The Official G-Meter Testing Thread
#321
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Originally Posted by grogan545' post='253201' date='Mar 11 2006, 06:33 AM
Somewhere in the smokemup forum there is discussion on the accuracy of these correction factors.They seem to be saying that although they might not be perfectly accurate they are a good way to evaluate changes made to your car.
I like your idea of using 500' altitude as a base.It is probably a lot closer to real world than sea level.The weather here has become unexpectedly warm.I hope to make some runs on monday.The temp is supposed to be about 60-70 F.I'll log the conditions and ask you to correct to 500' altitude.
I thought about where to apply these correction factors.I think it is valid to apply them to all of the "time to distance"points but not to "time to speed" points.
I like your idea of using 500' altitude as a base.It is probably a lot closer to real world than sea level.The weather here has become unexpectedly warm.I hope to make some runs on monday.The temp is supposed to be about 60-70 F.I'll log the conditions and ask you to correct to 500' altitude.
I thought about where to apply these correction factors.I think it is valid to apply them to all of the "time to distance"points but not to "time to speed" points.
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Gents, an interesting post from the M5Board.....
http://www.m5board.com/vbulletin/showthread.php?t=68993
http://www.m5board.com/vbulletin/showthread.php?t=68993
#323
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Originally Posted by Bokke' post='253270' date='Mar 11 2006, 11:39 AM
Gents, an interesting post from the M5Board.....
http://www.m5board.com/vbulletin/showthread.php?t=68993
http://www.m5board.com/vbulletin/showthread.php?t=68993
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Originally Posted by Znod' post='253210' date='Mar 11 2006, 08:08 AM
I think I have a method for determining whether the correction factors apply to all times to distance. I'll get back to you. Good luck with your passes. May they all be sub 5.
Note what I said above, and here goes:
Attempt to Calculate Time to Speed Adjusted to 500'--1/8 Speed:
.................................................. .................................................. ..........Avg
Regression....................83.500...83.276...83 .275...83.106...82.987...83.229
Two Calculators.............83.463...83.522...83.390.. .83.598...83.244...83.443
One Calculator-NHRA.....83.431...83.489...83.357...83.547...83.22 8...83.410
Note that my regression approach explains about 58% of the variability in my raw 1/8 speeds. Thus, I am confident that the regression approach works within highly tolerable error limits. But, note that both the two-calculators and calculator-NHRA approaches yield values that are not too far from those produced by the regression approach. In this regard, I had trouble getting essentially the same values under the former two approaches. I think that error somehow occur when moving to the NHRA table. On average, the two-calculators approach is different from the regression approach by .256462%, while the one-calculator/NHRA approach is different by .217%. I think that reducing 1/8 speeds obtained using the one-calculator-NHRA approach by about .22% is likely to yield good estimates.
Note that my regression approach explains, incredibly, about 92% of the variability in my raw 0 to 60 times. So, 0 to 60 estimates made using this approach are virtually guaranteed to be highly accurate. If you want, I will do an analysis similar to what I did on 1/8 speeds to see what % might be applicable in adjusting 0 to 60 values obtained using the one-calculator-NHRA approach.
Attempt to Calculate Time to Distance Adjusted to 500'--1/8 Time:
.................................................. .................................................. Avg
Regression....................8.756...8.700...8.75 0...8.732...8.763...8.740
Two Calculators.............8.768...8.760...8.804...8. 740...8.801...8.775
One Calculator-NHRA.....8.772...8.762...8.801...8.745...8.803...8 .777
grogan545's formula......8.846...8.750...8.821...8.781...8.816 ...8.803
Similar to the case of my 0 to 60 times, my regresson approach incredibly explains about 96% of the variability in my raw 1/8 times. So, as above, 1/8 time estimates made using this approach are virtually guaranteed to be highly accurate. In this case, I was able to calculate essentially the same values under both of the other approaches. In this case, each method yields results on average that are about .4% higher than those of the regression approach. Here, I think that reducing 1/8 times obtained using either approach by about .4% is likely to yield good estimates. I had hoped that grogan545's formula would have done better, but the above data probably reflect conditions that were not present in the data used in developing the formula.
Happy reading and thinking. Please let me know what you think, of course.
