barometric pressure
Safety Car
Joined: Apr 2006
Posts: 4,254
Likes: 5
From: Anaheim Hills, Ca
Wow..this thread really turned into a pissing match.
Now I wish I wouldn't have said I was a pilot
Although, that's probably the only reason that I know anything about b.p., d.a., r.h., dew point ect. But there is one more and that's pressure altitude!
I thought of something regarding density altitude and barometric pressure as it pertains to FI engines. If d.a. is high (less pressure, less dense), the supercharger or turbo will make up for that so therefore no h.p. loss. There is less aerodynamic drag in less dense air. Wouldn't that actually be beneficial in a drag race provided the FI is producing enough boost?
Now I wish I wouldn't have said I was a pilot Although, that's probably the only reason that I know anything about b.p., d.a., r.h., dew point ect. But there is one more and that's pressure altitude!I thought of something regarding density altitude and barometric pressure as it pertains to FI engines. If d.a. is high (less pressure, less dense), the supercharger or turbo will make up for that so therefore no h.p. loss. There is less aerodynamic drag in less dense air. Wouldn't that actually be beneficial in a drag race provided the FI is producing enough boost?
Thread Starter
Race Director
Joined: Mar 2005
Posts: 11,549
Likes: 27
From: Southampton NJ
Wow..this thread really turned into a pissing match. Now I wish I wouldn't have said I was a pilot Although, that's probably the only reason that I know anything about b.p., d.a., r.h., dew point ect. But there is one more and that's pressure altitude!
I thought of something regarding density altitude and barometric pressure as it pertains to FI engines. If d.a. is high (less pressure, less dense), the supercharger or turbo will make up for that so therefore no h.p. loss. There is less aerodynamic drag in less dense air. Wouldn't that actually be beneficial in a drag race provided the FI is producing enough boost?
Now I wish I wouldn't have said I was a pilot Although, that's probably the only reason that I know anything about b.p., d.a., r.h., dew point ect. But there is one more and that's pressure altitude!I thought of something regarding density altitude and barometric pressure as it pertains to FI engines. If d.a. is high (less pressure, less dense), the supercharger or turbo will make up for that so therefore no h.p. loss. There is less aerodynamic drag in less dense air. Wouldn't that actually be beneficial in a drag race provided the FI is producing enough boost?
Premium Supporting Vendor
Joined: Oct 2004
Posts: 23,599
Likes: 1,224
From: Providing the most proven supercharger kits for your C5/6/7 609-752-0321
Wow..this thread really turned into a pissing match. Now I wish I wouldn't have said I was a pilot Although, that's probably the only reason that I know anything about b.p., d.a., r.h., dew point ect. But there is one more and that's pressure altitude!
I thought of something regarding density altitude and barometric pressure as it pertains to FI engines. If d.a. is high (less pressure, less dense), the supercharger or turbo will make up for that so therefore no h.p. loss. There is less aerodynamic drag in less dense air. Wouldn't that actually be beneficial in a drag race provided the FI is producing enough boost?
Now I wish I wouldn't have said I was a pilot Although, that's probably the only reason that I know anything about b.p., d.a., r.h., dew point ect. But there is one more and that's pressure altitude!I thought of something regarding density altitude and barometric pressure as it pertains to FI engines. If d.a. is high (less pressure, less dense), the supercharger or turbo will make up for that so therefore no h.p. loss. There is less aerodynamic drag in less dense air. Wouldn't that actually be beneficial in a drag race provided the FI is producing enough boost?
Actually that's incorrect. A better air day helps out F/I also.
Safety Car
Joined: Apr 2006
Posts: 4,254
Likes: 5
From: Anaheim Hills, Ca
Exactly. One reason that aircraft fly at the altitudes they do is because of the thinner air, therefore true airspeed is higher. Think of the extreme: If in a vacuum, as in above the atmosphere, there is no aerodynamic drag. Higher altitudes are closer to a vacuum than lower altitudes
Safety Car
Joined: Apr 2006
Posts: 4,254
Likes: 5
From: Anaheim Hills, Ca
Only if the there is no limitation on the amount of boost ie; waste gate. If the forced induction is set to a specific pounds of boost, it shouldn't make a difference. Humidity will though. But Hey, I'm NO tuner so I might be off base here.
