grogan545

right Zman

znod

Hi g-man:

I have already worked out my conversions. My adjustment related values look like this:

Density Altitude--1233.2 from densitity altitude calculator 2 (which requires the most inputs)
0.98696667--Times correction factor calculated by me using NHRA table
1.01336667--Speeds correction factor calculated by me using NHRA table.

I feel very comfortable with my factors since they are less favorable than if I had simply used the NHRA corrections for my altitude of 1550. They are less favorable because of good weather factors.

According to my calculations your factors are not favorable--as I expected. To your knowledge can you have correction factors that would yield times/speeds less good than if 1.0 were used? If not, then your values would be unchanged.

But, when I plug your data in, I get the values below.

Density Altitude/-2153.9 (which is calculated by calculator 2)
1.02506473--Times correction factor calculated by me using NHRA table
0.97366245----Speeds correction factor calculated by me using NHRA table.

Of course, if I use these values, then your results will be worse than your raw results. Here is how I calculated the last two using the NHRA table.

2154/2200 = .9790909
The correction for +2200 = 1 - .9744 = .0256.
So, the correction factor would be 1 + .9790909(.0256) = 1.02506473 (assuming it can be greater than 1).

The second correction factor for +2200 = 1.0269 - 1 = .0269.
So, the correction factor would be 1 - .9790909(.0269) = .97366245 (assuming it can be greater than 1).

Please let me know if you agree with my calculations or perhaps that the correction values should not be greater than one. I'd be happier if they can't be greater than one.

grogan545

Yes Zman the correction factors can be in a negative direction.The standard conditions were set by some guru in the past, and weather conditions worse than the standard will yield a factor to increase your speed & decrease your time and weather conditions better than standard will do the opposite.I think if you search that automath site you can find the standard conditions(like 70 F,29.12 bar,?dew point).

I think you took an unecessary step on my factors.For example if I use the following:
1.0250647 X 13.26=13.59 et
.97366245 X 105.5(est)=102.72
Theoreticaly if we make many runs in many different weather conditions we should correct to these figures every time unless ther are mitigating circumstances(poor start,Controls kicking in).In practice I doubt that that the times will be that consistant.

Overall I don't think we will like the correction factors because all aparant loss's & gains due to weather will be muted.But if we want to be scientific it is the only fair way to compare times.

When I apply the factors you generated for my car to the 0-60 times posted on 2-20-06 I get
4.80 X 1.0250647=4.92
4.98 X 1.0250647=5.10
average 5.01 corrected ,still better than an published data.

What are your thoughts Znod?

znod

Right, I took an extra step. But, we agree on the factors right? I think we ought to present both when we present data; one set of data pertiinent in our own locals and the other for comparability between ourselves. For now, I was going to compare your average for your best N and S with my best run. What do you think?

grogan545

Sounds like a winner to me Zman.The only thing I think I need to establish is my actual altitude at my test site.I think I need to subtract it from the "equivilent altitude" from the NHRA table.

znod

Ok, but I am not sure why you would subtract. If you needed to, then I would too. Are you saying that I would need to subtract thusly: 1550 - 1233.2 = 316.8 for some reason. I used 300' for you in the determinaton of density altitude--since you mentioned this approximation before. It seems to me that the use of our actually altitudes would only be needed in this step.

znod

What would your estimate your 0 to 100 time be on your recent great pair of runs?

grogan545

My best estimate for 0-100 mph on my recent great runs as follows:
run 1 11.45
run 2 11.79

Sorry Zman I looked at smokemup again.You used density calculator #2 which asks for the altitude,so not necessary to subtract anything.I did find the altitude of the airport that is 5 miles from my test site.It is 524' so you can plug that in for future calculations for me.

Look under tech articles in smokemup there is very detailed info on weather corrections.Also could you plug my numbers for my 2 great runs into the"1/4 mile corrections to sea level"formula based on the info I gave earlier.Curious if the results are the same as with the equivilent altitude corrections

znod

No problem. I'll use the 534 value now; not too much trouble to change things. Calculators 1 and 2 don't give exactly the same results if you are referring to calculator 1 as the sea-level formula. I used calculator 2 because it required more info. The results of the two are close enough, though, that it should not matter which we use. As I recall Calculator 2 gives more conservative results after subtracting actual altitude. Strangely enough, the results of at least Calculator 2 are different if we measue "Altitude Setting" in milibars hPA versus inches of mercury. I used inches of mercury since the results are a bit more conservative (fortunately that's what you gave me). It is unclear to me if the more conservative calculation somehow "double counts" weather effects, but it shouldn't. Much of what I have said is slightly tentative so don't take everything as gospel. I'll explain more later. Back to the drawing board.

znod

OK, g-man, here we go on the new era of E60 Discussion g-meter performance reporting. I am posting the tables tonight, and if I see any gross errors tomorrow, then I correct and reattach them.

Note that your 1/4 mile results are based on Grogan's fabulous formula since you did not actually compete the 1/4 in either direction of your averaged results. Also, I took the average of runs 1 and 2 above to get your unadjusted zero to 100 value--since you also did not make it to 100 on your runs. And, as you know, I don't average my results because my tests show that my strip is sufficiently level.

For all, the first set of side-by-side tables provides a comparison of what amounts to our best single runs to date--after both of us updated to 20.01.00 and after removal of my mods. These tables provide an indication of how we might do side by side on the same sea-level strip under excellent weather conditions. The second set of side-by-side tables provides the raw data upon which the top two tables are based. They are not particularly good for making comparisons since the elevations and weather conditions under which our runs were conducted are not acceptably comparable (e.g., my elevation is 1,500 feet, while grogan545i's is 534 feet.

I am tired now. I'll clean up any messes I have made tomorrow.