1/8 to 1/4 mile conversion formula? - Chevelle Tech
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post #1 of 11 (permalink) Old Apr 19th, 00, 11:37 PM Thread Starter
TH
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I need the formula that allows you to compute an approximate 1/4 mile ET based on a known 1/8 mile time. It's not in the dang Auto Math Handbook!

Thanks much.

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post #2 of 11 (permalink) Old Apr 20th, 00, 6:15 AM
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Here is the chart that I use, which I found in an "Car Craft":

1/8=1/4
4.6=7.08
4.7=7.24
4.8=7.39
4.9=7.55
5.0=7.70
5.1=7.85
5.2=8.00
5.3=8.16
5.4=8.32
5.5=8.47
5.6=8.62
5.7=8.78
5.8=8.93
5.9=9.09
6.0=9.24
6.1=9.39
6.2=9.55
6.3=9.70
6.4=9.86
6.5=10.01
6.6=10.16
6.7=10.32
6.8=10.47
6.9=10.63
7.0=10.78
7.1=10.93
7.2=11.09
7.3=11.24
7.4=11.40
7.5=11.55
7.6=11.70
7.8=12.01
7.9=12.17
8.0=12.32
8.1=12.47
8.2=12.63
8.3=12.78
8.4=12.94
8.5=13.09
8.6=13.24
8.7=13.40
8.8=13.55
8.9=13.71
9.0=13.86
9.1=14.01
9.2=14.17
9.3=14.32
9.4=14.48
9.5=14.63
9.6=14.78
9.7=14.84
9.8=15.09



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Rob Clary
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post #3 of 11 (permalink) Old Apr 20th, 00, 11:45 AM
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Wow, I knew my father-in law's car was fast, but I never thought about 9.40's through the 1/4! Out of the box he ran a 6.19, but hey, it is an aluminum headed 468 B/B in an Opal GT body!

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post #4 of 11 (permalink) Old Apr 20th, 00, 3:39 PM
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Now Doug, you know those 1/8 guys are geared to hell and back. He would have to run through the traps at over 7000RPMS probably

That chart differs some for 60' times.

With my 3.73 posi (motor is a little weak) I got he following

1/8th = ~10.00 sec

1/4th = ~14.5 sec

I know it's at the bottom of the list, but things do very some with a 4,000 pound car and less than 4:11 gears.

my .02

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post #5 of 11 (permalink) Old Apr 20th, 00, 4:47 PM
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Mike- His car weighs right at 1900lbs, and he has a 4.88 or 5.13 under it right now. It is still spinning as he goes through the traps. I haven't volunteered to drive,because, as you know, I'm a pretty good sized guy, and folding myself up to get in that sardine can isn't in my future!

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post #6 of 11 (permalink) Old Apr 20th, 00, 9:57 PM Thread Starter
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Chevy454,
Thanks a lot for the chart. I printed that thing out. Nice reference!


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post #7 of 11 (permalink) Old Feb 27th, 03, 1:41 PM
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We'll see if the image comes through...I put the numbers into an Excel spreadsheet chart. Sort of the 'po mans pocket calculator. The equations are on the chart, too. But they worked out to:

1/4 mi = (1/8 mi) x 1.54

1/8 mi = (1/4 mi) / 1.54

Or very roughly just multiply or divide by 1.5x


Also, looked like the list numbers contained a small error at 1/8mi=9.7 sec. The 1/4 mile should be 14.92 to fit on the line with all the other points...unless the laws of physics somehow break down approaching the 9.7 sec 1/8 mile barrier.

(awww---looks like I'll have to beam the image up later tonight)

Corey<br /><a href="http://www.sunflower.com/~corey872" target="_blank">Corey's 67 Chevelle Page</a>
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post #8 of 11 (permalink) Old Feb 27th, 03, 7:06 PM
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Give this a shot:


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post #9 of 11 (permalink) Old Dec 27th, 03, 4:12 PM
 
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I've been using 1.575....seems to be really close in most cases.

Unknown the world over
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post #10 of 11 (permalink) Old May 28th, 10, 1:38 AM
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Re: 1/8 to 1/4 mile conversion formula?

We run 1/8 mile......got a iroc camero and we have a 342 rearend gear.....Had alittle work done to the motor....we put vortec heads and vortec eldabrock intake....we ran a 9.40.....We are spinning the tires about 20 to 30 feet.....Do you think if we get better tires and stop the spinning.....Do you think we can get into the 8's
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Old Nov 7th, 10, 6:28 AM
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post #11 of 11 (permalink) Old Nov 7th, 10, 10:13 AM
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Re: 1/8 to 1/4 mile conversion formula?

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