Last edited by JJC5; Nov 18, 2008 at 05:34 PM.
Thread Starter
Race Director
Joined: Mar 2005
Posts: 11,549
Likes: 27
From: Southampton NJ
Exactly. One reason that aircraft fly at the altitudes they do is because of the thinner air, therefore true airspeed is higher. Think of the extreme: If in a vacuum, as in above the atmosphere, there is no aerodynamic drag. Higher altitudes are closer to a vacuum than lower altitudes
so then they could get a +1000 da and we could have a+1000 da and they would be faster because of thinner air and less humidity,
Safety Car
Joined: Apr 2006
Posts: 4,254
Likes: 5
From: Anaheim Hills, Ca
You're saying at +1000 da at both places, and they would still be faster? Density altitude is density altitude.
Actually, re-reading your post, it's +1000 at each place so yes, that theory would be right because of their higher elevation to begin with. (I need to get back to work!!)
Last edited by JJC5; Nov 18, 2008 at 05:58 PM.
Pro
Joined: May 2007
Posts: 585
Likes: 0
From: Ocean County NJ
Wow..this thread really turned into a pissing match. Now I wish I wouldn't have said I was a pilot Although, that's probably the only reason that I know anything about b.p., d.a., r.h., dew point ect. But there is one more and that's pressure altitude!
I thought of something regarding density altitude and barometric pressure as it pertains to FI engines. If d.a. is high (less pressure, less dense), the supercharger or turbo will make up for that so therefore no h.p. loss. There is less aerodynamic drag in less dense air. Wouldn't that actually be beneficial in a drag race provided the FI is producing enough boost?
Now I wish I wouldn't have said I was a pilot Although, that's probably the only reason that I know anything about b.p., d.a., r.h., dew point ect. But there is one more and that's pressure altitude!I thought of something regarding density altitude and barometric pressure as it pertains to FI engines. If d.a. is high (less pressure, less dense), the supercharger or turbo will make up for that so therefore no h.p. loss. There is less aerodynamic drag in less dense air. Wouldn't that actually be beneficial in a drag race provided the FI is producing enough boost?
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Safety Car
Joined: Apr 2006
Posts: 4,254
Likes: 5
From: Anaheim Hills, Ca
I agree with that. Instead of the intake manifold in a N/A engine having a slight vacuum (low pressure) at wide open throttle, the F/I unit, turbo or supercharger, can bring it to zero vacuum or usually positive pressure. So it is making its own atmosphere. If the supercharger makes 10 lbs of positive boost, my thinking is that it should make the same manifold pressure if the b.p. is 29.92 or 30.02. If the professional tuners say that the F/I engines like the better air though, I'll go with them and believe that.
Thread Starter
Race Director
Joined: Mar 2005
Posts: 11,549
Likes: 27
From: Southampton NJ
yes it helps a better air day, but in a worse air fi its less noticeable, the bad air that is
Pro
Joined: May 2007
Posts: 585
Likes: 0
From: Ocean County NJ
Airpuss in Red, me in Black
Bull****, otherwise you wouldn't have opened your little mouth, but thanks for the thoughtful contribution
If you agreed with my DA explanation then you must agree that is not just 20 rwhp, figure 3% per 1000' DA power increase over worse DA, whatever that may be.
Again, your arrogance is assuming I agreed. I never said I agreed with your calculation. I thanked you for your explanation. I will now retract the thanks so as not to cause you further confusion.
Welcome to the club, and since you have a forced induction car you should also be aware that DA isn't near a major player because FI cars make their own atmosphere. Reread what I just said, I didn't say it didn't matter, but that the power differences between different DA's is not 3%, far less. I've owned a twin turbo LS2.
