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Old 08-18-2005, 05:41 PM   #1
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Default Poor mans Dyno

I know, I should not be such a cheapskate and go out an by a real dyno, but......

If I take the motor I am testing and connect its shaft so it rotates another motor, when I power up the motor I am testing then I should be able to attach my mulit-meter(in 10 amp ammeter mode) to the tabs of the other motor and read amps output.

I can than compare the relative amps output of several motors or several different configurations of one motor. While kind of rough it will give me a benchmark to spot a weak motor or a motor with a potential problem.

I have read about using a resistor as a "shunt" when using a multimeter to measure amps, is this necessary in this case?

Is the above going to work or is it a waste of time?
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Old 08-18-2005, 05:45 PM   #2
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EXACTLY the principle behind the Bud's dyno I have. It uses a multimeter to give you reference numbers.

Basically, you've got to come up with a "baseline" motor -- one that you know works well on the track. All of your other motors will be compared to your baseline motor, and that will tell you whether it runs better or worse on the dyno. (On the track is another thing...) It can also help you figure out how to gear any given motor, as long as you can find that "gearing sweet spot" on your baseline motor.
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Old 08-18-2005, 06:59 PM   #3
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Although one "small" step better than a non-load motor checker device for comparing motor A to motor B......you'd still be missing several of the "most" important determining measurements that a true dyno can give about a motor.........a true dyno reading is more of a mixture of several important readings that are taken into consideration......not just Amps at one unadjustable load setting.......Even if you were to use a good dyno like the turbo 45 and just looked at the one reading your going for, it would tell you very little about the motor since your only getting one very small piece of the pie........For example:you can find two motors that are almost dead even in the amp draw readings (under a specific given load) but the RPM's, Torque, Watts, and effeciency can be off the chart different..........so, mabe fun to play around with,(like the motor checkers) but not really valuable for much else..........
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Old 08-18-2005, 07:50 PM   #4
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if you dont have the funds to buy a dyno, then let the track be your dyno follow the ten basic steps on rebuilding a motor and let your lap times be your guide.
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Old 08-18-2005, 08:53 PM   #5
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... and lets all remember that these "motor checkers" are not true dynamometers, so any information gained from them is speculative. The track is your best "dyno".
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