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  • Home Made Dyno

    I have been looking at building a dyno for quite some time but it has been a challenge to get permission from the missus, finally after almost 15 years of subtle badgering she has stopped saying no.

    Starting from 1982 I would have spent many many thousands of dollars getting my cars dyno tuned at Scotts Dyno and Precision Auto Conversions in Newcastle, I ended up quite the Dyno Fly as I went to Newcastle's Tighes Hill Tech every Monday for Electrical Engineering for 4 years and was able to get to Scotts Dyno twice a day during breaks for around 2 - 3 hours to just stand and watch what they were doing, after 4 years I regretted being an eleco and wanted to be a mechanic instead .

    The last car I had dynoed at Scotts Dyno by Gary was my close to stock VL Turbo that made a modest 198HP at the rear wheels, was a nice smooth ride.

    After Pitstop motorcycles the motorcycle mechanic I have been using for the past 40 years picked up an inertia dyno around 20 years ago I wanted one real bad, spent so much time there I thought that I had squatters rights and was gutted when he sold it to move on to his much bigger and better Dyno Dynamics unit, so I started to quietly collect what I needed to make my own inertia dyno.

    Have looked at a few different designs including a flywheel dyno for engines and a chassis dyno using a traditional roller as well as a design that uses a large old electric motor:

    - Flywheel Dyno:

    Flywheel Inertia Dyno.jpg



    - Chassis Roller Inertia Dyno:

    Chassis Dyno Roller.jpg



    - Chassis Electric Motor Dyno: https://www.youtube.com/watch?v=XUX_YWsECWs

    Rotors.jpg


    Being an eleco I liked the idea of using an old electric motor but the main issue with AC motor rotor use would be calculating the inertia of a rotor of an unknown density. This didn't worry me too much as I am not really interested in getting an exact HP reading that is comparable to other dynos as I just want to be able to work out power improvement percentages when testing engine kits and exhausts to find out how much of an improvement from where we started. I was looking at other options as I was having trouble finding a decent suitable large burnt out motor till I dropped off some parts to a customer this week and found a yard full of old electric motors near Newcastle only 30 minutes from home.

    About 10 years ago I had some quotes from a few different machine shops to machine a round billet into a one piece dyno chassis roller, was told between $1000 - $2000 at the time completed depending on how I wanted it done, got a quote last week from a local steel supplier for a 400mm Diameter x 800mm Long round steel billet and was told $2500.00 just for the metal, could have cried .

    I have a few mates that run machine shops so i have to pay them a visit to see what it will cost to machine up a one piece roller these days.

    This is a drawing of the design that I will use if the electric motor method does not work out, just have to shrink it a little as I only really need 2HP to 40HP capacity with add on 50mm thick flywheels if I needed anymore. This design used the least metal as I can get a 400mm Diameter x 300 Long chunk of metal and get a shaft turned up to suit, if you turn a 400 x 800 lump down to a 300 wide drum with a 250 x 80 axle ether end quite a bit of your investment ends up on the floor as shavings:


    Dyno_drum_dwg.jpg


    Here is how it all comes together:

    Dyno_drum_3D.jpg


    dyno_shaft3.jpg


    dyno_grooves4.jpg


    dyno_boltup2.jpg


    dyno_boltup3-940x705.jpg


    I have 2 x UC Torana front discs and calipers with low dust pads so I can use it to stop and/or load up the dyno if needed for short runs.

    Next step is to go to the electric motor graveyard and see if I can find a motor with a healthy rust and corrosion free rotor. intact end plates and a decent size shaft poking out both ends.

    Will get up some more pics.

    Cheers

    Jaimie
    Classic Honda 50's Australia - Visit our online store at - www.classichonda50saustralia.com.au

    PERFORMANCE, REPRODUCTION AND OEM PARTS TO SUIT OLD AND NEW HONDA AND OTHER 4 STROKE MINIBIKES AND MOTORBIKES INCLUDING KAWASAKI, YAMAHA AND SUZUKI.

    Parts to Suit: Honda Z50A, Z50J1, Z50JZ, Z50R, Z50JDM, Z50M, QA50, QR50, MR50, XR50, CRF50, ATC70, CT70, CZ100, MSX125 (Grom), ST70, SL70, XL70, TRX70, XR75, XR80, TRX90, Kawasaki KLX110 and Z125 models to name a few.

  • #2
    Jamie,

    I've had the odd thought about knocking one of these babies up as well, did you consider fabricating/assembling the drum unit out of smaller components instead of one piece? Would have been cheaper, care would have been needed to ensure the design/fabrication/assembly in terms stress/fatigue, and if there's lack of inertia then a filler material could have been used....but that's all half the fun to work out! For simplicity though, its hard to go past a solid blank machined appropriately, there's much less risk involved.

