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    • CommentAuthorkamran
    • CommentTimeDec 17th 2009
     
    Hello all,
    I'm looking for a plan as how to make a water pump for my 2 cylinder 4 cycle engine.

    also I might want to consider a electric water pump. Any idea where I can get a small electric water pump?

    Thanks
    kam
  1.  
    Kamran There has been two or three show up in Modle Engine Builder Mag. one i rember seeing would be a good pick. By the way it has been a while any pictures of you new engine?
  2.  
    Depending on cooling demand, if you are looking for volume to cool the engine, I have used with great success electric fuel pumps for 12 volts. I use this under the stand for the engine and they are hidden away so if the are ugly, no one knows.
    If you are looking to make one and then attach it to an electric motor, you can build one with impeller and volute design, the V8 challenger has one quite nice and easy to machine, or you can build one with two gears like and oil pump, however this design does lack the volume part and do not cool down as efficiently as an impeller type pump.
    Now you can also use a wiper washer pump from an old (1980 - 1990) Volkswagen, like a vanagon, jetta and use some flexible hose, they run at 12 volts and can be hidden under the box/stand of the engine, they tend to be more noisy but they are small and cheaper, at around 15.00 us.
    • CommentAuthorkamran
    • CommentTimeDec 18th 2009
     
    Yea I like the idea of wiper washer pump. Maybe I can replace the motor to lower voltage (3-6 volts).

    Bob, I just finished the fuel tank and the distributor. Once the radiator is built, I'm done and will send more pictures. Then you need to help me to get it to run :)
  3.  
    MEB Issue 10 (Jan-Feb 07) describes a gear type water pump built for the Upshur Marine Engine. A pair of 15 tooth gears, 0.120" thick, are built into two rectangular blocks.

    Garry
    • CommentAuthordavid
    • CommentTimeDec 18th 2009
     
    Gear pups are great. just a driven gear and an idler. The fluid goes in where the gears mesh, they are placed in a body that conforms to the gears +0.001. The fluid is carried around the outside of the gears between the teeth, then they mesh again the fluid is pumped out another port where they mesh. Pressure is determined by the gaps to the body and the flow restrictions. A great little pump you can build and fits in the model.
    • CommentAuthorgbritnell
    • CommentTimeDec 18th 2009
     
    Kamran, what size are you talking about. I made a centrifugal type for my Holt engine and it works very well. I could send you a PDF file if you like. It has all the major dimensions on it.
    gbritnell
    • CommentAuthorkamran
    • CommentTimeDec 18th 2009 edited
     
    From what David described, it's easy to make a Gear pups.

    George,
    my engine is is a 2 cylinder 1" bore x 1" stroke. If you don't mind, I would like to see the plan you have,

    kn592@yahoo.com

    Thanks
    • CommentAuthorgbritnell
    • CommentTimeDec 18th 2009
     
    Kamran, the information is on it's way. I sent a PDF file with dimensions and I sent some pictures so you could see what it looks like. I hope this helps.
    George
    • CommentAuthorkamran
    • CommentTimeDec 19th 2009 edited
     
    Thanks you George for the plan and the pictures.
    By the way that is a very nice looking engine you have. Do you have a video of it running?

    ->link<-
    • CommentAuthorgbritnell
    • CommentTimeDec 19th 2009
     
    Hi Kamran, yes I have a video on Youtube. I don't know whether the link will work on here or not but here it is. If not just go to Youtube and search for Holt.
    George
    • CommentAuthordavid
    • CommentTimeDec 19th 2009
     
    Kam, use 2 gear like you would use for timing, ½ or 5/8 diameter about 1/8 thick. Thicker and larger teeth pump more. Drive it from the main shaft. The size sounds right for a small engine and it scales up or down. They are often used for oil pumps and I believe Bob Shores used them for coolant.
    Make a test pump from some scraps. The gears don’t actually need to be the same diameters. Limit clearances have a good bearing for both shafts.
    You probably don’t need much flow so these small parts will work.
    We use gear pumps at work, well $4000 versions, stainless or tool steel with 0.0001 clearances and they make pressures in the 3000+ PSI range.
    • CommentAuthorkamran
    • CommentTimeDec 19th 2009
     
    Hello David,
    Yes I'm also considering the external gear pump and also centrifugal type mentioned by George. I have a very limited space to work with so I have to see which is best fit for my engine.
    I might even have to go with what wiper washer pump mentioned by Jaime
    However so far I have got some great information in this discussion.
    • CommentAuthorkamran
    • CommentTimeDec 21st 2009 edited
     
    After going back and forth and consider all options, I decided to go to with the external gear pump.

    The gears I'm planning to use are 2 spur gears

    14.5 degree pressure angle
    24 pitch, 12 teeth, .5" PD, .56" OD

    Crankshaft pulley: 1" diameter
    Pump pulley: .5" diameter

    based on this formula


    G=(N*W*C*(D-C))/73.48

    G=pump flow(gpm)
    N=speed (rpm)
    W=gear face width (inches)
    C=center distance between gears (inches)
    D=gear OD (inches).


    at 1000 PRM It can pump ~ 17 OZ of water / min
    at 2000 PRM It can pump 32 OZ of water / min

    I know there is more to it by just using the above formula, but that should be sufficient enough for what I'm planning to do.

    The engine is a 2 cylinder 1 X 1 bore stroke.

    Any comments?
    • CommentAuthordavid
    • CommentTimeDec 21st 2009
     
    Gear pumps with no leakage are perfect pumps. As the clearance increases wall to gear tooth or gear face to cavity face there is leakage called slip. If the calculations have an ideal pump at a flow a sloppy pump (.001 TIR) should be able to do 25%. So it sounds perfect for a model.
    When I use these pumps I am often looking for very low flows, under 100 RPM and they work text book. One common use is with water at 1800RPM to increase the pressure to mix it with CO2 to make carbonated water. Carbonators are all brass and bronze so it should be no problem.
  4.  
    Kamran;
    This link may be of interest to you,
    ->link<-

    Garry
    • CommentAuthordavid
    • CommentTimeDec 30th 2009
     
    Beautiful gear pump example.
    • CommentAuthorkamran
    • CommentTimeDec 30th 2009
     
    Very impressive work. I wish I had the link sooner
    Today I completed the water pump. I'm planning to test it tomorrow to see how well it works.
    Will send in some pictures soon.
  5.  
    Kamran;
    Here's another to spark your thinking!
    ->link<-

    Garry
    • CommentAuthorkamran
    • CommentTimeDec 31st 2009
     
    tested the pump today and is not working. must a leak somewhere?
    Here are pictures of the pump
    ->link<-

    ->link<-
  6.  
    Take a look at the inlet and outlet port configuration in the following link

    ->link<-
    • CommentAuthorgbritnell
    • CommentTimeDec 31st 2009
     
    It won't work the way you have it built. The water has to be picked up at one side of the gear mesh and is carried in the space between the teeth. As the teeth mesh back together they squeeze the water out.
    gbritnell
  7.  
    move your ports 90 degrees. In your photo the ports are at the left and right. Move the ports to the top and bottom. If you draw a line thru the ports the line will go thru the gear where they mesh.
    • CommentAuthorkamran
    • CommentTimeDec 31st 2009
     
    Oops, that was kind embarrassing mistake :)
    Thanks for the tip. I think I still have enough room to make the modifications