Old Drag Racer Formulas: The "Q" Ratio or Factor??

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12many

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Any old timers or old school racers remember something refered to as the Q" factor (or ratio) ?? Not sure if thats what its exactly called, I think you multiply your ET and MPH and you compare that figure to 1320, and how close or far (below/above) you are tells you about your setup? I believe I read about it on Grumpys Garage site but can't find anything anywhere about it, been a while
 
12many said:
Any old timers or old school racers remember something refered to as the Q" factor (or ratio) ?? Not sure if thats what its exactly called, I think you multiply your ET and MPH and you compare that figure to 1320, and how close or far (below/above) you are tells you about your setup? I believe I read about it on Grumpys Garage site but can't find anything anywhere about it, been a while
Click to expand...
The one I use often to generally compare overall power vs efficiency-
1320 divided by 1/4mi mph = 1/4mi et potential
A well sorted car can generally come within a couple tenths of the formula.

Grant
 
440outlawdart said:
would that apply to 1/8 mile
Click to expand...

You can substitute 660 for 1320, but it's pretty hard to find a car that can match the 660 formula. Still a useful way to compare cars though.

I laugh when I see someone bragging about a car running big mph for the et. To me, it just means the car isn't performing to it's potential.

Grant
 
weedburner said:
The one I use often to generally compare overall power vs efficiency-
1320 divided by 1/4mi mph = 1/4mi et potential
A well sorted car can generally come within a couple tenths of the formula.

Grant
Click to expand...
That's the one, thanks for clarifying it for me:thumbsup:
 
Use that one a lot, just wanted things cleared up on this old pen and paper style calculation :)
 
Here's a series of 1/8mi timeslips from last weekend, one of my stickshift customers running a 4spd manual trans with a diaphragm clutch controlled by one of my ClutchTamers…

charliebooze112018.jpg

He's within a tenth of the 660 formula on the first two slips, a little over a tenth above the 660 formula on the second two slips. On 1/4mi passes he's usually pretty close or even beats the 1320 formula.

Grant
 
On my last outing using (#50 on slips) the 660 it obviously won't compute! But it is sort of a refernce point nonetheless. On the 1320, my first run is basically spot on, and my second run of I beat it. Both 60' are off from my bests of 1.68/1.69 which were achieved from dead hook days vs. the cool temps I just ran in. And I'm still off on ideal 60' times based on various formulas as applied to all the runs I've made (How To Hook And Launch book, for one reference) its back and forth from one thing to another!

IMG_20181110_201808.jpg
 
It seems accurate,I figure I could pick up 1/2 sec with a serious tire. I run 11.83 at 116.55 on the little tire. Calculator calls for 11.32
 
Here's one I used to use from days gone by....
If you made a pass that was compromised in some way (spun the tires, or lost fuel pressure at the 1000' mark, etc.)
take 1320 and divide your ET to get MPH, OR divide MPH to get your ET.
example: 1320/108 = 12.22 (ET) , or 1320/12.22= 108 (MPH) its real accurate in the 12 sec range, but it's not as accurate for faster cars.. fun to play with, easy to remember.
 
ET/MPH From Horsepower Calculators

Used this when I was racing a long time ago, accurate for my cars and others I have tried and know about, will show numbers for a reasonably good leaving car, mph can be slightly over by 1mph. Won't work well for any S/SS type leaving car. You can also work out your fwhp from your weight by changing the hp numbers till you get the same as your slip mph. The Moroso wheel will show less hp.
 
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