Current Density Altitude
Le Mans Master
Joined: Aug 2000
Posts: 5,294
Likes: 2
From: Suffolk, Long Island NY
Last edited by Face; Nov 10, 2006 at 01:28 PM.
Racer
Joined: Feb 2004
Posts: 455
Likes: 11
From: Roanoke VA
Use the calculator on this website to calculate the density altitude - http://www.srh.noaa.gov/elp/wxcalc/wxcalc.shtml
You can also use this website to get the weather information for any zipcode.
Calculate the dew point with the appropriate calculator to use for the da calculation.
You can also use this website to get the weather information for any zipcode.
Calculate the dew point with the appropriate calculator to use for the da calculation.
Thread Starter
Drifting
Joined: Feb 2000
Posts: 1,413
Likes: 10
From: Skillman NJ
I tried these calculators already and they don't seem to give the same numbers as the hand held devices used at the track. For example last Sat the DA was about -750 feet. If you use the calculator you get -1850 feet.
Racer
Joined: Feb 2004
Posts: 455
Likes: 11
From: Roanoke VA
Originally Posted by Dave-T
I tried these calculators already and they don't seem to give the same numbers as the hand held devices used at the track. For example last Sat the DA was about -750 feet. If you use the calculator you get -1850 feet.
You must use station barometric pressure when you enter the numbers into the internet calculator to get an actual da number. If you use the barometric pressure reading from the local weather service it is adjusted to 0' sea level so your actual elevation is not taken into account when making the calculation. This is not a problem if you are comparing sample to sample but it will make the da number different than your hand held device reads unless you are standing at sea level.
I use the weather station like I would use a dyno, don't rely on its actual number (hp or da) for one sampling but use them for comparative purposes.
In other words if you make a change in your motor or its tune what net effect is there on the dyno.
As the density altitude changes X numer of feet what net effect does that have on your et.
If you are bracket racing a very important thing is the ability to dial correctly according to changes in the atmosphere so I rely on accuracy from sampling to sampling.