Had a forced induction car. As I said in a prior post (without reading yours first), I agreed that FI cars create their own atmosphere. Finally we agree on something.
I will if you'll stop crying, please. lol
Haven't cried yet Airpuss, just trying to point out that DA is not everything, something you have insinutated as being the sole reason for Dennis breaking into the 10's.
Actually I was tired of trying to read text that someone was too lazy to proofread and the run on sentences made little sense.
Next time, maybe I will abandon punctuation altogether. I did not realize that my paper was being graded.
And I'll return the favor, you're acting like an idiot that felt so self important he had to inject himself in this discussion.
Thanks for pointing out what I already acknowledged, Capt. Obvious.
I never said it was, but the oversensitive types, like yourself, like to read into it as some sort of personal attack then try and take what I said to the illogical extreme or totally take what I said out of context, including just making up what I said.
Funny, I never took it as a personal attack. I read what you wrote and chose to disagree. I took offense to you challenging the intelligence of others because you think that you are the all knowing pilot. Just because you fly near G-D does not mean you are G-D.
Because it's so difficult to drive an automatic transmission car? There are plenty of variables, never disputed that, but you cannot deny the effects of DA without looking like an idiot. But you're doing a good job.
Actually its a paddle shifted car. If it looks so easy to you, get yourself a ride in F-1. Let me know how that works out for you.
Dude, don't go away mad. Just go away.
Bull****, otherwise you wouldn't have opened your little mouth, but thanks for the thoughtful contribution
If you agreed with my DA explanation then you must agree that is not just 20 rwhp, figure 3% per 1000' DA power increase over worse DA, whatever that may be.
Again, your arrogance is assuming I agreed. I never said I agreed with your calculation. I thanked you for your explanation. I will now retract the thanks so as not to cause you further confusion.
Welcome to the club, and since you have a forced induction car you should also be aware that DA isn't near a major player because FI cars make their own atmosphere. Reread what I just said, I didn't say it didn't matter, but that the power differences between different DA's is not 3%, far less. I've owned a twin turbo LS2.
Had a forced induction car. As I said in a prior post (without reading yours first), I agreed that FI cars create their own atmosphere. Finally we agree on something.
I will if you'll stop crying, please. lol
Haven't cried yet Airpuss, just trying to point out that DA is not everything, something you have insinutated as being the sole reason for Dennis breaking into the 10's.
Actually I was tired of trying to read text that someone was too lazy to proofread and the run on sentences made little sense.
Next time, maybe I will abandon punctuation altogether. I did not realize that my paper was being graded.
And I'll return the favor, you're acting like an idiot that felt so self important he had to inject himself in this discussion.
Thanks for pointing out what I already acknowledged, Capt. Obvious.
I never said it was, but the oversensitive types, like yourself, like to read into it as some sort of personal attack then try and take what I said to the illogical extreme or totally take what I said out of context, including just making up what I said.
Funny, I never took it as a personal attack. I read what you wrote and chose to disagree. I took offense to you challenging the intelligence of others because you think that you are the all knowing pilot. Just because you fly near G-D does not mean you are G-D.
Because it's so difficult to drive an automatic transmission car? There are plenty of variables, never disputed that, but you cannot deny the effects of DA without looking like an idiot. But you're doing a good job.
Actually its a paddle shifted car. If it looks so easy to you, get yourself a ride in F-1. Let me know how that works out for you.
Dude, don't go away mad. Just go away.
