Dyno and/or Track Evaluation and Repeatability
 

Because the weather changes the power an engine produces, the most important tool for performance evaluation is a weather station. Knowing the weather affect on performance, and correcting the observed readings to Standard Day Conditions, makes it easy to see differences in parts, tuning, or driving techniques. Weather stations don't all read the same. It's not necessary to know the exact weather readings of air temperature, relative humidity, and barometric pressure. It's more important to know the DIFFERENCE in weather from one condition to another. ALWAYS USE THE SAME WEATHER STATION. Own one and take it with you to a dyno session or a track event. This is the weather station I use. It will correct dyno and drag numbers to Standard Day Conditions using either the SAE method or the STD method. The SAE method is more accurate but usually ends up with lower values.

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