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slower it will go. More specifically, engine performance is
impacted by the ambient air’s density.
MSA includes three parameters: absolute pressure (29.92
in Hg), temperature (60° F), and relative humidity (0% RH,
or “dry air”).
HPc*
The Horsepower Correction Factor is calculated and
implemented within HP, ET, and MPH estimations on the
Hot Rod Calc. The current local weather conditions and/or
elevation entered into the calculator are used to calculate
HPc.
As a guideline, the closer the HPc is to 1.0, the faster
the vehicle will run (more horsepower is produced).
Conversely, the higher the HPc, the slower it will run (less
horsepower is produced).
* Patrick Hale, “Motorsports Standard Atmosphere and Weather
Correction Methods”, Arizona: DRPro, 2008.
Density Altitude
Density Altitude is an MSA elevation that has the same air
density as the current, local measured weather conditions.
Meaning, your physical elevation might be 4,000 feet
above sea level, but the current air conditions are like a
“theoretical” perfect day at 5,000 feet. Density Altitude is
simply a corrected elevation, and is calculated using the
current, local measured weather conditions entered into
the calculator.
Air Density Index
Air Density Index, ADI, is a ratio (expressed as a
percentage) of the current air’s density to that of MSA.
The ADI at MSA is 100%. ADI is calculated using the
Summary of Contents for Hot Rod Calc 8703
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