Performance Trends, Inc.

Producing Quality Computer Tools for Racers and Engine Builders since 1986

Weather Wiz

Weather Wiz v1.1 for Windows 98/Me/XP/2000/NT/Vista/Win 7

Computer Program to make Weather Calculations which affect Engine, Carburetor Fuel Metering and Vehicle Performance for Drag Racing, Circle Track Racing, Road Racing, Dyno Tuning, and Street Tuning

Our new Weather Wiz lets you easily make all those weather related calculations like Density Altitude, Relative Air Density, Dyno Correction Factor and more.  It lets you specify the inputs you want to use for entering barometric pressure, humidity and air temperature.  It also "talks" to our Weather Station for instant updates of critical data.

Unlike most programs, you don't have to use the same types of inputs for the comparison.  For example, your baseline condition may use a barometer instrument, and your comparison may use an altimeter.  Or your baseline condition may use wet and dry bulb temperature for humidity, but a dew point reading for your comparison conditions.

It also lets you specify the air temperature at the engine (which is the critical temperature) different than where the humidity was measured.  For example, your relative humidity instrument (or wet and dry bulb instrument) may be in your trailer or dyno control room.  However, the air going to the engine may be considerably warmer.  This definitely has an effect on engine performance and carb and mechanical fuel injection jetting.

Options for Reading Weather Station



  • Can read our DataMite "Stand Alone" Weather Station (see picture above of screen options and picture below for actual hardware).  It measure Barometric Pressure, Air Temperature, and Humidity and has a recirculating fan for fast response to weather changes.  It needs only a USB cable for communications and power, and Weather Wiz software to read it.  4.25 x 3.00 x 1.38 inches (108 x 76 x 35 mm)
  • Enter Barometric Pressure in:
    • Measured "True" or Actual Pressure like with a barometer at the track or shop
    • Corrected Pressure (like from a TV or radio weather report) and elevation
    • Altimeter from an aviation altimeter corrected to 29.92 and 60 deg F
  • Enter Humidity in:
    • Dew point
    • Relative Humidity and the temperature where the relative humidity was measured
    • Wet and dry bulb temperatures
    • Water vapor pressure in inches of mercury
    • Grains of moisture per pound of dry air
  • Show calculated outputs of:
    • Dew point
    • Relative Humidity
    • Water vapor pressure in inches of mercury
    • Grains of moisture per pound of dry air
    • "True" or Actual Barometric Pressure
    • Corrected Barometric Pressure like from a TV or radio weather report (corrected for elevation)
    • Density Altitude (typical calculation, not correcting for humidity)
    • Dry Density Altitude (correcting for humidity)
    • Relative Air Density 
      • Standard Definition
      • Standard Definition, but correcting for humidity
      • Correcting for Humidity AND correcting for Temperature in a method more accurately for engine performance predictions
  • Save, save as (to a new name), delete, and open your sets of conditions to either the Baseline Side or Comparison Side of the screen.
  • Copy conditions from one side to the other, or swap conditions with one click buttons.
  • Print your results.
  • Lets you do side by side comparison of all jets for your carb(s), 2 barrel, 4 barrel, three 2 barrels, two 4 barrels, etc.
  • Lets you correct for the size power valve you are running, or perhaps there is no power valve restrictor.
  • See how much richer or leaner your engine will run with out rejetting, or see what the Weather Wiz would recommend for rejetting.
  • Lets you copy weather readings from our DataMite data logger software for doing additional weather analysis, like jet recommendations.
  • Predict changes in A/F ratio for mechanical fuel injection for:
    • Weather changes
    • Fuel Injector Nozzle size changes
    • Pill size changes
  • Program suggests new pill size for mechanical fuel injection to keep A/F constant for changing weather and injector nozzle sizes.
  • Program predicts change in fuel injector pump pressure for changes in pill or nozzle sizes.

Weather-Wiz-Mechanical-Fuel-Injection.gif (31980 bytes)  Click image to show Mechanical Fuel Injection showing A/F change when not changing nozzles or pill. 

Weather-Wiz-Mechanical-Fuel-Injection-w-changes.gif (33117 bytes)  Click image to show Mechanical Fuel Injection with almost no A/F change after changing nozzles and pill.  You could have selected to just change pill size, which is what most tuners would do.  Also, if you entered the exact pill size suggested, the A/F change would have been 0%, no change in A/F.


DataMite "Stand Alone" Weather Station  

  Part Number WW11-WS (comes with FREE Weather Wiz software)



What you need:

Computer with Windows 98/Me/XP/2000/ NT, Vista, Windows 7 and USB port.


More Information, Download Demo:

to go to our Demo Downloading page to download a FREE Weather Wiz Demo.

for Weather Station prices.


To Order the Software Only:

Weather Wiz: Our DOWNLOAD ONLY option for the Software Only. If you only want the unlocking code and DO NOT want a CD shipped, click on Add to Cart below. You will not be charged shipping.


Weather Wiz: If you want a CD shipped to you for the Software Only, click on Add to Cart below. There will be shipping charges added to your order. You can still download the demo and get your unlock code sooner with this option.

$49.95 plus shipping