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Quarter mile time difference = car lengths?

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Old Oct 13, 2005 | 05:55 PM
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Default Quarter mile time difference = car lengths?

Okay, this is a totally idle question that has little to do with anything, but is there any conversion out there to figure out what distance a losing car will be behind in the 1/4 mile based on timeslips?
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Old Oct 13, 2005 | 06:59 PM
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Generally 1 car length is nearly equal to .1 in a quarter mile.
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Old Oct 13, 2005 | 07:52 PM
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sorry but not even close- it is impossible to tell on the street, hell even at the track it is impossible to measure carlengths and come up with some type of ratio of lengths/tenth that works every time. no way, one carlength is not necessarily .1 at all, usually more imho like .3, it depends if somebody is pulling on you, depends who left first (im talking if you left .1 before the other person etc...), there are too many factors.

street racing measurement= carlengths
track racing measurement= 1/4 mile time done by timing equipment.

one of MY pet peves is when somebody looses by say 2 carlengths, then find out my car has gone 12.1 so they automatically assume they have a 12.3 or 12.5 car. i try to explain to them that this is not necessarily the case- some don't believe me till they go to the track and run a 12.1 and call me a liar for sandbagging my times "you must be in the 11's!" they say, or run a 12.8 and call me a liar for telling people my car ran what it did "your **** doesn't run low 12's" they'd say. the street is totally different my friend.
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Old Oct 13, 2005 | 07:55 PM
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Originally Posted by black_knight
Okay, this is a totally idle question that has little to do with anything, but is there any conversion out there to figure out what distance a losing car will be behind in the 1/4 mile based on timeslips?

Here you go, Dear John is right on the $. (assuming a mph)

http://www.final-decision.com/mov.html
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Old Oct 13, 2005 | 09:14 PM
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See, I figure it would take some serious calculus and also a full timeslip...
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Old Oct 14, 2005 | 10:29 AM
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Originally Posted by J 98ta
Here you go, Dear John is right on the $. (assuming a mph)

http://www.final-decision.com/mov.html
Thanks buddy.

I guess there will always be stipulations, but that's what I've always gone by and it hasn't failed me yet.
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Old Oct 14, 2005 | 11:20 AM
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1/10 = 1 car length is a good ball park est.
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Old Oct 14, 2005 | 11:50 AM
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Originally Posted by black_knight
See, I figure it would take some serious calculus and also a full timeslip...
Oops! Missed the link there. I guess someone did the calculus. Sweet.
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Old Oct 14, 2005 | 12:40 PM
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You could lose by a car length and have a quicker time and vice-versa. Depends on your reaction time.
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Old Oct 14, 2005 | 01:22 PM
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Originally Posted by warpwr
You could lose by a car length and have a quicker time and vice-versa. Depends on your reaction time.
Right, but with reaction time being equal 1 car length = .1 or close to it.
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Old Oct 16, 2005 | 01:31 PM
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Also depends on how your car versus the opposite car run the "back-half" of the 1/4 mile. If you car doesn't 60 foot well and the other car does, and you run more mph than he/she does at the finish, the 1 tenth = one car length may not hold up. I agree it is a good estimate, but it falls under the "guess my et based on rwhp" factor. The only way you'll know for sure is to race the car!

Derek
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Old Oct 16, 2005 | 01:41 PM
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after i ran at the track i thought it made street racing look pretty stupid. reaction time can differ from something like .3 seconds and on the street its not even that noticable but it makes a huge difference
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Old Oct 18, 2005 | 04:55 PM
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It all depends on how fast the cars are. A car length between two 140mph cars is a lot different than a car length between two 100mph cars. 140mph is about 205fps and 100mph is roughly 147. Of course, you have to factor in the launch, and the rate the cars are accelerating.

In other words, a win is a win and if you want times, go to the test & tune @ the track.
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Old Oct 22, 2005 | 07:07 PM
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Just calculate from the speed the winning car is going. eg
If its 115mph it is travelling at 51m/s so 0.1s will be 5.1m or 16feet8inches
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Old Oct 22, 2005 | 07:40 PM
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Why guess?
Just take it to track and find out what it really runs
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Old Oct 24, 2005 | 02:36 AM
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Originally Posted by oztrack
Just calculate from the speed the winning car is going. eg
If its 115mph it is travelling at 51m/s so 0.1s will be 5.1m or 16feet8inches
What he said. A tenth at 140mph is a LOT MORE distance than a tenth at 105mph.

If you get beat by only a few tenths running 13.0's trapping at 105mph your car is fairly evenly matched with the one you are running. If you get beat by a few tenths running 9.80's at 140mph, the car that beat you is quite a bit faster than yours. The distance will be a lot more than the 13 second cars.

I once saw a heads-up race at TnT night between a car that ran an 11.4 and one that ended up running an 11.0. Both cars had almost identical reaction times(within a few thousandths of a second). The 11.4 looked SLOW when compared to the 11.0, even though it was less than a half second behind.
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Old Oct 24, 2005 | 12:55 PM
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Agree with a lot of what has been said in this thread. However, the old "rule of thumb" is .1 = ~1 carlength, and it is worthy of being a rule of thumb for your "typical" street car running at the track. Let's say mid 13 to mid 12 sec cars running 106 t0 112 in the quarter. That is a large portion of what I see at tracks and a .1 winner usually seems to be up by about a car length.

I totally agree with the guys who said judging track ET by car lengths in a street race is unreliable. There are so many factors on the street that you cannot measure, where you would be able to check them at the track. ie. wheelspin (as idicated by 60'), reaction time, etc. etc.

Last edited by TWS; Oct 24, 2005 at 01:01 PM.
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