Le Mans Master<br><img src="/forums/images/ranks/5k-6k.gif" border="0">
Joined: May 2007
Posts: 5,404
Likes: 1
St. Jude Donor '08-'09
Le Mans Master<br><img src="/forums/images/ranks/5k-6k.gif" border="0">
Joined: May 2007
Posts: 5,404
Likes: 1
St. Jude Donor '08-'09
Thread Starter
Race Director
Joined: Mar 2005
Posts: 11,549
Likes: 27
From: Southampton NJ
but i never been at atco in a tall wind if i am you think propping the hatch up will help
Le Mans Master<br><img src="/forums/images/ranks/5k-6k.gif" border="0">
Joined: May 2007
Posts: 5,404
Likes: 1
St. Jude Donor '08-'09
Melting Slicks
Joined: Feb 2004
Posts: 3,307
Likes: 111
From: Tucson AZ
Density altitude (DA) does have a huge affect on engine performance
Density altitude (DA) does have a huge affect on engine performance. Look at the NHRA times in Denver vs Englishtown. Most dyno's are set up to automatically correct for standard day (that's usually how they fudge the numbers).
I have raced at Atco and Englishtown as well as Firebird Phoenix and SIR Tucson and there is a huge difference. We typically log DA of 0 to -1000' in NJ and Firebird is usually around 3000'. Tucson gets up to 7000' in the summer because the elevation is at 3000'MSL and the temps are over 100. Las Vegas and Boise are also high where as Pomona, Sonoma, and Seattle are great.
For the race cars we compute and log DA for every pass. We use a trailer mounted weather station with a pager that pages us the updated weather every 5 minutes.
Below is the NHRA altitude correction factor table. It adjusts for elevation only and does not account for temp. Also notice that supercharged and turbocharged adjustments are 1/2 that of the normally aspirated cars.
NHRA altitude correction factors
Below are the NHRA Altitude Correction formulas for all sportsman categories for NHRA member tracks that are classified as altitude facilities:
NHRA ALTITUDE CORRECTION FACTORS
Comp, S/C, S/G, S/ST
Convert to Sea Level Convert to Altitude
Track Name Alt ET MPH 1/2ET 1/2MPH ET MPH 1/2ET 1/2MPH
DIVISION 4
Amarillo, TX 3700 .9646 1.0337 .9823 1.0168 1.0367 .9674 1.0180 .9834
Roswell, NM 3700 .9646 1.0337 .9823 1.0168 1.0367 .9674 1.0180 .9834
DIVISION 5
Denver, CO 5800 .9405 1.0563 .9702 1.0281 1.0633 .9467 1.0307 .9726
Douglas, WY 4900 .9508 1.0466 .9754 1.0233 1.0517 .9555 1.0252 .9772
Grand Junction, CO 4800 .9520 1.0455 .9760 1.0228 1.0504 .9565 1.0246 .9777
Great Bend, KS 1900 .9853 1.0143 .9927 1.0072 1.0149 .9859 1.0074 .9929
Julesburg, CO 3500 .9669 1.0315 .9835 1.0158 1.0342 .9694 1.0168 .9845
Pierre, S.D. 1700 .9876 1.0122 .9938 1.0061 1.0126 .9880 1.0062 .9940
Pueblo, CO 4900 .9508 1.0466 .9754 1.0233 1.0517 .9555 1.0252 .9772
DIVISION 6
Acton, MT 3700 .9646 1.0337 .9823 1.0168 1.0367 .9674 1.0180 .9834
Anaconda, MT 5100 .9485 1.0488 .9743 1.0244 1.0543 .9535 1.0264 .9762
Ashcroft, CAN 1700 .9876 1.0122 .9938 1.0061 1.0126 .9880 1.0062 .9940
Boise, ID 2700 .9761 1.0229 .9881 1.0115 1.0245 .9776 1.0121 .9887
Lewistown, MT 4100 .9600 1.0380 .9800 1.0190 1.0416 .9634 1.0204 .9814
Medicine Hat, CAN 2400 .9796 1.0197 .9898 1.0098 1.0209 .9807 1.0103 .9903
Prince George, BC 2200 .9819 1.0175 .9909 1.0088 1.0185 .9828 1.0092 .9913
Saskatoon, CAN 1600 .9888 1.0111 .9944 1.0055 1.0114 .9890 1.0057 .9945
DIVISION 7
Albuquerque, NM 5400 .9451 1.0520 .9725 1.0260 1.0581 .9506 1.0282 .9747
Fallon, NV 4000 .9612 1.0369 .9806 1.0185 1.0404 .9644 1.0198 .9819
Inyokern, CA 2400 .9796 1.0197 .9898 1.0098 1.0209 .9807 1.0103 .9903
Las Vegas, NV 2100 .9830 1.0165 .9915 1.0082 1.0173 .9838 1.0086 .9918
Palmdale, CA 2700 .9761 1.0229 .9881 1.0115 1.0245 .9776 1.0121 .9887
Salt Lake, UT 4400 .9566 1.0412 .9783 1.0206 1.0454 .9604 1.0222 .9798
Tucson, AZ 3000 .9727 1.0262 .9863 1.0131 1.0281 .9745 1.0139 .9871
NOTE: Supercharged and/or turbocharged cars (i.e.: AA/A, AA/AT, BB/A, BB/AT, A/PM and AA/PM) use half factor; TA/D and TA/FC cars are not factored.
