Q: What's the car length diff between 14 sec 1/4 mile and a 15 sec 1/4 mile?
 

I remember a thread posted here a while back with a formula... I just can't remember it! :(

I'm just curious how big a difference visually 1 second is...
or from 13 to 15 seconds, etc... hence the need for the formula :) hehe

thanks guys :)

Double Post:laugh:

I think it's like, for every .2 seconds, that is 1 car length

Then again, I could be wrong.

At 90-ish trap speeds and these sizes of cars, 1 car-length is equal to about 0.15s. I actually calculated this out, and it's worked out pretty accurately in *cough* street testing *cough* :D

Cars that are hitting 14-flat are up around 100 mph traps though. Then the difference might be more like 0.1s/length or more.

From what I've seen and experienced at the track, assuming both cars have very similar reaction times, the difference between a 15.0 second car and a 14.0 second car is about 4 car lengths. When you start talking about pro-dragsters (5 to 7 second cars), 1 second would be like 180 feet. It's all relative to the acceleration of the car.


Dave

did i double post? damnit... hopefully a mod deleted it :)
or i'll just find it and remove it...

Thanks for the responses. I actually never realised how such a small fraction of a second can actually make a big difference. very cool. :)

Heres a quick ballpark estimate of the number of car lengths the would be present between two 5th Gen Maximas (vehicle length of 191.5 inches or 15.96 ft.)

Of course, the distance between the two cars will be most dependent on the trap speeds of the cars.

Trap Speed / ET Difference / Number of Cars Difference
80 mph / 0.1 sec / 0.74
80 mph / 0.5 sec / 3.68
80 mph / 1.0 sec / 7.35
90 mph / 0.1 sec / 0.83
90 mph / 0.5 sec / 4.14
90 mph / 1.0 sec / 8.27
100 mph / 0.1 sec / 0.92
100 mph / 0.5 sec / 4.60
100 mph / 1.0 sec / 9.19
110 mph / 0.1 sec / 1.01
110 mph / 0.5 sec / 5.05
110 mph / 1.0 sec / 10.11

I was just about to say 10 cars, but the guy above beat me to it. Example. I raced my friend's ITR, we had RTs within a few hundredths of eachother. He ran a 14.33 @ 98 to my 14.6 @ 95 (back in the day) and he was about exactly 3 cars ahead of me. so at 95-100mph trap speeds, 1 car is about .1 seconds difference.

This is not totally accurate in a drag racing environment, but it is easy to calculate the amount of distance travelled at a set speed in a short period of time (and therefore the number of carlengths). You could truly caulcate it based also upon the slower speed of the second vehicle, but the difference would be negligable.

example;

1) mph
90

2) feet per measured mile
5280

3) (1)*(2) = travelled feet per hour
475200.0

4) (3)/60 = travelled feet per minute
7920.0

5) (4)/60 = travelled feet per second
132.0

6) et diff
1.0

7) (5)*(6) = dist travelled during et diff
132.0

8) length of car
15.96

9) (7)/(8) = carlengths travelled during et diff
8.3



ET Difference
000 0.20 0.40 0.60 0.80 1.00
Speed
070 1.29 2.57 3.86 5.15 6.43
072 1.32 2.65 3.97 5.29 6.62
074 1.36 2.72 4.08 5.44 6.80
076 1.40 2.79 4.19 5.59 6.98
078 1.43 2.87 4.30 5.73 7.17
080 1.47 2.94 4.41 5.88 7.35
082 1.51 3.01 4.52 6.03 7.54
084 1.54 3.09 4.63 6.18 7.72
086 1.58 3.16 4.74 6.32 7.90
088 1.62 3.23 4.85 6.47 8.09
090 1.65 3.31 4.96 6.62 8.27
092 1.69 3.38 5.07 6.76 8.45
094 1.73 3.46 5.18 6.91 8.64
096 1.76 3.53 5.29 7.06 8.82
098 1.80 3.60 5.40 7.20 9.01
100 1.84 3.68 5.51 7.35 9.19
102 1.87 3.75 5.62 7.50 9.37
104 1.91 3.82 5.73 7.65 9.56
106 1.95 3.90 5.84 7.79 9.74
108 1.98 3.97 5.95 7.94 9.92
110 2.02 4.04 6.07 8.09 10.11
112 2.06 4.12 6.18 8.23 10.29
114 2.10 4.19 6.29 8.38 10.48
116 2.13 4.26 6.40 8.53 10.66
118 2.17 4.34 6.51 8.68 10.84
120 2.21 4.41 6.62 8.82 11.03