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Discussion Starter #1
Paul (strider7) and I were out at the 1/4 mi track one evening and it was just hot and sticky as hell. Everyone was complaining about it, so naturally I got curious about how much the humidity and temp really matter. Well, I found a page that calculates a correction factor for less than perfect atmospheric conditions like we had to deal with. I wasnt sure it would matter much on our times, but it is a noticeable if not significant correction afterall. Basically our air wasnt very dense.

http://www.prestage.com/carmath/calc_etcorrect_to_standard.asp

on this site, it also has something to correct for elevation, at atleast we dont have to worry about that!

If you want to get into the calculations a little bit, this guy does some interesting stuff, although I havent looked into it enough to see if he did anything wrong it seems pretty good:
http://www.webtripper.com/automotive/tech/

P.S. Barometric pressure is defined as atmospheric pressure i.e. the force exerted on a surface of unit area caused by the weight of the air column above

Some more calcs I found:
Correction Factor for ET = 0.9986 + 0.0095 * (CorrBaro - 29.1) - 0.0002556*(Temp - 35.0)

Correction Factor for MPH = 1.0003525 - 0.00975 * (CorrBaro - 29.1) + 0.0002667*(Temp - 35.0)

For Correction TO Standard:
Et = EtOld * cfet
Mph = MphOld * cfmph

These equations were obtained from a empirically-derived correction chart, which was fitted to the above form (least-squares).

I used some old timeslip data with typical conditions and the answer I get is reasonable.

P.S.S. Temp in deg F and Pressure in mmHg
 

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This is very similar to what is done with dynos when they correct for SAE power. What's funny is that everyone puts trust in SAE corrected dynos yet most will push aside someone if they give a corrected timeslip based on elevation, temp, pressure etc.
 

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Discussion Starter #3
Really? I havent had any experience with that, but what is supposed to be the difference in thought? I dont bother to claim corrected timeslips because it doesnt usually matter more than 1 tenth of a second.
 

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Sometimes it makes a big difference. I corrected my ET with my stock R at 14.9 at it came out to be 14.5. With elevation alone it dropped 14.7. Everyone's looking for those few tenths, but surprisingly it just doesn't fly with most people. Probably because most people don't have all the needed information on their timeslips to correct it so then it just doesn't exist to them.

But I don't know, some tracks seem slow and everyone gets bad times that day. That's why I've never liked arguing who's car is faster based evem 0on timeslips. You never know what the track conditions were like that day for both. I think correction factors are a good way to even the playing field a bit.
 

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Glad I popped in and saw this ... I was wondering where you were Adam, and when you were gonna come up with this. Thanks!

Did you ever get pics back from the last time we went to HRP? (Don't know if you have a film camera or a digital).

And ... check the timeslips section ... mine are up.
Make sure to see my #5 slip! (It's my 'fastest gun in the West' r/t slip
)
 

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But if your both at the track your in the same conditions, I don't know about correcting slips, its like if a football team loses to another by 40 points in bad weather. Do they facter that in and say," well, do to the elements you really only lost by 10 points"? Does that really make you feel better about your times?
 

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Discussion Starter #7
Well, if you add some performance mods and your times get slower because of terrible conditions, different track, etc its nice peace of mind to know that you actually were making more power. It doesnt really matter if youre simply racing heads up. one reason why correcting my times only helps a tenth or two for me is that my track is at sea level. Another way that understanding the air quality (density) is important is that you can (if you have the tools and experience) more aggresively tune your engine package (ie turn up boost, compression, etc.) for less dense air because of elevation, humidity, and temperature.
 

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Way to to tell him Adam !!! (j/k Pollux)


But, there really are good reasons to do this. Another that Adam didn't mention specifically is that it serves as an equalizer for all of us. We can be effectively correct in comparing our et's with those of members from around the country and the world ... and all because these formulas level the playing field by working 'backwards' to remove the effects of elevation and weather variables from our 1320 statistics.

Equalization is a good thing.
 

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Oh Adam, BTW ...

What numbers did you enter for that night of Aug. 9th ...

