Current and Maximum Values for RPM, Torque, Power and Speed
These provide you with the "live" results coming from the dyno.  The values in the "Current" column will change rapidly as you run your dyno.  The "Maximum" values will remain at the maximum recorded value.  To reset the maximum values to zero, just click the "Reset Maxima" button. 

Picking Your Preferred Units
For each measure, you have a number of options for the units displayed.  You select the units you want to work with in the four framed group boxes labelled, "RPM", "Speed", "Power" and "Torque".  To change to your preferred units select the option button beside your preference.  For example, in the RPM group box you can select "Roller", "Wheel" or "Motor" and the current and maximum values for RPM will now be displayed in your chosen unit.

What to Plot?
Most of the window is taken up with the Data Plotting image (the large white one at top right).  As you select your preferred units in the framed group boxes, the axis in the Data Plot also change to match your chosen units.  You will also notice that each framed group box for "RPM", "Speed", "Power" and "Torque" have a "Plot" checkbox.  This checkbox works slightly differently for the "RPM" and "Speed" setting as compared to the "Power" and "Torque" settings.

For RPM and Speed, one of these items is checked at all times.  So if you check the "Plot" option for RPM, this option is unchecked for Speed.  Similarly if you uncheck the RPM option, the Speed option is automatically checked.

For Torque and Power it is a little different.  Because the "live" data for Torque and Power can be very noisy you may want to just turn both of these off.  So although you can only have one on at a time, you also have the option to uncheck both.

Note, RPM and Speed are plotted in green and Power and Torque are plotted in red.

Changing the Plot Axis Ranges
To change the RPM/Speed Y axis just enter the new maximum value in the "RPM Axis Max (Roller)" text box.  Please note that at the moment, the text box only accepts valid maximum Roller RPM values.  For example, if your Roller RPM Axis is set to 5000 RPM and you select the plot Speed checkbox, the Axis will correctly adjust the axis to MPH or KPH as represented by 5000 RPM on the rollers.  You cannot enter Y axis values in MPH or KPH units.  Also, if you are plotting wheel or motor RPM, you can still only set the Y axis maximum in Roller RPM units.  This will be made a little easier in later versions (like - way later).

To change the Power or Torque Y axis just enter the new maximum value in the available text box.  Note, if you have selected to plot Power, only the "Power Axis Max (Watts)" text box is available.  This is also the case is you have decided to plot the Torque values.  If you have decided not to plot either, then neither axis is available for adjustment.  For Power, you can only enter the Y axis values in Watts regardless of which Power unit you have decided to use.  Similarly for Torque, you can only enter the Y axis values in Newton meters (N.m).

To change the time axis, just enter the new time range in seconds.

Entering the Car, Dyno and Signal Parameters

Car Mass: Enter the car mass in grams.  This has no impact to any of your results.  However, you will notice at the bottom left of the window a line that says "Target Dyno Moment of Intertia = X.XXX kg.m^2".  This is the ideal moment of inertia for your dyno setup. If the combined masses and diameters of your rollers, end caps, axles and any "Extras" you add to your dyno produce an "Actual Dyno Moment of Inertia" value that matches this ideal number, then your Dyno will put your car under "real world" stresses as if it were driving on the street (ignoring air resistance effects).  If you read this before you build your dyno, this can help you select the right materials and dimensions to build an appropriate dyno for your car.

Frontal Area: Enter the frontal area of your car in millimeters squared.  To calculate this value multiply the max height of your car and max width of your car in mm.  This does not directly impact RPM, Torque, Power or speed data generated from the Dyno. However, if you perform a "Power Run" the software calculates what your power losses are due to air resistance and uses these to calculate a drag corrected top speed.

Drag Coefficient: Enter the drag coefficient for your car.  Values from 0.1 (really slick) to 1.0 (like a brick) are reasonable.  To get a better feel for what you might enter here check out the following guide. Again, this value only impacts the calculated losses due to air resistance during a "Power Run".


Gear Ratio: Enter your gear ratio here.  The gear ratio is the number motor revolutions it takes to turn the car wheel once. In almost all cases this value will be greater than 1.  The gear ratio does not directly impact the Power, Torque or Speed results, but it is used to calculate the Motor RPMs.

Wheel Diameter: Enter your car's wheel diameter in millimeters.  This does not impact Power, Torque or Speed results but it is used to calculate Wheel RPM.

The following parameters are all critical for accurate results:

Roller Diameter: Enter the diameter of your dyno rollers in millimeters.

