different kind of question

Go down

different kind of question

Post  bbf-falcon on January 5th 2015, 6:13 pm

A guy ask me a question today that I really couldn't answer honestly.He wanted to know if there was an equation for elapsed time (et) and car lengths.In other words, if 2 cars left the line at exactly the same time and the winner was 1 car length ahead at the finish, would he be 1/10 quicker more or less.And would it be different whether it be 1/4 or 1/8 mi.

bbf-falcon

Posts : 8992
Join date : 2008-12-03
Location : Jackson, Ohio

View user profile

Back to top Go down

Re: different kind of question

Post  jones on January 5th 2015, 6:40 pm

I wouldn't think so, look at it like this. If you are driving behind someone at 45mph and you stay 3 sec back. Then speed up to 70mph and stay 3 sec back and the gap would widen.

So no.

Or are you trying to say you are dividing the 1/4 or 1/8 mile into 1/10's?

I'm sure there is a technical term for what your asking but I can't remember it. I'm more of a tangible knowledge guy.

You could figure out his et based off you mph / et and length of his car. Thats only if you was door to door with the exact same rt.

jones

Posts : 2212
Join date : 2008-12-02
Location : Philadelphia, MS.

View user profile

Back to top Go down

Re: different kind of question

Post  Wheelie58 on January 5th 2015, 6:59 pm

Somewhere, I have a spreadsheet that I did based on MPH... Feet per second...that would equate distance between the cars at the stripe, based on et difference.
Was pretty basic, even with rusty math skills.
Now, I let Crew Chief Pro figure all of that with a mouse click.
avatar
Wheelie58

Posts : 1840
Join date : 2009-08-08
Location : Alpharetta, GA

View user profile http://www.keithfulpmotorsports.com

Back to top Go down

Re: different kind of question

Post  BB94STANG on January 5th 2015, 9:05 pm

Car lengths would be different times based on how fast the cars were going at the stripe. Really fast cars one length apart would be much closer in times vs. a street race.
avatar
BB94STANG

Posts : 245
Join date : 2009-08-15
Age : 42
Location : Winchester, Ohio

View user profile

Back to top Go down

Re: different kind of question

Post  FalconEh on January 5th 2015, 9:58 pm

I would have to offer No, there are too many variables and not enough constants for it to remain consistent. If the car that is 2-car lengths behind spun the tires or slept it could be out MPH-ing the winning car making the closing rate inconsistent as an example. Would be reasonable for indexed cars given the index +/- would remain close to the same... except throttle stops etc will move where and when the power is applied throwing the numbers off again. No
avatar
FalconEh

Posts : 1430
Join date : 2014-08-21
Location : on the blacktop or in the mountains ????

View user profile

Back to top Go down

Re: different kind of question

Post  rmcomprandy on January 5th 2015, 10:15 pm

Exactly how long is a car length equated to be ...??

rmcomprandy

Posts : 5180
Join date : 2008-12-02
Location : Roseville, Michigan

View user profile http://www.rmcompetition.com

Back to top Go down

Re: different kind of question

Post  gmsmkr on January 5th 2015, 10:19 pm

rmcomprandy wrote:Exactly how long is a car length equated to be ...??

The length of the car your racing...
avatar
gmsmkr

Posts : 1364
Join date : 2014-06-22
Location : alabama

View user profile

Back to top Go down

Re: different kind of question

Post  Wheelie58 on January 5th 2015, 10:20 pm

...and factored for MPH
avatar
Wheelie58

Posts : 1840
Join date : 2009-08-08
Location : Alpharetta, GA

View user profile http://www.keithfulpmotorsports.com

Back to top Go down

Re: different kind of question

Post  bbf-falcon on January 6th 2015, 6:02 am

In my thinking,which is scary in its self,it really shouldn't matter how good of a pass either car made.The answer would be when the first car hit the stripe and the race was over.The ets and the car lenghts at that point should be the answer.mph shouldn't make a difference when the still shot is frozen at the stripe.jmt

bbf-falcon

Posts : 8992
Join date : 2008-12-03
Location : Jackson, Ohio

View user profile

Back to top Go down

Re: different kind of question

Post  rmcomprandy on January 6th 2015, 8:23 am

bbf-falcon wrote:In my thinking,which is scary in its self,it really shouldn't matter how good of a pass either car made.The answer would be when the first car hit the stripe and the race was over.The ets and the car lenghts at that point should be the answer.mph shouldn't make a difference when the still shot is frozen at the stripe.jmt