I have raced at Atco and Englishtown as well as Firebird Phoenix and SIR Tucson and there is a huge difference. We typically log DA of 0 to -1000' in NJ and Firebird is usually around 3000'. Tucson gets up to 7000' in the summer because the elevation is at 3000'MSL and the temps are over 100. Las Vegas and Boise are also high where as Pomona, Sonoma, and Seattle are great.
For the race cars we compute and log DA for every pass. We use a trailer mounted weather station with a pager that pages us the updated weather every 5 minutes.
Below is the NHRA altitude correction factor table. It adjusts for elevation only and does not account for temp. Also notice that supercharged and turbocharged adjustments are 1/2 that of the normally aspirated cars.
NHRA altitude correction factors
Below are the NHRA Altitude Correction formulas for all sportsman categories for NHRA member tracks that are classified as altitude facilities:
NHRA ALTITUDE CORRECTION FACTORS
Comp, S/C, S/G, S/ST
Convert to Sea Level Convert to Altitude
Track Name Alt ET MPH 1/2ET 1/2MPH ET MPH 1/2ET 1/2MPH
DIVISION 4
Amarillo, TX 3700 .9646 1.0337 .9823 1.0168 1.0367 .9674 1.0180 .9834
Roswell, NM 3700 .9646 1.0337 .9823 1.0168 1.0367 .9674 1.0180 .9834
DIVISION 5
Denver, CO 5800 .9405 1.0563 .9702 1.0281 1.0633 .9467 1.0307 .9726
Douglas, WY 4900 .9508 1.0466 .9754 1.0233 1.0517 .9555 1.0252 .9772
Grand Junction, CO 4800 .9520 1.0455 .9760 1.0228 1.0504 .9565 1.0246 .9777
Great Bend, KS 1900 .9853 1.0143 .9927 1.0072 1.0149 .9859 1.0074 .9929
Julesburg, CO 3500 .9669 1.0315 .9835 1.0158 1.0342 .9694 1.0168 .9845
Pierre, S.D. 1700 .9876 1.0122 .9938 1.0061 1.0126 .9880 1.0062 .9940
Pueblo, CO 4900 .9508 1.0466 .9754 1.0233 1.0517 .9555 1.0252 .9772
DIVISION 6
Acton, MT 3700 .9646 1.0337 .9823 1.0168 1.0367 .9674 1.0180 .9834
Anaconda, MT 5100 .9485 1.0488 .9743 1.0244 1.0543 .9535 1.0264 .9762
Ashcroft, CAN 1700 .9876 1.0122 .9938 1.0061 1.0126 .9880 1.0062 .9940
Boise, ID 2700 .9761 1.0229 .9881 1.0115 1.0245 .9776 1.0121 .9887
Lewistown, MT 4100 .9600 1.0380 .9800 1.0190 1.0416 .9634 1.0204 .9814
Medicine Hat, CAN 2400 .9796 1.0197 .9898 1.0098 1.0209 .9807 1.0103 .9903
Prince George, BC 2200 .9819 1.0175 .9909 1.0088 1.0185 .9828 1.0092 .9913
Saskatoon, CAN 1600 .9888 1.0111 .9944 1.0055 1.0114 .9890 1.0057 .9945
DIVISION 7
Albuquerque, NM 5400 .9451 1.0520 .9725 1.0260 1.0581 .9506 1.0282 .9747
Fallon, NV 4000 .9612 1.0369 .9806 1.0185 1.0404 .9644 1.0198 .9819
Inyokern, CA 2400 .9796 1.0197 .9898 1.0098 1.0209 .9807 1.0103 .9903
Las Vegas, NV 2100 .9830 1.0165 .9915 1.0082 1.0173 .9838 1.0086 .9918
Palmdale, CA 2700 .9761 1.0229 .9881 1.0115 1.0245 .9776 1.0121 .9887
Salt Lake, UT 4400 .9566 1.0412 .9783 1.0206 1.0454 .9604 1.0222 .9798
