Originally Posted by Znod' post='255347' date='Mar 15 2006, 05:59 PM

Hi g-man:

We are just leaving the house, and I just now saw your great results. Below is your density altitude. Did you want me to do more than work with your 1/4 results. If so, then I won't be able to do so possibly until tomorrow. And, if so, how did you want be to go about it--using my regression values or the tables?

Your results:
Air Temp 40 (?F)
Altimeter Setting 29.8 (in)
Dew Point 18 (?F)
Altitude 400 (Feet)
Density Altitude -591 (feet)

Here are your basic data corrected to sea level.

Your results:
Density Altitude -591 (feet)
Uncorrected ET 13.35 (sec)
Uncorrected MPH 104.65 (mph)
Corrected ET 13.433
Corrected MPH 103.985

Here they are corrected to 500'.

Your results:
E.T. 13.433 (sec)
Trap Speed 103.985 (mph)
Measured DA 0 (feet)
Corrected to 500(feet) DA
Corrected ET 13.504 (sec)
Corrected Trap Speed 103.429 (mph)

And, below your results are corrected to 1000'. See question 1,000' related question below. I raised it on the other thread too so you obviously can ignore it there.

Your results:
E.T. 13.433 (sec)
Trap Speed 103.985 (mph)
Measured DA 0 (feet)
Corrected to 1000(feet) DA
Corrected ET 13.576 (sec)
Corrected Trap Speed 102.879 (mph)

I think your data look very good no matter where they are corrected to--always better than the mags.

I am wondering if it would be better to present our weather adjusted data at 1,000' feet rather than 500' feet. I am thinking that maybe we should use an altitude that would be "unquestionably" higher than the altitude any magazine would ever be tempted to test at. Another reason for doing so is that it turns out that 1,000' is the average of out altitudes. So, we would be adjusting toward each other. I am pretty sold on this idea. What do you think? I am sure that all of my sub 5 second 0 to 60's would go away, but, regardless, we virtually always would be presenting more conservative data than the magazines.

Originally Posted by grogan545' post='255428' date='Mar 15 2006, 10:14 PM

Can you use your regression values to give a corrected 0-60 time with the info I gave you?I didn't record the other "time to speed" info for this run but I can get it if you need it.

I was at my dealer today and was looking at a 550I step they had in stock,Silver grey.It was loaded and priced out at over $66000.I was tempted but I am not ready yet.I still love my 545.

Originally Posted by Znod' post='255472' date='Mar 16 2006, 12:53 AM

Using my regressions, I get 5.0282. But, be aware that we really don't know how well my regression coefficients will work on your car/data. I also obtained the following using SMOKEmUP:

Your results:
Density Altitude -591 (feet)
Uncorrected ET 4.90 (sec)
Uncorrected MPH (mph)
Corrected ET 4.93
Corrected MPH 0

I am out of time now, but I'll think more about which of these values appears to be more reasonable tomorrow morning. Sorry I am out of time now. I am getting dirty looks. And, why would you want a slower car with a troublesome tranny?

Originally Posted by Znod' post='255472' date='Mar 16 2006, 12:53 AM

Using my regressions, I get 5.0282. But, be aware that we really don't know how well my regression coefficients will work on your car/data. I also obtained the following using SMOKEmUP:

Your results:
Density Altitude -591 (feet)
Uncorrected ET 4.90 (sec)
Uncorrected MPH (mph)
Corrected ET 4.93
Corrected MPH 0

I am out of time now, but I'll think more about which of these values appears to be more reasonable tomorrow morning. Sorry I am out of time now. I am getting dirty looks. And, why would you want a slower car with a troublesome tranny?

Originally Posted by Znod' post='255578' date='Mar 16 2006, 07:55 AM

Hi g-man:

Here is what I was thinking last night. I was pretty sure that I was right, but wanted to confirm.

1. I took the average of my above average 1/4 times and 0 to 60's (N =18). I did the same thing for my 15 below average 1/4 times and 0 to 60's.

2. I found that 100% of the difference in the 1/4 averages was reflected virtually exactly in the difference between the 0 to 60 averages.

3. Then, I used this knowledge to verify the quality of my 0 to 60's based on my regressions.

4. So, I took the average of my 33 unadjusted 1/4 times and 0 to 60's. This time I did the same thing for my 33 adjusted for weather and to 500' 1/4 times and 0 to 60's. My finding was exactly the same as found in 2--100% of the difference in the 1/4 averages was reflected virtually exactly in the difference between the 0 to 60 averages.

So now I have two sources that say my regressions are right on for my car--what's above and their unbelievably good r-squareds and Pearson correlations of 0.9231 and 0.9608, respectively.

Next, I did the same sort of analyis on your latest test.

a. 13.504 (adjusted) - 13.35 (unadjusted) = .154

b. Regression 0 to 60 difference = 5.0282 (adjusted) - 4.90 (unadjusted) = .128, or .128 / .154 = 83.1% of the result of a.

c. Table 0 to 60 difference = 4.93 (adjusted) - 4.90 (unadjusted) = .03, or .03 / .154 = 19.5%

What a, b, and c say to me is that the tables provide a terrible measure of your adjusted 0 to 60 time. They also tell me that regression provides a very good measure of this value--even though the regression coefficients were not develop for your car/data.

