By how many quad lengths ahead should you win a drag race if you are 0.1 seconds faster than your competitor? In other words, if person X drag races over 300ft in 6.1 seconds and X beats person Y who ran the same race at 6.5 seconds, then the result is that X beat Y by 0.4 seconds. So how many quad lengths ahead should X win by if X beat Y by 0.4 seconds? Is the answer 4 quad lengths or something else? [img]i/expressions/face-icon-small-confused.gif[/img]

The reason I ask is because I've been conducting timed runs with my P650 to test the effects of different mods, and I want to know if how many quad lengths difference that each 0.1 second improvement has.

 

You can get a good estimate. First you need and idea of velocity at the end of 300ft. That would be about 90ft/sec at that pace. Multiply that by 0.1. So a good estimate would be 9ft.

 

Green700,
Many thanx for your response. If I follow you correctly, a 0.1 second win equals about 1.5 quad lengths ahead in a 300 ft drag race (based on the fact that P650 is about 6 feet long)...Is this right OR did you mean to say that 0.4 seconds equals a 9 ft lead?

 

Just knowing the time and distance is not enough info unless you assume average acceleration which will not be the case, i.e. the time to go from 10MPH to 20MPH will not equal 20MPH to 30MPH and so on. With average acceleration, you could then ask how far the faster ATV moved in the time it took the slower ATV to reach the finish using (Distance = (Acceleration x Time squared) / 2). Solve this for the faster ATV's acceleration and then plug in the slower ATV's time.

For example given Distance = 300ft, ATV fast time = 6.1, ATV slow time = 6.2, then Acceleration = 2D/T^2 or 16.12ft/s^2 for the fast ATV. Then this ATV in 6.2 seconds will travel (16.12ft/s^2 x (6.2s)^2) / 2 = 309.8ft, or about 10ft more than the slow ATV.

For a close "guess", just take note of the terminal speed at the finish line. If it were about 68MPH or 100ft. per second, you would be close to 10ft ahead in 0.1 seconds. Use (MPH x 5280FT / 3600Secs) then multiply by the time difference in seconds and you get the answer in feet.

Since you probably wouldn't be going 68MPH at the finish line, or put another way, 0 to 68MPH in only 6.1 seconds, this shows how the average acceleration assumption can give you bad results. Your true acceleration will be much higher at first, and then continually go lower.

 

PRAIRIE633... your algebra looks correct... however the shorter the distance i.e. 300 ft compared to1320 ft ( rough 1/4 mile ), the easier or, more accurate the estimates will be... it would be obviously foolish to use those estimates at the 1/4 mile distance, but the acceration curve of most ( normal ) quads will give reasonable results in 300 ft, using GREEN700's formula, for all but the most technical of racers...

 

As a general rule of thumb. 0.1 equal 1 1/2 quad length.

Hard to figure on speed at finish line alone.

example. two quads racing, 300 ft.

slower quads beats faster quad out of hole by three lengths because of wheel spin on faster quad.

Faster quads over takes and passes slower quad just before finish line, and wins by 0.1 sec.

Slower quad might have been going 55 mph at finish line.
faster quad might have been going 60 mph at finish line.

if you took both speeds at the finish line and times them by the feet per sec they were traveling at the end, it would look like the faster quad won by a lot when in fact he won by 0.1 sec.

 

Shotgun,
Thanx for the reply. Did you really mean that 0.01 seconds faster is roughly equal to 1.5 quad lengths ahead? I'm no math wiz, but 0.01 seconds seems like an awefully minute period of time to be ahead by 1.5 quad lengths. Did you mean to say that 0.1 seconds is roughly equal to 1.5 quad lengths ahead?

Thanx again for your response!

 

Sorry,

to busy thinking of what to say. I meant 0.1,

I'll fix it.

 

I used the word "estimate" twice when I said 9ft. Then you go through all this trouble to say your guess is 10ft. Geez. An estimate is an estimate. Niether of us can know the exact distance with the numbers provided.

 

Green700, My post wasn't an answer to yours, by the time I typed and posted it, yours and another was there. Your "estimate" and my "guesstimate" are the same thing, unless you mean to always use 90ft/s? I though he wanted the calculations since he used all of the "X" and "Y" stuff, I guess not.

Newbeetle, I am not sure why the estimate would be foolish for 1/4 mile? If both ATV's top out at 68MPH (just to simplify things) and they cross the line 0.3 seconds apart because one had a Holeshot installed, wouldn't the distance between them simply be the distance covered in 0.3 seconds at 68MPH, or simply 30 feet?

Who can work a stopwatch consistantly to 0.1 seconds of resolution anyway? Wouln't you at least want to use some electronics for this stuff to be accurate?