Is there really a one second difference?

Motorhead350

Motorhead350

New member
A member on here PMed me saying his car ran 12.9 here in the midwest and did 11.9 in Florida. Can ocean level really make that much of a difference? So my 12.3 run would be 11.3 down south? Am I really sitting on a 10 second car with race gas if I took it down there? Doubtful.

Opinions, equations, exc please!
 
Heat/Humidity add .75 to your best time. NHRA has an altitude compensator starting at 1,000'.
Ther are conversion formulas out there just like Dyno at SAE vs Standard.

Surprised you do not know this with 9,800+ posts. Are you pulling our chain?
 
sailsmen said:
Heat/Humidity add .75 to your best time. NHRA has an altitude compensator starting at 1,000'.
Ther are conversion formulas out there just like Dyno at SAE vs Standard.

Surprised you do not know this with 9,800+ posts. Are you pulling our chain?
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Yes I was aware, but didn't know if I should believe a whole second. That's the question.
 
Motorhead350 said:
Yes I was aware, but didn't know if I should believe a whole second. That's the question.
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Look up the calculator, and use it, that'll be the best way to check. Sea level tracks are a good deal faster though for sure. a full second seems kinda crazy but maybe he finally got the car to hook properly as well...
 
Use this calculator to get a close estimate:

http://www.dragtimes.com/da-density-altitude-calculator.php

Select track and enter the day you went. click get weather data. Then click the most approximate hour in which you made your pass and click on the red lettering highlighting that hour. The data will automatically input to the calculator . Input your et and mph. Then click Calculate DA.

This normalizes everything to a '0' DA condition. This should be done for any and every pass for comparative purposes. It brings you much closer to what is reality rather than just what is mythology. Its not a perfect conversion, as many other factors are at work during a pass, but as far as eliminating weather conditions on the engine it works rather well.


Here is an example:

2 cars each running 13.50 @ 100 mph. Seems like the same ET, same mph right?
Well, car 1 made its pass with a DA of -1000. Car 2 made its pass at a DA of +1000. A difference of 2000 DA.
See the results below to get an idea of what the 'potential' actually is for each vehicle when DA is normalized.

etdifference.jpg


FWIW most anyone looking at this will fall into the first 2 categories. N/A, the first category. Supercharged/Nitrous/Turbocharged, the second. The 'Extensively modified supercharged/turbocharged' category should really only apply to cars making in excess of ~600 whp with an intercooled supercharger or turbocharger.
 
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The largest difference in the above example was only about 3 tenths, so I don't believe a full second is possible.

HoleyMoley, where do I find a track that's 1000' below sea level? Atlantis?
 
RF Overlord said:
The largest difference in the above example was only about 3 tenths, so I don't believe a full second is possible.

HoleyMoley, where do I find a track that's 1000' below sea level? Atlantis?
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Density Altitude is a calculation of relative humidity, temperature, and actual altitude. Its not uncommon for me to see -1500 near the end of the season at Atco Raceway, which is somewhere around +150 ft absolute altitude (above sea level). Some of those hot and humid summer days we see +3500 to +4000!

If the guy were to race at Bandimere, CO., say, the middle of summer...and ran 12.3 he very well could see 10s if he were to race at a track that saw '0' DA conditions (such as Atco, NJ). Asuming he factored the lower elevation, and lower DA into his tuning when he raced. Hopefully the electronics would be able to compensate. Otherwise he'd be very lean and might not make it down the track ;)

This is an extreme example and not one you'd likely come across too often. In the Rocky Mountains, cars that run 12s are decently fast.

bandimere.jpg
 
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RF Overlord said:
The largest difference in the above example was only about 3 tenths, so I don't believe a full second is possible.

HoleyMoley, where do I find a track that's 1000' below sea level? Atlantis?
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Bob, you ever been to lower Plaquemines Parish, LA?

The area I was working was one of the higher points at -5 ft sea level...;)
 
I many areas with low elevation the heat and humidity far out weighs any advantage. There are only a few days a year in this area when the humidity is low and the temp is low. We rarely get dry cold in this area.