Tucson, AZ 3000 .9727 1.0262 .9863 1.0131 1.0281 .9745 1.0139 .9871
NOTE: Supercharged and/or turbocharged cars (i.e.: AA/A, AA/AT, BB/A, BB/AT, A/PM and AA/PM) use half factor; TA/D and TA/FC cars are not factored.
Drifting
Joined: Jan 2008
Posts: 1,529
Likes: 23
Thank You. Enough Said.
Density altitude (DA) does have a huge affect on engine performance. Look at the NHRA times in Denver vs Englishtown. Most dyno's are set up to automatically correct for standard day (that's usually how they fudge the numbers).
I have raced at Atco and Englishtown as well as Firebird Phoenix and SIR Tucson and there is a huge difference. We typically log DA of 0 to -1000' in NJ and Firebird is usually around 3000'. Tucson gets up to 7000' in the summer because the elevation is at 3000'MSL and the temps are over 100. Las Vegas and Boise are also high where as Pomona, Sonoma, and Seattle are great.
For the race cars we compute and log DA for every pass. We use a trailer mounted weather station with a pager that pages us the updated weather every 5 minutes.
Below is the NHRA altitude correction factor table. It adjusts for elevation only and does not account for temp. Also notice that supercharged and turbocharged adjustments are 1/2 that of the normally aspirated cars.
NHRA altitude correction factors
Below are the NHRA Altitude Correction formulas for all sportsman categories for NHRA member tracks that are classified as altitude facilities:
NHRA ALTITUDE CORRECTION FACTORS
Comp, S/C, S/G, S/ST
Convert to Sea Level Convert to Altitude
Track Name Alt ET MPH 1/2ET 1/2MPH ET MPH 1/2ET 1/2MPH
DIVISION 4
Amarillo, TX 3700 .9646 1.0337 .9823 1.0168 1.0367 .9674 1.0180 .9834
Roswell, NM 3700 .9646 1.0337 .9823 1.0168 1.0367 .9674 1.0180 .9834
DIVISION 5
Denver, CO 5800 .9405 1.0563 .9702 1.0281 1.0633 .9467 1.0307 .9726
Douglas, WY 4900 .9508 1.0466 .9754 1.0233 1.0517 .9555 1.0252 .9772
Grand Junction, CO 4800 .9520 1.0455 .9760 1.0228 1.0504 .9565 1.0246 .9777
Great Bend, KS 1900 .9853 1.0143 .9927 1.0072 1.0149 .9859 1.0074 .9929
Julesburg, CO 3500 .9669 1.0315 .9835 1.0158 1.0342 .9694 1.0168 .9845
Pierre, S.D. 1700 .9876 1.0122 .9938 1.0061 1.0126 .9880 1.0062 .9940
Pueblo, CO 4900 .9508 1.0466 .9754 1.0233 1.0517 .9555 1.0252 .9772
DIVISION 6
Acton, MT 3700 .9646 1.0337 .9823 1.0168 1.0367 .9674 1.0180 .9834
Anaconda, MT 5100 .9485 1.0488 .9743 1.0244 1.0543 .9535 1.0264 .9762
Ashcroft, CAN 1700 .9876 1.0122 .9938 1.0061 1.0126 .9880 1.0062 .9940
Boise, ID 2700 .9761 1.0229 .9881 1.0115 1.0245 .9776 1.0121 .9887
Lewistown, MT 4100 .9600 1.0380 .9800 1.0190 1.0416 .9634 1.0204 .9814
Medicine Hat, CAN 2400 .9796 1.0197 .9898 1.0098 1.0209 .9807 1.0103 .9903