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Originally Posted by cobradav' post='237267' date='Feb 9 2006, 08:30 AM
I have assumed everyone went in both directions to try to take out road level and wind. That is what I intend to do. I have only just now begun to think where I can do this without too much traffic, population and availablility. Looks like I have to go about 10-15 miles from home to get to a decent place. I could get closer but would have to be after dark.
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Originally Posted by wolverine' post='253524' date='Mar 11 2006, 09:39 PM
I may have already weighed in on this, but you are absolutely right. You MUST do runs in both directions, unless you are on a dragstrip. You just cannont 'eyeball' a level road. I've been doing timed runs on the same 'absolutely flat' section of road for 12 years, and one direction is consistently a few tenths quicker every time.
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Originally Posted by Znod' post='253485' date='Mar 11 2006, 07:20 PM
Addendum to post #324:
Attempt to Calculate Time to Distance Adjusted to 500'--1/8 Time:
.................................................. .................................................. Avg
Regression....................8.756...8.700...8.75 0...8.732...8.763...8.740
Two Calculators.............8.768...8.760...8.804...8. 740...8.801...8.775
One Calculator-NHRA.....8.772...8.762...8.801...8.745...8.803...8 .777
grogan545's formula......8.846...8.750...8.821...8.781...8.816 ...8.803
I had hoped that grogan545's formula would have done better, but the above data probably reflect conditions that were not present in the data used in developing the formula.
Attempt to Calculate Time to Distance Adjusted to 500'--1/8 Time:
.................................................. .................................................. Avg
Regression....................8.756...8.700...8.75 0...8.732...8.763...8.740
Two Calculators.............8.768...8.760...8.804...8. 740...8.801...8.775
One Calculator-NHRA.....8.772...8.762...8.801...8.745...8.803...8 .777
grogan545's formula......8.846...8.750...8.821...8.781...8.816 ...8.803
I had hoped that grogan545's formula would have done better, but the above data probably reflect conditions that were not present in the data used in developing the formula.
1/4 Mile Time (given)..............13.70.....13.70........13.70
1/4 Mile Speed (given)..........102.00....104.00.....103.00
1/8 Mile Speed (estimated).....81.00......81.00.......81.00
1/8 Mile Time (predicted)...........8.89.......8.95.........8.92
So, no wonder the forumula does not work too well above.
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Originally Posted by Znod' post='253692' date='Mar 12 2006, 10:24 AM
I had never noticed the following with respest to the formula. If the 1/4 mile speed is very high in relation to 1/8 mile speed (estimated) then, of course, 1/8 mile time (predicted) will suffer. I notice this "feature" of the formula when trying to estimate 1/8 times for the mags. So, for example, not using the actual mag times:
1/4 Mile Time (given)..............13.70.....13.70........13.70
1/4 Mile Speed (given)..........102.00....104.00.....103.00
1/8 Mile Speed (estimated).....81.00......81.00.......81.00
1/8 Mile Time (predicted)...........8.89.......8.95.........8.92
So, no wonder the forumula does not work too well above.
1/4 Mile Time (given)..............13.70.....13.70........13.70
1/4 Mile Speed (given)..........102.00....104.00.....103.00
1/8 Mile Speed (estimated).....81.00......81.00.......81.00
1/8 Mile Time (predicted)...........8.89.......8.95.........8.92
So, no wonder the forumula does not work too well above.
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Originally Posted by grogan545' post='253887' date='Mar 12 2006, 04:33 PM
Still digesting your last several posts Zman.I will get back to you latter this evening or tomrrow.Weather here is not cooperating(rain)for testing.Hopefully tomorrow will be better.
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Originally Posted by Znod' post='253485' date='Mar 11 2006, 07:20 PM
Hi g-man:
Note what I said above, and here goes:
Attempt to Calculate Time to Speed Adjusted to 500'--1/8 Speed:
.................................................. .................................................. ..........Avg
Regression....................83.500...83.276...83 .275...83.106...82.987...83.229
Two Calculators.............83.463...83.522...83.390.. .83.598...83.244...83.443
One Calculator-NHRA.....83.431...83.489...83.357...83.547...83.22 8...83.410
Note that my regression approach explains about 58% of the variability in my raw 1/8 speeds. Thus, I am confident that the regression approach works within highly tolerable error limits. But, note that both the two-calculators and calculator-NHRA approaches yield values that are not too far from those produced by the regression approach. In this regard, I had trouble getting essentially the same values under the former two approaches. I think that error somehow occur when moving to the NHRA table. On average, the two-calculators approach is different from the regression approach by .256462%, while the one-calculator/NHRA approach is different by .217%. I think that reducing 1/8 speeds obtained using the one-calculator-NHRA approach by about .22% is likely to yield good estimates.