The tracks in this area are Port Allen, Donaldlsonville and Gulf Port. Low areas where they grow cane and rice surrounded by water, almost like Atlantis.;)
 
Dom, what you need to do is go to a little known underground track out in Montana. I do mean underground! It's an old military particle accelerator that was given up by the military at the end of the cold war and turned into a below sea level race track by a group of old school guys from Van Nuys, CA. The track is a mile below sea level which gives you the equivalent of what a 6psi blower would at sea level. From what I've read, you can run an NA car at phenomenal power levels esp. when using a power adder. The only drawback being that at higher speeds, with the air being much more dense, you can't get fast 1/4 mile times. So they run in 1/8 mile runs. It's pretty cool!:beer:
 
RacerX said:
Dom, what you need to do is go to a little known underground track out in Montana. I do mean underground! It's an old military particle accelerator that was given up by the military at the end of the cold war and turned into a below sea level race track by a group of old school guys from Van Nuys, CA. The track is a mile below sea level which gives you the equivalent of what a 6psi blower would at sea level. From what I've read, you can run an NA car at phenomenal power levels esp. when using a power adder. The only drawback being that at higher speeds, with the air being much more dense, you can't get fast 1/4 mile times. So they run in 1/8 mile runs. It's pretty cool!:beer:
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Are there pictures of this? What's the track called? I wanna see!
 
The one track I normally race at is 20 ft above sea level. Cecil co which a lot of people go to is a little more above sea level but they have a downward angle sloped track so people tend to run faster.
 
ctrlraven said:
The one track I normally race at is 20 ft above sea level. Cecil co which a lot of people go to is a little more above sea level but they have a downward angle sloped track so people tend to run faster.
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myth. All NHRA participating tracks do not have this feature. It's an optical illusion, same as with englishtown, nj.
 
The local track I go to is about 2600' above sea level and get DA corrections above 5000' quite often. It can correct E.T.'s to sea lvl well over .6sec some days.
 
I had an ATI blown 396ci 88 Firebird Formula linked just for drags back in 2000. I was running a best of 12.3 at Lebanon Valley Dragway w/603' elevation.

Four days later I was running the exact same setup (even the same gas in the tank) at Atco Raceway w/90' elevation. Ran a consistent 11.5 after cool downs. Granted, it was a tad bit cooler, but I doubt eight tenths in loss contributed to ten degrees.

Atco is notorious for being one of the fastest tracks in the country. Centi blown cars are affected more by this due to heat soak as well as a few other things. The boost levels will climb a bit higher when the blower is cool. That's why meth is almost critical on centi blown cars. Running a smaller pulley will spin the blower faster, generating more heat, causing boost to go down. It's a delicate balancing act.

-Launch variation
-Air temperature
-Wind speed
-Wind direction
-Tire Psi (fronts AND rear)
-Weight difference
-Octane in tank. ( even a 1-2 point octane difference makes a noticeable difference)
-Track Prep
-Track condition
-Track elevation
-Track temperature
-Humidity
-Plug condition ( Heavy nitrous bracket racers sometimes change their plugs after EVERY run )

If applicable......
-Nitrous pressure
-Nitrous bottle temp
-Meth consistency


You will almost never run the same times at different tracks. You need to figure out the nuances of each track if you are serious about getting that power down. There are WAAAY to many contributing factors in regards to an E.T. Aside from the list above, I'm sure I missed a few, but that was my laundry list of check-off items.

In a nutshell, you want the fastest slip time, go to Atco Raceway. Everyone seems to run faster there. I dropped 8 tenths trailering the car 250 miles south, with the exact same setup, and a bit cooler air. Our cars are picky picky, especially centrifigual blown cars.
 
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I saw an interview on Hotrod with the number 1 bracket racer in the country. He said the biggest factor was humidity. My experience concurs with his statement.
NHRA Correction starts at 1,200'
Altitude above Sea Level (Feet) Elapsed Time Factor (ET) Trap Speed Factor (MPH)
1200 .9874 1.0129
 
I run 13.9 at Cecil, Md but i can't for the life of me break 14.3 at lebanon valey, NY. I refuse to go to Lebanon valley for awhile, I get so mad lol
 
I've raced in 8000 DA back in Phoenix. 1 second is quite possible, everything about the car felt like it was a whole lot of agitation for nothing. Still just as loud, still revved like crazy, just didn't go anywhere fast.
 
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