what exactly is reaction time??...isant reaction time jsut how u react to the light??...the clock does not acculy start untill you start to move,,,,right??..like your reaction time doesent matter at all unless u are drag racing...it doesent have anything to dowith your quater mile time...right unless your aree racing some 1??....please w/b

 

there is much more to it than this........but I think the main thing your after is if it affects your quarter mile time; which is does not directly

you could hypothetically have a 3 second reaction time or a perfect light and run the exact same time............now there are different things that can 'bend' that rule, but on a normal car, as far as you know, it does not affect it

 

your reaction time is the amount of time that it takes from the point that the light actually turns green to the time that your car leaves the line

and yes - it does not affect your overall elapsed time for the 1/4 mile but as many pro racers know, it can make the difference as to whether or not you when the race when you are racing heads up

james

 

here are the basics

http://www.import-driven.com/m...&t=66

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by http://www.tracksideguide.com/Drag101/reactiontime.htm &raquo;</TD></TR><TR><TD CLASS="quote">
Reaction Time

Reaction time is the time it takes for the race car to move out of the starting beam after the green light on the tree illuminates. The reaction timer actually starts when the last amber light is illuminated. The reaction timer stops when the elapsed timer starts. There is either .4 or .5 seconds between the lighting of the lights on the tree depending on if the start is a pro or full tree start. Pro starts have a .400 second delay between lights while a full tree start has a .500 second delay between lights. If your front tires leave the starting beam exactly when the green light comes on you will cut a Perfect Light and the reaction time will be either .400 or .500 seconds. If you leave too early the red light comes on and you lose. Leave the starting line after the green light comes on and you are giving your opponent the chance to get ahead of you. So your job at the starting line is to cut the perfect light.

The reaction time is determined by three variables. Reaction time of the driver to the lights. The Reaction time of the car to the drivers action. And last but not least, the rollout of the tires in the starting line beam. We can refer to them as DRT (Driver Reaction Time), VRT (Vehicle Reaction Time) and Rollout Time(ROT).

Driver reaction time is measured from the time the driver sees a triggering event for the action until the action is completed. In other words, when we see the light turn green until the accelerator is depressed.

Vehicle reaction time is measured from the time the accelerator is depressed until the vehicle begins to move.

Rollout is measured from the time the tires start to move until the tire moves out of the starting line beam. Rollout may also be measured in inches for other calculations.

Here is a simple formula for total reaction time (RT).

RT = DRT + VRT + ROT

None of these variables will ever be zero. If they were we could wait to see the green light and then press on the accelerator. Since they are not instantaneous we must take into account the time delay of each.

Let's say that DRT is .200, VRT is .200 and ROT is .100. From the formula the total reaction time would be .500 seconds. As we noted earlier, the time between the last amber light on the Christmas Tree and the green light is .500 seconds. Since this time interval is the same as our total reaction time, when can theorize that if we start the driver reaction timer at the moment the last amber light illuminates we will have a perfect light.

As you can see, cutting a perfect light is not as easy as it would first appear. That is why practice makes perfect when it comes to racing.

You can tune your car, tires and driver to get better reaction times. Here are a few examples.

- If you wait to see the green light before reacting you will ALWAYS have a slow reaction time and more than likely lose the race. Tune your reaction to the lights by practice on a practice tree. You will find that your best reaction times will be related to the lighting of the last amber light.

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i have a small question, i was at the track last weekend.. did the NHRA move from .500 (or.400) as perfect to .000, or is it just my local track doing it different. It makes it a little easier on the slips, less confusion i guess

 

nhra has changed the the way you read your reaction times to 0. there still the .400 tree and the .500 tree but instead of .400 or .500 being perfect .000 is perfect.
ex.
.040=.440 0r .540 reaction time

 

Yeah they do that here in Sacramento now, too. Seems to be the new "standard".