Prince George, BC 2200 .9819 1.0175 .9909 1.0088 1.0185 .9828 1.0092 .9913
Saskatoon, CAN 1600 .9888 1.0111 .9944 1.0055 1.0114 .9890 1.0057 .9945
DIVISION 7
Albuquerque, NM 5400 .9451 1.0520 .9725 1.0260 1.0581 .9506 1.0282 .9747
Fallon, NV 4000 .9612 1.0369 .9806 1.0185 1.0404 .9644 1.0198 .9819
Inyokern, CA 2400 .9796 1.0197 .9898 1.0098 1.0209 .9807 1.0103 .9903
Las Vegas, NV 2100 .9830 1.0165 .9915 1.0082 1.0173 .9838 1.0086 .9918
Palmdale, CA 2700 .9761 1.0229 .9881 1.0115 1.0245 .9776 1.0121 .9887
Salt Lake, UT 4400 .9566 1.0412 .9783 1.0206 1.0454 .9604 1.0222 .9798
Tucson, AZ 3000 .9727 1.0262 .9863 1.0131 1.0281 .9745 1.0139 .9871
NOTE: Supercharged and/or turbocharged cars (i.e.: AA/A, AA/AT, BB/A, BB/AT, A/PM and AA/PM) use half factor; TA/D and TA/FC cars are not factored.
I have raced at Atco and Englishtown as well as Firebird Phoenix and SIR Tucson and there is a huge difference. We typically log DA of 0 to -1000' in NJ and Firebird is usually around 3000'. Tucson gets up to 7000' in the summer because the elevation is at 3000'MSL and the temps are over 100. Las Vegas and Boise are also high where as Pomona, Sonoma, and Seattle are great.
For the race cars we compute and log DA for every pass. We use a trailer mounted weather station with a pager that pages us the updated weather every 5 minutes.
Below is the NHRA altitude correction factor table. It adjusts for elevation only and does not account for temp. Also notice that supercharged and turbocharged adjustments are 1/2 that of the normally aspirated cars.
NHRA altitude correction factors
Below are the NHRA Altitude Correction formulas for all sportsman categories for NHRA member tracks that are classified as altitude facilities:
NHRA ALTITUDE CORRECTION FACTORS
Comp, S/C, S/G, S/ST
Convert to Sea Level Convert to Altitude
Track Name Alt ET MPH 1/2ET 1/2MPH ET MPH 1/2ET 1/2MPH
DIVISION 4
Amarillo, TX 3700 .9646 1.0337 .9823 1.0168 1.0367 .9674 1.0180 .9834
Roswell, NM 3700 .9646 1.0337 .9823 1.0168 1.0367 .9674 1.0180 .9834
DIVISION 5
Denver, CO 5800 .9405 1.0563 .9702 1.0281 1.0633 .9467 1.0307 .9726
Douglas, WY 4900 .9508 1.0466 .9754 1.0233 1.0517 .9555 1.0252 .9772
Grand Junction, CO 4800 .9520 1.0455 .9760 1.0228 1.0504 .9565 1.0246 .9777
Great Bend, KS 1900 .9853 1.0143 .9927 1.0072 1.0149 .9859 1.0074 .9929
Julesburg, CO 3500 .9669 1.0315 .9835 1.0158 1.0342 .9694 1.0168 .9845
Pierre, S.D. 1700 .9876 1.0122 .9938 1.0061 1.0126 .9880 1.0062 .9940
Pueblo, CO 4900 .9508 1.0466 .9754 1.0233 1.0517 .9555 1.0252 .9772
DIVISION 6
Acton, MT 3700 .9646 1.0337 .9823 1.0168 1.0367 .9674 1.0180 .9834
Anaconda, MT 5100 .9485 1.0488 .9743 1.0244 1.0543 .9535 1.0264 .9762
Ashcroft, CAN 1700 .9876 1.0122 .9938 1.0061 1.0126 .9880 1.0062 .9940
