DIY dyno build

Discussion in 'Old's Cool' started by adrenal, Aug 23, 2013.

  1. pommie john

    pommie john Long timer

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    I hope it's still in balance after the grooves have been machined :evil
    #41
  2. adrenal

    adrenal skrunkwerks.com

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    So do I!!!
    Solid carbide tool and very shallow cut so there shouldn't have been too much tool wear. Also that machine is pretty accurate. We'll see what happens during the first pull :eek1
    #42
  3. drhach

    drhach gorillamanufacturing.com

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    Thanks. I know that cooling is the trick with brake dynos and that Hysteresis is a big issue. I guess from where I'm sitting, it doesn't seem to much harder to solve that the measures that you are taking for the inertia dyno. However, if the inertia dyno suits your needs then that's good enough. I don't have the means to build either one. So there ya go. Great work by the way.





    #43
  4. Garbln

    Garbln Been here awhile

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    at one time I worked for a company that made small to medium size engines, 1 cyl to 6 cyl. We used solid machined flywheels and we always balanced them. They always needed balancing. Solid steel isn't always the same density all over I guess.
    #44
  5. _cy_

    _cy_ Long timer

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    static balancing the lump o steel should be minimal fuss. simply mount in two low friction bearings. process should be substantially same as video below.

    this has got to be the clearest how to balance a wheel video anywhere.

    <iframe src="http://www.youtube.com/embed/bBzviKTPMrg?feature=player_detailpage" allowfullscreen="" frameborder="0" height="360" width="640"></iframe>
    #45
  6. adrenal

    adrenal skrunkwerks.com

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    Thanks for the heads-up CY. Great VID that!
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  7. _cy_

    _cy_ Long timer

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    can't wait to see pic's of this beast in action!
    #47
  8. bpeckm

    bpeckm Grin!

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    ....is it time to ask if you would ship it to Rhode Island so that I can test my bike......








    :*sip*


    :eek1 ... freekin' amazingly awesome!!
    #48
  9. pommie john

    pommie john Long timer

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    He'll be too busy bringing it around Australia.
    #49
  10. adrenal

    adrenal skrunkwerks.com

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    It's only got one wheel! You guys have the two wheeled machines. Much easier for you to come to me...:ricky
    #50
  11. adrenal

    adrenal skrunkwerks.com

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    pretty pumped about getting it together:

    [​IMG]

    [​IMG]

    [​IMG]
    #51
  12. _cy_

    _cy_ Long timer

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    OOOOoooohhhh ... NICE!!!!
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  13. cam14

    cam14 Been here awhile

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    The level of quality in your work and execution are very impressive. I have a question based upon my experiences with dyno tuning my race car. Under load, I adjust fuel pressure for better air/fuel ratio (I have a wide band) and I adjust ignition timing; per the rules, not allowed to adjust much else. I can tell if the changes I made were good or not based on the torque and horse power curves. So back to the question, does your inertia dyno have a way to measure TQ and HP? If yes, then how? If no, then how will you use your dyno?
    TIA<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:eek:ffice:eek:ffice" /><o:p></o:p>
    #53
  14. pommie john

    pommie john Long timer

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    Inertial dynos measure the rate of change of speed of the drum which is proportional to the torque at the rear wheel. If you measure at short enough intervals and read the RPM of the motor at the same time you have enough information to measure torque and from torque and RPM, you ( or your computer ) can calculate horsepower.
    #54
  15. adrenal

    adrenal skrunkwerks.com

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    Thanks for your kind words.

    The inertia dyno produces torque V HP V AFR curves just like all dyno's. I think you'll find that many commercial dynos out their are the inertia type simply because they are cheaper. Some do both.

    So you must be using a brake or absorption style dyno if you are twiddling while the bike/car is being held at steady state at a particular RPM. As you describe, that's the big advantage of these types of dyno.

    With an inertia dyno, you have to do a run (typically 6-12 seconds), check HP TQ, AFR etc along the curves for a series of RPM's, twiddle, then do another run to check the result, then repeat

    The advantage of inertia dyno aside from cost is that it more accurately replicates the conditions that the machine will see on the road which is why they are also called rolling road dynos. Particularly if the rotating mass is well matched to the machine which is what I've tried to do - we'll see what happens at the first pull! Inertia dynos also stress the machine less since run time is generally shorter.

    Hope this explains things. :D
    #55
  16. ttpete

    ttpete Rectum Non Bustibus

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    The biggest problem with an inertia dyno is that you can't do steady states and really tailor make an effective throttle opening vs. rpm fuel map. It's fine for a WOT max acceleration study, but there's a lot in between that needs to be addressed.
    #56
  17. Beemerboff

    Beemerboff Long timer

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    If he had a Monolever a clever/knowledgeable man could link a strain gauge on the bottom link to an accurate rev counter, and on to a bit of electrickery, and get a reading , on the move, which would combine both inertia and brake dynos, that is instant HP at any given revs, and also the rate of change.
    #57
  18. weldingrod

    weldingrod Adventurer

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    You lost me there Dude...but it sounds very impressive. All in all, anything which can help you measure modifications, be it benefit or detriment, helps with the learning curve....and if you get an instantanious read out, it all moves the process along faster.
    #58
  19. ttpete

    ttpete Rectum Non Bustibus

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    You're still limited to transient data. It's not possible to run steady states, and that's how most development work is done. You could couple that drum to a water brake and have a more versatile rig.
    #59
  20. Beemerboff

    Beemerboff Long timer

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    You could just put it on the centrestand and run it against the back brake, for a steady speed measurement.

    And a pendant might point out that as torque can only be measured at a steady speed , UNLESS YOU MEASURE AT STEADY SPEED YOU AINT ACTUALLY MEASURING HORSEPOWER.

    They are still a useful tuning/ comparative tool, which is what they are intended to be , but a 62 BRAKE HP Vincent will outperform most 120 INERTIA HP bikes.
    #60