1/4 mile DA
Le Mans Master
Joined: Aug 2008
Posts: 5,578
Likes: 61
From: Austin TX
Density Altitude. It's how dense the air is, the more dense the more power an engine will make. You can do a google search for "density altitude calculator". Values to enter are barometric pressure, temperature, relative humidity, and field elevation. The result will give you a value in feet relative to sea level standard (baro pressure of 29.92 and 59*F, zero elevation). A negative value means the air is so dense you are below sea level. Some areas, particularly the northeast, regularly see DA in the negative thousand's of feet. Other areas see very high DA.
Thread Starter
Racer
Joined: Nov 2007
Posts: 327
Likes: 0
Density Altitude. It's how dense the air is, the more dense the more power an engine will make. You can do a google search for "density altitude calculator". Values to enter are barometric pressure, temperature, relative humidity, and field elevation. The result will give you a value in feet relative to sea level standard (baro pressure of 29.92 and 59*F, zero elevation). A negative value means the air is so dense you are below sea level. Some areas, particularly the northeast, regularly see DA in the negative thousand's of feet. Other areas see very high DA.
http://www.dragtimes.com/da-density-...calculator.php
Le Mans Master
Joined: Feb 2006
Posts: 5,762
Likes: 4
From: Chandler Arizona
I know how you feel, Phoenix is about the same as Oklahoma City. But at least Houston is less than 7 hours due south of you. Take a trip in the winter down to Houston and you will definitely get your PB.
Safety Car
Joined: Aug 2006
Posts: 4,206
Likes: 6
From: Makena, Maui & NM
Yes. You can figure about .10 gained for every 700 to 800 DA change. So if you did a 12.10 at +1,000 DA and went somewhere where the DA was -1,000, the 2,000 DA swing (2000-700=3) would give you an approximate 11.80, all things remaining the same other than changes in the altitude/weather.
Le Mans Master
Joined: Mar 2002
Posts: 6,885
Likes: 2
From: Corpus Christi TX
Found this site on Google. Thanks for the response.
http://www.dragtimes.com/da-density-...calculator.php
http://www.dragtimes.com/da-density-...calculator.php
very cool link
Safety Car
Joined: Aug 2006
Posts: 4,206
Likes: 6
From: Makena, Maui & NM
I use it all the time. Though the Atco boys claim its bs cuz the weather there is never what Drag Times claims. Its like there is great negative DA in Atco, NJ, just never when they are running there! 
Yet Drag Times DA of MIR is always pretty much spot on, even though there isnt a weather
station near MIR.
Yet Drag Times DA of MIR is always pretty much spot on, even though there isnt a weatherstation near MIR.
Last edited by siffert; Mar 24, 2009 at 10:00 PM.
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Melting Slicks
Joined: Aug 2007
Posts: 2,583
Likes: 415
From: Erwin, NC
hmmm....so my times in WA will be better than what i ran in WI and NC according to that thing. on the same day for the 3 drag strips (pacific, great lakes, and fayetteville respectively) i got:
-91
808
1100
haha, so the -91 is the best?
-91
808
1100
haha, so the -91 is the best?
Safety Car
Joined: Aug 2006
Posts: 4,206
Likes: 6
From: Makena, Maui & NM
in the 1/4 mile, all else being the same.
Team Owner
Joined: Feb 2001
Posts: 27,254
Likes: 136
From: Short Hills, NJ
The tracks are at a little higher elevation of course but they do get crisp cold air and high barometers just like the East and West coasts.
Now if their tracks don't open as early in the season or stay open quite as late in it then that's unfortunate but it has little or nothing to do with who gets better air/more cold fronts/more high pressure systems on average. The physical altitude of a particular track is not variable of course but a cold day at a 400 foot track quite often still provides a lower DA than a hot day at an 80 foot track does.
And of course everyone is still free to roam about this great nation of ours and try out all sorts of tracks/locations if they don't like theirs,
some have even done just that, just ask siffert LOL. 
Team Owner
Joined: Feb 2001
Posts: 27,254
Likes: 136
From: Short Hills, NJ
I use it all the time. Though the Atco boys claim its bs cuz the weather there is never what Drag Times claims. Its like there is great negative DA in Atco, NJ, just never when they are running there! Yet Drag Times DA of MIR is always pretty much spot on, even though there isnt a weather
station near MIR.
Yet Drag Times DA of MIR is always pretty much spot on, even though there isnt a weatherstation near MIR.
I'm curious what the sources that you rely on happen to claim, while you're reading them from your location many hundreds, maybe even thousands, of miles away from Atco of course.
Safety Car
Joined: Aug 2006
Posts: 4,206
Likes: 6
From: Makena, Maui & NM
It was a DA of -400 at Atco today (3/24) at around 4:25pm (though it was much lower earlier in the day), this is an irrefutable and undeniable fact verified by three separate high dollar weather stations and the track's officials/tower themselves. I'm curious what the sources that you rely on
There is nothing irrefutable or undeniable that is was a -2200 to -1200 DA at Atco today.Here was the DA at your 11.75 ride today at 4:00 pm. It was -2200 at 10:00 am at Atco. Confirmed by Accu Weather below too.
I find it hilarious that both of these are always highly accurate for everywhere in the USA except for Atco Dragway, NJ.
ps-any "high dollar" weather station can be easily edited to give higher DA by simply editing the altitude setting to a higher altitude. Voila, instant higher DA all day.