Boise, ID 2700 .9761 1.0229 .9881 1.0115 1.0245 .9776 1.0121 .9887
Lewistown, MT 4100 .9600 1.0380 .9800 1.0190 1.0416 .9634 1.0204 .9814
Medicine Hat, CAN 2400 .9796 1.0197 .9898 1.0098 1.0209 .9807 1.0103 .9903
Prince George, BC 2200 .9819 1.0175 .9909 1.0088 1.0185 .9828 1.0092 .9913
Saskatoon, CAN 1600 .9888 1.0111 .9944 1.0055 1.0114 .9890 1.0057 .9945
DIVISION 7
Albuquerque, NM 5400 .9451 1.0520 .9725 1.0260 1.0581 .9506 1.0282 .9747
Fallon, NV 4000 .9612 1.0369 .9806 1.0185 1.0404 .9644 1.0198 .9819
Inyokern, CA 2400 .9796 1.0197 .9898 1.0098 1.0209 .9807 1.0103 .9903
Las Vegas, NV 2100 .9830 1.0165 .9915 1.0082 1.0173 .9838 1.0086 .9918
Palmdale, CA 2700 .9761 1.0229 .9881 1.0115 1.0245 .9776 1.0121 .9887
Salt Lake, UT 4400 .9566 1.0412 .9783 1.0206 1.0454 .9604 1.0222 .9798
Tucson, AZ 3000 .9727 1.0262 .9863 1.0131 1.0281 .9745 1.0139 .9871
NOTE: Supercharged and/or turbocharged cars (i.e.: AA/A, AA/AT, BB/A, BB/AT, A/PM and AA/PM) use half factor; TA/D and TA/FC cars are not factored.
Le Mans Master<br><img src="/forums/images/ranks/5k-6k.gif" border="0">
Joined: May 2007
Posts: 5,404
Likes: 1
St. Jude Donor '08-'09
Density altitude (DA) does have a huge affect on engine performance. Look at the NHRA times in Denver vs Englishtown. Most dyno's are set up to automatically correct for standard day (that's usually how they fudge the numbers).
I have raced at Atco and Englishtown as well as Firebird Phoenix and SIR Tucson and there is a huge difference. We typically log DA of 0 to -1000' in NJ and Firebird is usually around 3000'. Tucson gets up to 7000' in the summer because the elevation is at 3000'MSL and the temps are over 100. Las Vegas and Boise are also high where as Pomona, Sonoma, and Seattle are great.
For the race cars we compute and log DA for every pass. We use a trailer mounted weather station with a pager that pages us the updated weather every 5 minutes.
I have raced at Atco and Englishtown as well as Firebird Phoenix and SIR Tucson and there is a huge difference. We typically log DA of 0 to -1000' in NJ and Firebird is usually around 3000'. Tucson gets up to 7000' in the summer because the elevation is at 3000'MSL and the temps are over 100. Las Vegas and Boise are also high where as Pomona, Sonoma, and Seattle are great.
For the race cars we compute and log DA for every pass. We use a trailer mounted weather station with a pager that pages us the updated weather every 5 minutes.
Let me ask you this. Are the DA's in NJ lower than the rest of the USA, on average? Is it true that running your car in NJ as opposed to the majority of states will result in faster times? If this is true, then we'll have found ONE good thing about NJ.