Roller Wall Thickness: Enter the wall thickness of your dyno rollers in millimeters. It is assumed that the rollers are constructed using some sort of pipe or tube.  If you have solid, machined rollers then enter half the diameter for the wall thickness.

Roller Mass: Enter the mass of the driven rollers in grams.

Axle Diameter: Enter the axle diameter in millimeters.

Axle Mass: Enter the mass of the driven roller axles grams.

Endcap Mass: Enter the total endcap masses in grams. This will be the combined weight of the endcaps on the driven rollers.  If you are using solid rollers you can leave these as 0. Not that the endcap diameter and wall thickness are calculated based on the roller diameter and wall thickness and the axle diameter.

Extra Diameter, Wall Thickness and Mass: If you have built your dyno and have decided that you want to add more inertia to the system then you can add disks of various materials to the end of your driven axles. These are the "Extras".  Not only does this allow you to fine tune the dyno to meet your car's needs, being able to adjust the dyno inertia in this way will allow you to run different vehicles of different masses.

Note on the masses entered: The mass entered should cover the driven rollers. So, if you have a 4WD vehicle, enter the mass values of both front and rear rollers.  If you have a RWD vehicle, only enter masses associated with the rear roller.

Signals per RPM: Enter the number of magnets you have on the roller end.  This assumes you are using a single coil pickup.  Typically this value will be 1.

Signal Threshold: The input signal level at which the software should count a pulse.  Values can be from 0 to 255 however, there are some limits (+/- 3 units) as to how close you can set this towards the dead center of the range (otherwise you will be picking up noise).  The signal threshold can be above or below the center line.  To find out where it should be, connect your Dyno and spin the rollers by hand.  You should see the red trace pulse.  If it pulses cleanly on the high side, set the signal threshold above the mid line (131 - 255).  If it pulses cleanly on the low side, set the signal threshold below the mid line (0 - 125). Remember, you may need to adjust your mic volume in windows to get a clean signal.  Here is a screen capture of a real signal.  In this case the signal (red) is pretty clean both up and down.  The threshold (green) was set at 100, about 30 units below the mid line.




Logging Data and the Power Run
The "Log Raw Data" and "Power Run" buttons allow you to save the test data that you are generating using your Dyno.

Log Raw Data: Use to record results from your dyno for later import into different data analysis programs. Click on the "Log Raw Data" button and a Save File dialog will appear. Select the location where you want to place the file, give it a name and click "Save".  The "Log Raw Button" is now red and reads "Logging..." to let you know that the session is being recorded.  When you are done, click on the red "Logging..." button and your file will be saved.  The data files are space delimited text files.  The data stored in the file includes Time, RPM, Power, Torque and Speed.  The units will be your currently selected units.

Power Run: Use to analyze the max power output of your car based on acceleration from zero to max throttle with curve fitting of the raw data.  Clicking the "Power Run" button will lead to the same file saving process as described for "Log Raw Data".  NOTE: Due to a minor bug in the current version, you must set your time axis to a time which is a few second longer than you think it will take to complete the run.  When you return from the Save File dialog box, the button will be red and will read "Recording...".  The software now waits for you to max your car on the dyno.  For best results, simply floor it and hold the throttle at 100% until the RPM reach a plateau.  Then release the throttle and let the rollers stop.  The software waits for approximately 2 seconds for the rollers to remain stopped.  Then the button will return to being grey and read "Fitting curve...".  Please note, this can take 10 - 20 seconds to complete.  When the curve fitting process is finished, the button will read "Done" and you will see a plot of your raw RPM data with the fitted curve overlaid.  It should look something like this...


You can see in this example that my dyno was wandering around the bench a bit leading to a lot of noise in the plateau region.  When this plot is complete, you will notice that the "Show" group box is now available for you to select which plot you want to see.  The plot above is the "RPM vs Time" plot.  The next one is the "Power Curve" plot.

The plot shows Power, Torque and Drag curves for your run.  The Max values for RPM, Speed, Speed corrected for Drag, Power and Torque are printed at the top of the plot.  When you are done with your run, click the "Done" button and you will return to live dyno monitoring.  Note that along with the text file holding your raw data from your Power Run, there will also be an image file saved containing the Power Curve plot.

Speed Trap (no longer available)
The Speed Trap group box contains a single text box into which you can enter the length of your trap in feet.  This function is on all of the time.  It uses the time between pulses to calculate vehicle speed based on the distance traveled.  Obviously when you are running your Dyno, these numbers mean nothing. For more information on the Speed Trap concept see SpeedTrap