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This is a discussion on Conversions within the Motorsports Talk forums, part of the Community - Meet other Enthusiasts category; The track i drag at is at 830 ft above sea level. The day i was there was about 92-95 ...

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    Registered User tom'sti's Avatar
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    The track i drag at is at 830 ft above sea level. The day i was there was about 92-95 F in about 80% humidity. This was my second time at the track and i ran a 13.7. How can i convert this to tell how i'd run against people here posting times at sea level on cooler days with less humidity? Just curious.
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    Moderator YBNormal07's Avatar
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    There are various formulas you can use. Try googling "altitude correction factor" and you should find a few of them. FWIW, I don't believe the NHRA even offers a correction factor for anything less than 1200 ft above sea level. You are probably looking at less than a 10th in time and less and .2 mph difference at sea level. For a cooler day, you might get some improvement also, but the barametric pressure has a much larger effect.
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    Buzzz Wannabe's Avatar
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    Barometric pressure is way more important in a naturally aspirated deal. The same with the NHRA adjustments for stock, super stock and comp eliminator, as well as the general adjustment for super categories. When you throw a turbo (or blower or nitrous) then the average correction factors are thrown out the window.
    The standard correction factor is 60 degrees f, barometric pressure of 29.92 at sea level with 0% humidity. So any basic correction factor will be to this number. But part of the problem is that this number NEVER occurs in real life. So becomes a mute point.
    You total corrector will throw you to around a 13.3 to the perfect correction. (assuming everything else remains identical.) But again, a decent dry sea level day you are looking at losing around 2 tenths. Most of that will be humidity in the factor.
    Did I confuse everyone else, or just confused myself?

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    Moderator YBNormal07's Avatar
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    Quote Originally Posted by Wannabe View Post
    Barometric pressure is way more important in a naturally aspirated deal. The same with the NHRA adjustments for stock, super stock and comp eliminator, as well as the general adjustment for super categories. When you throw a turbo (or blower or nitrous) then the average correction factors are thrown out the window.
    The standard correction factor is 60 degrees f, barometric pressure of 29.92 at sea level with 0% humidity. So any basic correction factor will be to this number. But part of the problem is that this number NEVER occurs in real life. So becomes a mute point.
    You total corrector will throw you to around a 13.3 to the perfect correction. (assuming everything else remains identical.) But again, a decent dry sea level day you are looking at losing around 2 tenths. Most of that will be humidity in the factor.
    Did I confuse everyone else, or just confused myself?
    Care to show the basic math behind this? Or just theorize it out? I'm curious as having raced at various altitudes and different weather conditions, that seems to be a pretty aggressive correction...just imho of course. Always willing to learn something new
    tEh PriUs=teH faSTah!@@!
    08 Audi S5 Black Diamond edition
    SOLD: 05 SWP Legacy GT Limited 5MT, 13.3ish@105 (stage 2) crappy stock clutch
    SOLD: 04 MPS/SW WRX Sti. 12.971 @ 103.97 (stock)
    278 AWHP/283 AWT, Catback exhaust
    306 AWHP/341 AWT, Stage 2
    (Scott) Moderator-STi, Drag Racing, Car Purchasing, and Tutorial Forums

  6. #5
    Buzzz Wannabe's Avatar
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    Some of the best stuff in the way of mathmatics is on dynomometer sites, as dynos are always adapting horsepower to stable. That math is easy. But when you get into adapting that with a race track. And even worse, turbochargers with variable timing devices, it gets absolutely hairy.
    http://www.land-and-sea.com/dyno-tec...horsepower.htm
    Here is one from my dyno manufacturer.

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