I think the Atco boys are simply embarrased by the terrific negative DA always there. Most C6 Fast records are set at Atco and most Z06 fast records are set at MIR. Duh!
Last edited by siffert; Mar 25, 2009 at 12:05 AM.
Safety Car
Joined: Jan 2008
Posts: 4,711
Likes: 3
From: Middle of No where AK
It gets plenty cold at tracks such as Milan and Gateway, all those Great Lakes cold fronts...it's often very cold in the Chicago area. Southern midwest less so of course.
The tracks are at a little higher elevation of course but they do get crisp cold air and high barometers just like the East and West coasts.
Now if their tracks don't open as early in the season or stay open quite as late in it then that's unfortunate but it has little or nothing to do with who gets better air/more cold fronts/more high pressure systems on average. The physical altitude of a particular track is not variable of course but a cold day at a 400 foot track quite often still provides a lower DA than a hot day at an 80 foot track does.
And of course everyone is still free to roam about this great nation of ours and try out all sorts of tracks/locations if they don't like theirs, some have even done just that, just ask siffert LOL.
The tracks are at a little higher elevation of course but they do get crisp cold air and high barometers just like the East and West coasts.
Now if their tracks don't open as early in the season or stay open quite as late in it then that's unfortunate but it has little or nothing to do with who gets better air/more cold fronts/more high pressure systems on average. The physical altitude of a particular track is not variable of course but a cold day at a 400 foot track quite often still provides a lower DA than a hot day at an 80 foot track does.
And of course everyone is still free to roam about this great nation of ours and try out all sorts of tracks/locations if they don't like theirs,
some have even done just that, just ask siffert LOL. The east and west coast not only have the benefit of elevation but have the benefit of more mild and consistent weather. Last week or so it was 86 one day and 36 the next. Im originally from california and weather like that doesnt exist. The d/a is consistently better at east and west coast tracks. Thats the point Im trying to make. Im not saying I dont ever get good d/a. I personally never get to run with a good d/a due to my job (active duty air force) and lack the ablility to travel at will due to the same circumstances.
Race Director
Joined: Dec 2006
Posts: 12,396
Likes: 2,912
From: Fort Worth, Texas
The east and west coast not only have the benefit of elevation but have the benefit of more mild and consistent weather. Last week or so it was 86 one day and 36 the next. Im originally from california and weather like that doesnt exist. The d/a is consistently better at east and west coast tracks. Thats the point Im trying to make. Im not saying I dont ever get good d/a. I personally never get to run with a good d/a due to my job (active duty air force) and lack the ablility to travel at will due to the same circumstances.
Race Director
Joined: Sep 2007
Posts: 16,557
Likes: 2,108
From: Peoria/Phoenix AZ
C6 of Year Finalist (performance mods) 2019
Why does the track info for Atco show 33 feet elevation? Did someone mean yards?
Google Earth has the start line at 99 feet and the finish at 95 feet. Well within the 1% (13 feet) that NHRA specs.
I've checked several locations on GE and compared to USGS topo maps and never found more than a 2 foot variation.
Google Earth has the start line at 99 feet and the finish at 95 feet. Well within the 1% (13 feet) that NHRA specs.
I've checked several locations on GE and compared to USGS topo maps and never found more than a 2 foot variation.
Safety Car
Joined: May 2000
Posts: 4,827
Likes: 352
From: Albuquerque NM
Our track just opened, it's actual altitude is 5,300 feet but the DA for my runs went from 6,800 feet to 7,300 feet by mid afternoon. Made my 566 SAE rwhp Vette have only an actual 442 to the wheels.
Last edited by 6Speeder; Mar 25, 2009 at 11:31 AM.
Le Mans Master
Joined: Feb 2006
Posts: 5,762
Likes: 4
From: Chandler Arizona
Why does the track info for Atco show 33 feet elevation? Did someone mean yards?
Google Earth has the start line at 99 feet and the finish at 95 feet. Well within the 1% (13 feet) that NHRA specs.
I've checked several locations on GE and compared to USGS topo maps and never found more than a 2 foot variation.
Google Earth has the start line at 99 feet and the finish at 95 feet. Well within the 1% (13 feet) that NHRA specs.
I've checked several locations on GE and compared to USGS topo maps and never found more than a 2 foot variation.
Race Director
Joined: Mar 2005
Posts: 11,549
Likes: 27
From: Southampton NJ
There is nothing irrefutable or undeniable that is was a -2200 to -1200 DA at Atco today.Here was the DA at your 11.75 ride today at 4:00 pm. It was -2200 at 10:00 am at Atco. Confirmed by Accu Weather below too.
I find it hilarious that both of these are always highly accurate for everywhere in the USA except for Atco Dragway, NJ.
ps-any "high dollar" weather station can be easily edited to give higher DA by simply editing the altitude setting to a higher altitude. Voila, instant higher DA all day.
I think the Atco boys are simply embarrased by the terrific negative DA always there. Most C6 Fast records are set at Atco and most Z06 fast records are set at MIR. Duh!
Safety Car
Joined: Aug 2006
Posts: 4,206
Likes: 6
From: Makena, Maui & NM
Last edited by siffert; Mar 25, 2009 at 01:55 PM.