I don't know what to enter into the formula. I figure it was 90% humidity, but I don't know about the temp.

Thanks
 

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I just think if your a serious tuner and you tune your car properly, you are going to know that different weather conditions are going to affect your times and its not really nessasary to justify it with formulas to figure out "what if" times. Don't get me wrong, I'm not trying to be a dick or anything and I don't think its a bad thing to figure out formulas and what not. But what are you really gaining? A piece of mind? Lets not be so insecure about our times, thats part of the fun.
 

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I don't know what to say Pollux ... I guess you just don't 'get' it.
Oh well, at least you drive a Teg.


It's not about 'what ifs', piece of mind, or insecurity (I can romp all over you ANY DAY 'O THA WEEK) (ha,ha ... just joking ... but you know I can)
It's like I said, it just serves as an equalizer for people who live in different places and have different climatic variables ... such as humidity, temperature, and elevation. It allows us to compare our times on a somewhat levelized field, if you will.

So ... go out there and get some timeslips already! And post 'em up for cryin out loud.
 

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Pollux on Aug/24/02 said:
But if your both at the track your in the same conditions, I don't know about correcting slips, its like if a football team loses to another by 40 points in bad weather. Do they facter that in and say," well, do to the elements you really only lost by 10 points"? Does that really make you feel better about your times?
If you are both at the same track with the same conditions then it wouldn't make a difference corrected or not the time differences would still be the same. That's not really the point of this thread. The point is for people at different tracks on different days.

I agree on creating an equal playing field if you want to compare on who's car is faster or who is the better driver. Dynos are SAE corrected so everyone can compare curves equally without outside factors giving one car better results than the other.
 

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Finally, someone understands ...
 

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Discussion Starter #14
I understand that you are implying that this is an estimation and has limited applications. I am in fact 'playing' with this tool - I simply wanted to bring up this topic for those who had always said "I wonder how my times would be at X track instead of up here". Im sure the elite tuners out there have ways to take accurate measuerments of conditions and know how to tweak their own tuning package to adjust. Im not trying to make these calculations serve anything more than they are. Not everyone is a serious tuner, and this topic might get people to start thinking about the conditions they race in and lead them to a greater curiosity and understanding.

P.S. Paul, Im pretty sure the temp was at least 85 deg and maybe even 90.
 

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I know, I know I just like arguing! I see what you mean and again I'm really not trying to knock it, I just didn't want to think of someone being like " oh I would have had such a better time if the weather, if the temperature, if, if " you know what I mean? Anway I will stop arguing now, and go get some slips(with out any formulas) and kill your times!!!
 

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That's cool
Polux, I figured as much ... you stinkin arguers (he,he,he)
...

'So, you wanna be my HuckleBerry ... Come on Johhy! ... What's wrong Johhny?!?! ...' - Doc Holiday (OF COURSE)

Well there you go Pollux, my response for ya as quoted above ... You best to get steppin and bring in these killer time slips of yours. (Smile)


Just remember that you've got to beat my 15.68 1/4 mile and my .505 reaction time.
 

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Discussion Starter #17
BTW Pollux, good luck beating my times - even if you go turbo. You'll probably have to turn up the boost above 5 or 6 psi even then on a GReddy turbo. I wonder what the effective psi boost is that Im running - you wouldnt believe the wide powerband I have - like 2500 to 6500, thats why the 4 speed auto's long gears dont kill me when Im on boost.... I wonder how much 'boost' a 60 shot of nitrous is... I just keep running into these interesting little questions...
 

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Adam - 'simma down now' with all that smack talking
... because you know you need to work on your r/t.
Oh wait, never mind, I forgot you have ana u t o m a t i c (he,he,he)

Ah, you know I'm just messing around.
 

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Discussion Starter #19
Dont forget Paul, my slow little automatic showed you its flashers! Even with you getting the hole shot on me! Just playin dude, you - uh,um took care of me the next run!
 

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I tried to hit you up on chat Adam ... but anyway, man I'm over here LMAO after your last comment!!!
 
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