Frequently Asked Questions about the Facts Machine DOS Dyno Program

Click on a question in the list below to jump to the answer.

  • Where do I send my Fantom Dyno for authorized repair?
    Wizard Electronics has always been the service center for the Fantom Dyno. Al may be reached at (616) 621-4315 or via e-mail at to make arrangements to have your dyno serviced.
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  • How do I set up the DOS Dyno Program to calculate gear ratios and/or rollout?
    The dyno tells you how fast the car has to go to do the number of laps you tell it you're going to run in the 'Oval Gearing Screen'. That's the 'MPH Needed'. The dyno also looks at the motor characteristics and information you provide to determine the average speed the car will travel for the entire race period. That's the 'Ave. MPH'. If the Ave MPH is the same as or faster than the MPH needed then you will likely make time. If the Ave. MPH is less then you will probably dump.

    'Track Length' - Your dyno should have the distance your car "sees" per lap. The actual track length as measured, however... is only a starting place for your calculations.

    Basically, you should do this:

    Test a motor you want to run and save the results under the new track name. Put the motor in the car and run it with someone counting your laps. When you're done bring up the motor test you just did and get to the oval gearing screen. Enter all the information about the run you just made with that motor. Does the dyno match the pinion and spur you used? If so, touch the F7 key to make sure. If they still match then you're the first person to be so lucky. If they don't agree on the gear ratio then first make sure the dyno is using the spur you did and then start changing the Track Length until the dyno is telling you the same two gears that you had in the car.
    It's okay to fudge the laps and/or the run time if you feel the test run was not clean. Don't try to tell the dyno you ran the track record unless you have. Even if you have the opportunity to dyno the record holding motor it is not much use to you unless you ran the motor in your car and then tell the dyno what you did with it in your car.
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  • What about changing the RPM Factor?
    If you are using the RPM Factor to adjust your gear ratio/rollout you are NOT getting accurate results. When you manually change the RPM Factor you are forcing the motor characteristics to change. The dyno is designed to find the best setting based on what you want to do. Part of what you want to do is included in the track length value. By changing the track length to what the car sees each motor will then know what it is expected to do.
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  • I've noticed guys tuning there stock motors at 18 and 22 amps, do these numbers have some meaning?
    Modified motors should be tuned at the 26 amp mark. Most battery packs are just about dumped in 4 minutes at this rate. If your packs are almost dumped when racing stock, and a lot of that depends upon the track, setup and so on, then I would lean more toward the 26 amp mark. If you aren't able to "almost" dump your packs then I would agree; tune your stock motors at a lower amp mark. Tuning at a lower amp mark will cause the motor to have more pull on the "top end", assuming "tuning" means "for maximum torque", so now the question becomes; is it a "tight" track that needs the "grunt" off the corners or a "flowing" track where you can keep the rpm's up through the turns.

    My rule of thumb has always been to look at my motors and find the one that "spins up" in the least amount of time. Look at that reading carefully though because you may choose a motor that has a spin up time of 2.0 seconds to 15,000 rpm over a motor that shows a spin up time of 2.2 seconds to 18,500 rpm. In a case such as this I look at both motors in the "Time Base Data" screen to see which motor got to say, 14,000 rpm first. In other words, the 2.2 second motor revved to a much higher rpm level and probably past the other motor's 15,000 rpm point in under 2 seconds.
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This page and it's contents are Copyright © 1997 ~ 2000 by Dave Clary, DBA; decCo SoftWare.