bowl shim?????????
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bowl shim?????????

  1. #1
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    Default bowl shim?????????

    anyone ever hear of a shim used to simulate or make any size impeller work like a smaller impeller

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  3. #2
    Senior Member blownsouthwind's Avatar
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    Default bowl shim

    I have!!!! It works great in my southwind tunnel. I Gained 5 to 6 mph @ the track.

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    im kinda curious as to this .. What exactly do you do ? Put a shim in where the gasket goes ?
    would this work on any bowl or just split bowls ?

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    i would love to try this ,im kinda hopin the racers would comment

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    show your tits topless000's Avatar
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    Default bowl shim

    Hey Mike this evolved from cutting down a customers impeller and the boat not liking it. Now i couldn't put the material back on and the guy had to buy a new one. So we created a pdf and had the first shim made last year. , i tested the idea at the track before offering it to you guys. The results were i gained 300 rpm and 6 MPH. Remember the same results can happen by cutting the impeller.(If the motor and boat like it) So results will vary. But if it does not help, you are out a shim and not an impeller. The shim also helps on repaired and milled bowls who have lost the clearance needed for the impeller. You Can double gasket it but gaskets that get thick seam to blow easier. Hell! you can buy a new bowl!
    Now if the shim helps the boat now consider impeller change or just run the shim like i do!!! Thanks Ron
    Last edited by topless000; 08-26-2010 at 07:21 AM.

  8. #6
    mo balls than $cents$ IMPATIENT 1's Avatar
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    Quote Originally Posted by topless000 View Post
    Hey Mike this evolved from cutting down a customers impeller and the boat not liking it. Now i couldn't put the material back on and the guy had to buy a new one. So we created a pdf and had the first shim made last year. , i tested the idea at the track before offering it to you guys. The results were i gained 300 rpm and 6 MPH. Remember the same results can happen by cutting the impeller.(If the motor and boat like it) So results will vary. But if it does not help, you are out a shim and not an impeller. The shim also helps on repaired and milled bowls who have lost the clearance needed for the impeller. You Can double gasket it but gaskets that get thick seam to blow easier. Hell! you can buy a new bowl!
    Now if the shim helps the boat now consider impeller change or just run the shim like i do!!! Thanks Ron
    how much$?

    Dare to be different, if it turns out great you can claim you planned it that way.

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    Quote Originally Posted by topless000 View Post
    Hey Mike this evolved from cutting down a customers impeller and the boat not liking it. Now i couldn't put the material back on and the guy had to buy a new one. So we created a pdf and had the first shim made last year. , i tested the idea at the track before offering it to you guys. The results were i gained 300 rpm and 6 MPH. Remember the same results can happen by cutting the impeller.(If the motor and boat like it) So results will vary. But if it does not help, you are out a shim and not an impeller. The shim also helps on repaired and milled bowls who have lost the clearance needed for the impeller. You Can double gasket it but gaskets that get thick seam to blow easier. Hell! you can buy a new bowl!
    Now if the shim helps the boat now consider impeller change or just run the shim like i do!!! Thanks Ron

    What kinda thickness we talking ? 1/16" ? 1/8" what thickness made your gains. ?
    Thanks

  10. #8
    Boat Nut sleekcrafter's Avatar
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    bottom feeder was testing bowl shims about 5-7 years back in his sprint boat. His results were interesting to say the least, I think he may have posted his results on the old HB forum.
    Upper Midwest Power Boat Association
    DRAG BOAT RACING UMPBA #926


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    Senior Member wajetboy's Avatar
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    i would like to know some more about this, i want to try it out.
    1978 Southwind Tunnel Dragster/1980 SWTD center steer

  12. #10
    Impeachment! 75 TX's Avatar
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    Quote Originally Posted by wajetboy View Post
    i would like to know some more about this, i want to try it out.
    X2. I'd like. to make my B+ think it's a B

  13. #11
    Boat Nut sleekcrafter's Avatar
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    found some info by bottom feeder:

    bottom feeder

    The gains I have seen from nozzel research are from a control stand point. With a given impeller spinning a given RPM with a known water density their is a ideal nozzle diameter. The adjustable nozzel has lead me to other areas that give a much higher return. An example would be the use of larger impellers (9.25 and 9.5) in conjuction with larger nozzels. I feel this has to do with the amount of movement put into the water.
    I ran tests over the summer on impeller cutting. As i seen it, the cutting down of the impeller to free up RPM was not the best way to gain RPM as it removed motion imparted on the water and inlarged what I call the reversion window for lack of a better term. The test I ran used the same same uncut 9.25 impeller, bowl that I detailed on a CNC mill and a selection of spacers and nozzel inserts. With out cutting the impeller I managed to alter the peak RPM that my motor would pull it to by 1600 RPM. Yes their was a large diferance in boat speed as one would expect. After running one set up I would note RPM and hull speed. I then tried to disprove my thinking by taking the same impeller and bowl in their stock locations and use the more known practice of turning the impeller. I did the same tests noting RPM and hull speed. As was epected I had a large spread in hull speed. The trend that showed was the hull speed was faster with the uncut impeller at the same peak RPM. What does all this mean? Not jack But I am am not cutting up a $900. part on a hunch anymore.







    still digging
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  14. #12
    Boat Nut sleekcrafter's Avatar
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    more by bottom feeder

    bottom feeder

    cyclone,
    As you have figured out it was done with spacers. They were placed between the sution housing and bowl. I would love to take credit but a freind of mine showed me the concept. We run into lock up issues much the same as what are seen in torq converters. Slighty differant vicositys and clearances but it will still approch lock up or "stall" with a nozzle that is to small to flow the required volume. If you are running a DA system and see a constant rise in bowl pressure and a decline in suction housing pressure what is going on?
    Upper Midwest Power Boat Association
    DRAG BOAT RACING UMPBA #926


  15. #13
    Boat Nut sleekcrafter's Avatar
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    more yet...

    bottom feeder

    The amout of spacer is quite small. The bowl spacers were .03 incriments ( to coarse) from .06 to .180. Moving the bowl out gained RPM. I would then go to the nozzel for the best speed
    Upper Midwest Power Boat Association
    DRAG BOAT RACING UMPBA #926


  16. #14
    show your tits topless000's Avatar
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    Default bowl shim

    Its nice to see that my testing has been verified!!! i never new someone else has tried shims. i have berk bowl shims in stock they are .100 thick. should be close to one cut size and they are 40.00$ plus shipping. Let me know if you need a bowl gasket as you will need one. Let me know!!!! WWW.TOPLESSRACING.Com or 623-326-1436 Thanks Ron

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