However, an even better measure of your 0 to 60 simiply might be 4.90 + .154 = 5.054. A very reasonable range for this value appears to be 5.022 to 5.045 with the values closer to 5.045 seeming more likely to be correct.

Originally Posted by grogan545' post='255721' date='Mar 16 2006, 01:19 PM

Hi Zman.Thank you for your in depth analysis of my numbers.I agree your regression data makes a lot more sense than the tables.Also my "donkey " method seems to be better than the tables.I know there is no real basis for my method ,but it appears to give reasonable data.I checked my old runs for a 1/4 et of close to 13.504(your adjusted of my latest).I had a full unadjusted 1/4 run of 13.50 with a 0-60 time 0f 5.10.My 60' time was only 2.05 sec which I am sure hurt my 0-60 time.My 60' time for yesterdays run was 1.93 sec which I believe would account for the better adjusted 0-60 time(5.045) vs my 5.10.I still need to prove wether my new method of controls on in D is better than no controls.I have to wait for mid may weather to compare to last years times.I am especially interested in the 60' times.With controls off I never had a 60' time under 2.00 sec.I now can do this repeatedly.I don't think it is all because of favorable weather conditions.I think weather conditions affect horsepower which shows up more in the "time to speed"and speed at the 1/8 and 1/4 marks.The 60' time is much more depended on starting method and traction.My traction in cold weather is not good so my reasoning tells me that the starting method I am using now is superior to "controls off" method.

Originally Posted by Znod' post='255827' date='Mar 16 2006, 04:13 PM

You are very welcome g-man. With my other meter, as you may recall, I had many 60' foot times below 2.0, but I can't get them any more. I continue to believe that, while my GT2, is within spec,, it was measuring my times to lower speeds and distances too fast and my times to higher speeds and distances too slow. Also, I think it was measuring my 1/8 speeds to be too slow. I am going to try to arrange a late-date exchange for my GT2. As it is, I it seems useless to me.

I have gone back through all my data and have made everything as conservative as possible (mainly away chose the most conservative justifiable weather data). I eliminated one very small systematic error, a few small recording errors, and a few very small table errors--for all 33 of my passes. Also, I finally have gotten all my data recorded for my regressions--so my regression coeifficients have changed slightly--as they are bound to do over time.

The result is that my "bests" have changed a bit. They now are more comparable to your new pass. The most interesting effect is that my sub 5's now are 5's plus very small amounts--and closer to your new
0 to 60 of 5.045 (????). I will be reposting all of my data given the changes. As mentioned, I think they will look a great deal like your latest--which they should. I think we have the comparability kinks out.

Please let me know if there is anything you want me to eliminate from post #1 of the straight-line thread. What I would like to do is to eliminate all of your old data and add your new pass as your best to date--both adjusted and unadjusted. Basically, your new pass is better than the other two and does not involve use of the formula.

Originally Posted by grogan545' post='256383' date='Mar 17 2006, 01:17 PM

Hi Zman.Your GT2 did always seem to give good numbers off the line and slower numbers as the speed increased.Seems to be a linearity problem.I am satisfied with my accuracy based on the comparison to the drag strip comparison I made last July.I will check it again when I go to the strip.

The 0-60 of 5.045 I got from your post #343(probably most correct).

Go ahead and eliminate all my data from post #1 except my latest run.I think it is a good idea for me to start over.Now that we have been testing for awhile I have a better idea on when and how to conduct my tests.You might want to include my other full 1/4 run of 13.50/105.5 unadjusted.I don't have the weather data for this run so we can't correct it.

I still have a problem getting full 1/4 runs due to factors beyond my control,so I will probably have less data in the future(usually can only make 1 run if I am lucky).

Originally Posted by Znod' post='256392' date='Mar 17 2006, 01:37 PM

Thanks g-man. Right, and the GT2 gave me three 8.71's for the 1/8 and three 5.07's for 0 to 60--both of which are beyond my Pro RR experience. I will update your data for you. I wish you could find a better site. I have you covered on 2/25. Below is what you gave me. Let me know if you want to leave these data posted; they have been posted for quite a while.

2/25/06:

Unadjusted:
1/4 time 13.50
1/4 speed 105.50

(Temp--38F; Dew Point 19F; Pressure?29.98; Altitude?400?; GT2 meter; 1? rollout; D mode; DSC/DTC on; Tries for Minimal Wheelspin)

Adjusted for weather and to 500':
1/4 time 13.704
1/4 speed 103.882

Originally Posted by grogan545' post='256396' date='Mar 17 2006, 01:47 PM

I happen to live in a well populated area.This site would be perfect at 3 am,but impossible because of the deer.No hunting in my area therefore we are grossly overpopulated with deer.They feed constantly at night and are very unpredictable around the roadsides.

You can eliminate that run on 2-25.I forgot that I did give you the weather data.The run was not one of my best.