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DA Vs Altitude

Bordercat_797

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#1
Not sure if this is the right spot for my question, but I'll give it a go any way. I've lived here in the high desert of El Paso for a couple of years now, and I have heard several people blame the altitude for s decrease in horsepower and performance. My question is does the altitude supercede or override good DA? I have this DA app on my phone (streets DA) that can use your GPS location to automatically calculate the DA. For example, rightnow it is telling me there is a DA of -512ft in El Paso. Assuming the DA is accurate am I still going to loss power due to high elevation? Thanks for the help and insight.
 

DGatzby

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#2
There are four components. To answer the question you start with your elevation. There the elevation is 3740’. So without anything else you have a 3740’ more of a problem with DA than a guy at sea level.

Given your weather conditions right now; 54 degrees, 30.12 Barameter, 8 degrees dew point (that one right there is a big helper). I got 4089’ DA.
Did you remember to give the app the elevation?

Elevation
Air Temp
Dew Point
Barometer
 

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#3
I used to go to the track when the temp was cool and thought that was all I needed to know. Now with all the apps with all the variables with weather it seems different. This is what happens when you know to much about something and it turns into a science project.

Your DA is a good starting point on when the car should run the best but a high humidity day will be different then a low day also
 
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Bordercat_797

Bordercat_797

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Thread Starter #4
There are four components. To answer the question you start with your elevation. There the elevation is 3740’. So without anything else you have a 3740’ more of a problem with DA than a guy at sea level.

Given your weather conditions right now; 54 degrees, 30.12 Barameter, 8 degrees dew point (that one right there is a big helper). I got 4089’ DA.
Did you remember to give the app the elevation?

Elevation
Air Temp
Dew Point
Barometer
When you select the auto calculate it only ask for the horse power and then uses GPS to calculate DA. I'm not sure if it takes elevation into account.
 
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Bordercat_797

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Thread Starter #5
There are four components. To answer the question you start with your elevation. There the elevation is 3740’. So without anything else you have a 3740’ more of a problem with DA than a guy at sea level.

Given your weather conditions right now; 54 degrees, 30.12 Barameter, 8 degrees dew point (that one right there is a big helper). I got 4089’ DA.
Did you remember to give the app the elevation?

Elevation
Air Temp
Dew Point
Barometer
So basically the app is trash because it doesn't take the elevation into account, therefore giving an incomplete calculation.
 

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Purerock105

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#7
Interesting info for sure. I'm at 4500-5000ft in Reno/Sparks and couldn't find 93 octane anywhere. I then googled. Ah-ha...nobody sells anything higher than 91 in the high elevation areas.

I had absolutely no idea on the "science" between octane and altitude.
 

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#8
When you select the auto calculate it only ask for the horse power and then uses GPS to calculate DA. I'm not sure if it takes elevation into account.
If it is using GPS worth a damn it should have your exact location and, ergo, AASL - it's the weather data components it would be missing unless it's tapping into the nearest FAA / NOTAR or other weather info automatically and just not showing it to you.
 

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#9
Want to get an idea of what difference it makes? Drive the hellcat north to Alamagordo, then take 82 into the Sacramento Mountains. In less than 20 miles you'll be in Cloudcroft with easy access to 8600 to 9000 feet on roads around there. Do a pull in the Tularosa Basin before the climb, and then up in the mountains.
 
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Bordercat_797

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Thread Starter #10
If it is using GPS worth a damn it should have your exact location and, ergo, AASL - it's the weather data components it would be missing unless it's tapping into the nearest FAA / NOTAR or other weather info automatically and just not showing it to you.
Here is a screenshot of what the app tells me the DA is currently. It spits out a projection of what the cars performance should be. However, the numbers aren't even close when you add the elevation.
 

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Bordercat_797

Bordercat_797

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Thread Starter #11
Want to get an idea of what difference it makes? Drive the hellcat north to Alamagordo, then take 82 into the Sacramento Mountains. In less than 20 miles you'll be in Cloudcroft with easy access to 8600 to 9000 feet on roads around there. Do a pull in the Tularosa Basin before the climb, and then up in the mountains.
I just did a rally up to Ruidoso a few weeks ago and definitely noticed the difference in performance at higher elevation.
 

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#12
Ruidoso is about 6900. Beautiful country out there.
 

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#13
Here is a screenshot of what the app tells me the DA is currently. It spits out a projection of what the cars performance should be. However, the numbers aren't even close when you add the elevation.
Try AutoDens app
 

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#14
I moved here to the high desert about 10 years ago...and comparing Cincinnati which is elevation 700 feet to here in Albuquerque at 5350 feet...cars are a full second and 9 mph slower. So do I think I could run a 10.1@134 on a good track in great air with my Redeye? Hell yeah I do.

Everyone here who is serious about drag racing and runs at lower elevation tracks...they always outrun the official NHRA correction factor.
 

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#15
Regarding the relationship of those 4 metrics... In cases where the physical altitude is high, it will be difficult for favorable measures of the other 3 to overcome that.

Many tracks are intentionally built on ground as close to sea level as possible for that reason. In areas like denver and other areas ,it's not possible. That's why you see crazy high DA at bandimere.

In other instances where the track is within a thousand feet of sea level, big baro can trump the altitude and temp on a blower car. Big baro is anything over 30. Many racers, myself included , will adjust their race program to compensate for the environment at a given track.
 

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#16
Just to help out, download Drag Racing Weather app and it will calculate everything for you.

Type in the name of the track and it will show you everything.
 

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