risk of blowout (needless to say.)

    Play around with it.

    The over hub exhaust only affects holeshot. A surfacing prop is only half in the water. It's all in the setup. Don't use any more trim than you need. the Vegas will still fly even with a flat running attitude. Use only as much trim as needed to keep it on the pad, maybe a tad bit more. And BE SAFE!
    '89 Hydrostream Vegas XT, '90 Merc 2.4 Bridgeport PCU EFI
    My YouTube videos________My Flickr photo gallery
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  4. #4
    Join Date
    Apr 2001
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    Carrollton, Tx
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    Setback

    Do a seach on Nosubforcid. You will find a lot of info on your boat.
    Heres a couple of quotes. If your lookin for top speed only, go with more setback,3 blade in cleaner water.

    Mr Baker told me 10-14 inches of setback. Nosub told me 10.


    On an XT a shooter or trophy will run the fastest if the motor is bolted right to the transom in the top hole without a nosecone. If you go back top speed with the four blades drops. If you don't go back at least 8" then most three blades won't be able to carry the bow without running the gearcase real low or using alot of positive trim. So if you are between right on the transom and 8" back nothing really works very well on these boats. If you are setback and have water pressure running without a low water pickup your gearcase is too deep in the water. With that setup a raker will carry the bow like nuts you aren't ever going to go very fast.


    I spent part of Saturday afternoon dialing in a 1990 Voyager with a 2001 Johnson 225HO. Motor has rev limiter disconnected, heads cut for 94 octane, Boyesen reeds on stock cages, 200 XP louvers in the hood, and exhaust relief holes drilled otherwise completely stock. Best top end runs were 91-92 mph gps turning a 29" Hoss Triton 6850 rpm. The motor is ten inches back on a Detwiler jackplate and still pulls a skier decently with a 25" Shooter.
    If you go out solo, throw 100lbs of something on the passenger side.
    If you don't have Hyd. steering get it. You'll see why the first time you run it. (You can use a smaller steering wheel)
    If you run over 28P, wire in a neutral start bypass switch. It will help the LU

    Best I can suggest
    Good Luck and play it safe

    Sure miss Nosubs postin Where hell are you man??????

  5. #5
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    Sep 2002
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    blow out

    B Mac,

    look at that torque tab, maybe to thick, causing water dam to the prop.

    Ken
    Ken Cook
    941.628.8250
    1966 Formula Jr (power coming)

  6. #6
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    I was kind of wondering about that. His tab looks very short and quite wide. I have a land & sea rivet-on tab that is much narrower, but longer. I just got finished smoothing it over with marine tex and re-painted my gearcase. They say that it makes no performance difference, but I'll see for myself soon enough. I'll post numbers tomorrow.
    '89 Hydrostream Vegas XT, '90 Merc 2.4 Bridgeport PCU EFI
    My YouTube videos________My Flickr photo gallery
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  7. #7
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    B.Mac

    Take a look at www.randrpropshop.com then go to the tips page and read it they do a better job of explaining your problem and the fix then I can.
    The wedge your pushing in front of your prop is killing your handling and speed.
    Then get a Bob's weld on tab
    Most shops that do the weld on and do a mild reshape say 2 to 3 mph over a stock skeg. I think you might see more If you get the gear case running straight and the prop hooked up better.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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    Last edited by Jones Racing #157; 09-08-2003 at 12:41 AM.


  8. #8
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    YOUR crankin my calcs @ 11% ASSUMING a 187 lower.

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