Converting 60ft times to 060 MPH times 
02092002, 08:01 PM

#1  TECH Fanatic Thread Starter
Join Date: Nov 2001 Location: Freeland, MD
Posts: 1,347
 Converting 60ft times to 060 MPH times I frequently get asked what our cars 060 times are (the nondrag racing crowd). Last night, I did a few of the equations and posted (on the other site) what I thought the 60ft MPH would be based on the times. Does this look right? Did I miss anything?
BTW  this is the kind of stuff you do when you are out of commission (from recent surgery), and everyone else is out racing <img src="gr_sad.gif" border="0">
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060 is a function of traction, engine power, rear end gearing, (if M6) shifting ability, and (if A4) torque converter choice.
You can kind of back out a 060 from a 60 ft time. For example, if you assume a constant acceleration over the 60 ft time (which is not always a good assumption), then you can assume that your time to distance function is given by the double integral of a constant acceleration:
0.5 * acceleration*(60ft time)^2 = 60 ft
Solving this gives acceleration in ft / sec^2 of
a = 120 ft / (60ft time)^2
Since 1 MPH is about 1.47 ft/sec, assuming the constant acceleration, noting velocity is acceleration times time, and solving for the math,
Velocity at end of 60 ft is approximately 81.82 / 60fttime (units ignored for simplicity).
In other words, take your 60 ft time, divide it into 81.82, and that will give you an approximate MPH at the end of the 60 ft.
Here are a few values
2.0 60 ft  end velocity is 40.9 MPH
1.8 60 ft  end velocity is 45.5 MPH
1.6 60 ft  end velocity is 51.1 MPH
1.5 60 ft  end velocity is 54.5 MPH
1.4 60 ft  end velocity is 58.4 MPH (very quick 060 <img src="gr_eek2.gif" border="0"> )
1.3 60 ft  end velocity is 62.9 MPH
1.2 60 ft  end velocity is 68.2 MPH
The above values are not going to be right due to the approximations used, but are close. And this is why drag racing is frequently won/lost in the 60 ft time. Incidentally, 1 g of (average) acceleration is somewhere around the 1.9 sec 60 ft time. 1 g of average acceleration over a whole 1/4 mile gives you a 9.08 ET. Cars do not have a constant acceleration over a 1/4, however, which is why that is way off. 
 
02092002, 10:04 PM

#2  Moderator
Join Date: Nov 2001 Location: ChiTown
Posts: 3,029
 Re: Converting 60ft times to 060 MPH times so if my 60' is 1.55, i can say my 053mph is ~1.55 seconds <img src="gr_eek2.gif" border="0">
making my 060 around 2 seconds <img src="gr_eek2.gif" border="0">
if so, thats freaking incredible! 
 
02142002, 11:10 AM

#3  Launching!
Join Date: Nov 2001 Location: Minneapolis, MN
Posts: 260
 Re: Converting 60ft times to 060 MPH times well according to Al Corda's car page, his car has a 1.28 60' time which says 060 in 1.9 seconds. 
 
02142002, 05:45 PM

#4  D(irecto)r Pepper
Join Date: Nov 2001 Location: Houston Raceway Park...in TEXAS.
Posts: 1,952
 Re: Converting 60ft times to 060 MPH times [quote]Originally posted by Red02LS1:
<strong>well according to Al Corda's car page, his car has a 1.28 60' </strong><hr></blockquote>
Oh man... 1.2!!! KILLER!
1.2, 1.2, 1.2.... I feel like "jim Cary" in "Dumb and Dumber" when I say, "So, it CAN be done...."
I can only dream. 
 
02142002, 07:40 PM

#5  TECH Fanatic Thread Starter
Join Date: Nov 2001 Location: Freeland, MD
Posts: 1,347
 Re: Converting 60ft times to 060 MPH times [quote]Originally posted by Bad Habit Bird:
<strong>Im not sure those numbers are totally correct. The colonel posted a link to a site that had a calculator that would do this conversion, maybe he will post the link again.</strong><hr></blockquote>
They may not be right  see the other post at https://ls1tech.com/ubb/cgibin/ulti...c&f=5&t=000676
I was stabbing in the dark at this. The big problem is what does the acceleration curve look like for that first 2 seconds. Changes a lot of things. 
 
02142002, 10:55 PM

#6  Launching!
Join Date: Jan 2002 Location: Plymouth,MA
Posts: 254
 Re: Converting 60ft times to 060 MPH times 
 
02152002, 12:09 AM

#7  TECH Fanatic Thread Starter
Join Date: Nov 2001 Location: Freeland, MD
Posts: 1,347
 Re: Converting 60ft times to 060 MPH times Much of how you calculate this depends upon your assumption of what the acceleration curve looks like during that 60 foot. Thinking about this a little more, I suspect that the above calculations are probably going to be a bit more accurate for a 6speed than a highstall auto because of the shape of the torque converter spike.
In actuality, there is no one formula that is going to be exactly right because every car's power curve and effective gearing are going to be different. Moreover, you cannot always even get very good 1/4 MPH or ET estimates from a car's peak power. For example, the calculations available at http://www.prestage.com/carmath/calc_ETMPH.asp
seem to be way off (much too slow) for LS1powered applications. I am sure that this has to do with the width and placement of the power curve, which does not always compare well across vehicle types.
I *think* that what I have above is probably going to get realistically close to backing out this number (unless someone has really done their homework on this for LS1s and F/Y bodies and has a better solution). It also helps to keep in mind that this a tool to let the nongearhead crowd have some idea on how fast our cars are. No one in drag racing cares that much about 060. 
 
02152002, 12:12 AM

#8  TECH Fanatic Thread Starter
Join Date: Nov 2001 Location: Freeland, MD
Posts: 1,347
 Re: Converting 60ft times to 060 MPH times [quote]Originally posted by Vortech396:
<strong>I think this is the one Colonel posted a while back. http://www.smokemup.com/utilities/calc/60_foot.cfm
have fun <img src="gr_grin.gif" border="0">
John</strong><hr></blockquote>
Wow  it's giving the same answers that I posted above. Interesting. 
 
02152002, 12:38 AM

#9  TECH Fanatic
Join Date: Nov 2001 Location: The Woodlands, TX
Posts: 1,934
 Re: Converting 60ft times to 060 MPH times Im not sure those numbers are totally correct. The colonel posted a link to a site that had a calculator that would do this conversion, maybe he will post the link again. 
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