Note that my regression approach explains, incredibly, about 92% of the variability in my raw 0 to 60 times. So, 0 to 60 estimates made using this approach are virtually guaranteed to be highly accurate. If you want, I will do an analysis similar to what I did on 1/8 speeds to see what % might be applicable in adjusting 0 to 60 values obtained using the one-calculator-NHRA approach.
Attempt to Calculate Time to Distance Adjusted to 500'--1/8 Time:
.................................................. .................................................. Avg
Regression....................8.756...8.700...8.75 0...8.732...8.763...8.740
Two Calculators.............8.768...8.760...8.804...8. 740...8.801...8.775
One Calculator-NHRA.....8.772...8.762...8.801...8.745...8.803...8 .777
grogan545's formula......8.846...8.750...8.821...8.781...8.816 ...8.803
Similar to the case of my 0 to 60 times, my regresson approach incredibly explains about 96% of the variability in my raw 1/8 times. So, as above, 1/8 time estimates made using this approach are virtually guaranteed to be highly accurate. In this case, I was able to calculate essentially the same values under both of the other approaches. In this case, each method yields results on average that are about .4% higher than those of the regression approach. Here, I think that reducing 1/8 times obtained using either approach by about .4% is likely to yield good estimates. I had hoped that grogan545's formula would have done better, but the above data probably reflect conditions that were not present in the data used in developing the formula.
Happy reading and thinking. Please let me know what you think, of course.
Note what I said above, and here goes:
Attempt to Calculate Time to Speed Adjusted to 500'--1/8 Speed:
.................................................. .................................................. ..........Avg
Regression....................83.500...83.276...83 .275...83.106...82.987...83.229
Two Calculators.............83.463...83.522...83.390.. .83.598...83.244...83.443
One Calculator-NHRA.....83.431...83.489...83.357...83.547...83.22 8...83.410
Note that my regression approach explains about 58% of the variability in my raw 1/8 speeds. Thus, I am confident that the regression approach works within highly tolerable error limits. But, note that both the two-calculators and calculator-NHRA approaches yield values that are not too far from those produced by the regression approach. In this regard, I had trouble getting essentially the same values under the former two approaches. I think that error somehow occur when moving to the NHRA table. On average, the two-calculators approach is different from the regression approach by .256462%, while the one-calculator/NHRA approach is different by .217%. I think that reducing 1/8 speeds obtained using the one-calculator-NHRA approach by about .22% is likely to yield good estimates.
Note that my regression approach explains, incredibly, about 92% of the variability in my raw 0 to 60 times. So, 0 to 60 estimates made using this approach are virtually guaranteed to be highly accurate. If you want, I will do an analysis similar to what I did on 1/8 speeds to see what % might be applicable in adjusting 0 to 60 values obtained using the one-calculator-NHRA approach.
Attempt to Calculate Time to Distance Adjusted to 500'--1/8 Time:
.................................................. .................................................. Avg
Regression....................8.756...8.700...8.75 0...8.732...8.763...8.740
Two Calculators.............8.768...8.760...8.804...8. 740...8.801...8.775
One Calculator-NHRA.....8.772...8.762...8.801...8.745...8.803...8 .777
grogan545's formula......8.846...8.750...8.821...8.781...8.816 ...8.803
Similar to the case of my 0 to 60 times, my regresson approach incredibly explains about 96% of the variability in my raw 1/8 times. So, as above, 1/8 time estimates made using this approach are virtually guaranteed to be highly accurate. In this case, I was able to calculate essentially the same values under both of the other approaches. In this case, each method yields results on average that are about .4% higher than those of the regression approach. Here, I think that reducing 1/8 times obtained using either approach by about .4% is likely to yield good estimates. I had hoped that grogan545's formula would have done better, but the above data probably reflect conditions that were not present in the data used in developing the formula.
Happy reading and thinking. Please let me know what you think, of course.