    If you have trouble calculating inertia of a rotor, for what ever reason, you can just measure if a bunch of different ways, easiest would be to time it spinning axially when hanging from a line, similar to a pendulum on an old school clock.

    Jake

    Comment


    • #3
      It's actually quite easy to work out.

      We'll call the diameter 'A' and the rotational speed 'C' add this to the width 'D' plus again rotational speed 'C' again, then multiply by four times the mass.

      So the formula is ACDC4XMASS
      Once I thought I was wrong, I was mistaken

      Comment


      • #4
        Here's a design.

        https://www.youtube.com/watch?v=fg3HoWSFjiU
        Once I thought I was wrong, I was mistaken

        Comment


        • #5
          Im at the front door jamie ,,!!!
          its engine oil madge ,,,
          Your soaking in it ,,!!

          Comment


          • #6
            You drinking peter ,,?!?!
            its engine oil madge ,,,
            Your soaking in it ,,!!

            Comment


            • #7
              I have seen some scary shit on the dyno personally with nuts and bolts hitting the roller and shooting off like a bullet through walls, dyno eddy current assembly throw itself to pieces, saw a video years ago of a home made cement filled cylinder dyno roller throw apart and broke both legs of the operator and a drive chain that come off and stripped all of the skin off one side of a dyno assistants face.

              When your cock and balls are sitting direct above a rotating lump of metal I want to make sure that there is no way it will come apart and give me a sex change

              I want to make my unit strong enough to last forever, 40 - 50HP is not a lot of load anyway but at full revs the lump of metal gets along with a shitload of stored energy, here is a run on the big version of the dyno in the tech drawing:

              http://skrunkwerks.com/skrunk/diy-dyno-build/


              Here is a good simple design that you can use from the people that will be supplying me with the electrical hardware and software:

              http://dtec.net.au/Inertia%20Dyno%20Design%20Guide.htm


              To calibrate the dyno to a known standard I have 5 bikes to take to Niges dyno and should have a 2HP, 8HP, 12HP, 15HP and 18HP range of bikes to compare to and see if the software can be adjusted to give a similar reading.


              Cheers

              Jaimie
              Classic Honda 50's Australia - Visit our online store at - www.classichonda50saustralia.com.au

              PERFORMANCE, REPRODUCTION AND OEM PARTS TO SUIT OLD AND NEW HONDA AND OTHER 4 STROKE MINIBIKES AND MOTORBIKES INCLUDING KAWASAKI, YAMAHA AND SUZUKI.

              Parts to Suit: Honda Z50A, Z50J1, Z50JZ, Z50R, Z50JDM, Z50M, QA50, QR50, MR50, XR50, CRF50, ATC70, CT70, CZ100, MSX125 (Grom), ST70, SL70, XL70, TRX70, XR75, XR80, TRX90, Kawasaki KLX110 and Z125 models to name a few.

              Comment


              • #8
                You could hook the dyno up to a generator and wire it to your house......free electricity. That'll get Brownie points with the Mrs.
                Once I thought I was wrong, I was mistaken

                Comment


                • #9
                  Being a licenced eleco I already have plans to add an electrical type of brake by running a bank of three 12v alternators per side to allow me to add a staged load, for those of us that had a dynamo to run the lights on their old pushbikes will know how much load can be produced by such a small unit.

                  I have seen a home made dyno using a large DC generator as a brake where the power generated was dissipated in a large commercial 2 element hot water heater, I will be installing a 2KW solar system on my shed roof with a few 12v/600AH back-up batteries that I hope to plug the dyno into, may as well turn some of the cash spent on fuel into electricity.

                  Cheers

                  Jaimie
                  Classic Honda 50's Australia - Visit our online store at - www.classichonda50saustralia.com.au

                  PERFORMANCE, REPRODUCTION AND OEM PARTS TO SUIT OLD AND NEW HONDA AND OTHER 4 STROKE MINIBIKES AND MOTORBIKES INCLUDING KAWASAKI, YAMAHA AND SUZUKI.

                  Parts to Suit: Honda Z50A, Z50J1, Z50JZ, Z50R, Z50JDM, Z50M, QA50, QR50, MR50, XR50, CRF50, ATC70, CT70, CZ100, MSX125 (Grom), ST70, SL70, XL70, TRX70, XR75, XR80, TRX90, Kawasaki KLX110 and Z125 models to name a few.

                  Comment


                  • #10
                    Extra handy when there is a blackout. You can run the house electrical needs off Monkey power ......

                    Comment

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