20 — H
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Calculating ADI and Density Altitude
Using Absolute Pressure
For this example, you are at the Los Angeles County Fairplex
Auto Club Raceway in Pomona, Calif. The track’s elevation is
about 1,025 feet above sea-level. The current local measured
weather conditions are 63.2° F, absolute pressure of 28.83 in Hg,
and 58% relative humidity at 9 a.m. Note that when you have the
current, measured absolute pressure, you do not need to enter
the track elevation.
Calculate the Air Density Index (ADI) and density altitude for this
example.
KEYSTROKES DISPLAY
0.
1. Enter current local measured weather conditions:
TEMP S 63.2 °F
(Absolute Pressure)
P-ABS S 28.83 INHG
(Moisture/Relative Humidity)
RH% S 58. %
2. Calculate ADI and density altitude:
ELEV S 0.
ADI 94.641 %
D-ALT 1873.414 F
Recall that ADI is a ratio, expressed as a percentage, of the
current air’s density to that of MSA. At the Auto Club Raceway
under the aforementioned weather conditions, the air’s density is
about 94.6% of that of MSA. Notice that the current air conditions
at 1,025 feet above sea-level are theoretically the air conditions at
an elevation of about 1,873 feet above sea-level.
In the next example, you are at the Firebird International Raceway,
just outside of Phoenix, Ariz. The track’s elevation is about
1,082 feet above sea-level. The current local measured weather
Summary of Contents for Hot Rod Calc 8703
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