YES ... it is all about time and the space.

rmcomprandy

Posts : 5180
Join date : 2008-12-02
Location : Roseville, Michigan

View user profile http://www.rmcompetition.com

Back to top Go down

Re: different kind of question

Post  jones on January 6th 2015, 8:25 am

bbf-falcon wrote:In my thinking,which is scary in its self,it really shouldn't matter how good of a pass either car made.The answer would be when the first car hit the stripe and the race was over.The ets and the car lenghts at that point should be the answer.mph shouldn't make a difference when the still shot is frozen at the stripe.jmt

You time is still based on a fixed point (finish line) not the distance between the two cars. If he is running 200mph and puts a car length on you at the stripe with you running doing 100mph is not going to be the same as you both doing 100mph with him a car length in front of you.

jones

Posts : 2212
Join date : 2008-12-02
Location : Philadelphia, MS.

View user profile

Back to top Go down

Re: different kind of question

Post  FalconEh on January 6th 2015, 10:17 am

Wheelie58 wrote:...and factored for MPH

rmcomprandy wrote:
bbf-falcon wrote:In my thinking,which is scary in its self,it really shouldn't matter how good of a pass either car made.The answer would be when the first car hit the stripe and the race was over.The ets and the car lenghts at that point should be the answer.mph shouldn't make a difference when the still shot is frozen at the stripe.jmt

YES ... it is all about time and the space.

jones wrote:
bbf-falcon wrote:In my thinking,which is scary in its self,it really shouldn't matter how good of a pass either car made.The answer would be when the first car hit the stripe and the race was over.The ets and the car lenghts at that point should be the answer.mph shouldn't make a difference when the still shot is frozen at the stripe.jmt

You time is still based on a fixed point (finish line) not the distance between the two cars. If he is running 200mph and puts a car length on you at the stripe with you running doing 100mph is not going to be the same as you both doing 100mph with him a car length in front of you.

^^^^^^^^^^^^^^^^This

ET is just that Elapsed Time, in order to predict the "ET" of the distance in car lengths you need to measure the Feet/Second which is measuring the time it takes to cover the distance given... in this case we want to use 10th's of a second. So for argument sake if we use 120MPH - 176 FPS and 160MPH 234.67 FPS if the car length is 35' then it will take 2tenths to cover the distance at 120MPH and 1.5 tenths to cover at 160MPH FPS of the MPH will remain constant at that MPH.
avatar
FalconEh

Posts : 1430
Join date : 2014-08-21
Location : on the blacktop or in the mountains ????

View user profile

Back to top Go down

Re: different kind of question

Post  bbf-falcon on January 6th 2015, 10:25 am

If that's the case,then 35' would be equal 2 normal racecar lengths.correct?

bbf-falcon

Posts : 8992
Join date : 2008-12-03
Location : Jackson, Ohio

View user profile

Back to top Go down

Re: different kind of question

Post  FalconEh on January 6th 2015, 11:10 am

Essentially it would be the distance from the front tires or wing(whatever breaks the beams) of the second place car to the finish line beam. Yes I would probably call that 2-car lengths, the first car from the front tires back plus the gap to the second cars front tires.
avatar
FalconEh

Posts : 1430
Join date : 2014-08-21
Location : on the blacktop or in the mountains ????

View user profile

Back to top Go down

Re: different kind of question

Post  bbf-falcon on January 6th 2015, 3:35 pm

I think your probably fairly close with those calculations. Thx Wink

bbf-falcon

Posts : 8992
Join date : 2008-12-03
Location : Jackson, Ohio

View user profile

Back to top Go down

Back to top


 
Permissions in this forum:
You cannot reply to topics in this forum