I'm not a drag racer, but, IIRC when the car's nose/tires crosses the path of the christmas tree at a drag strip it activates a laser trigger that starts the chronometer. At the 1320 there's the other trigger that stops and gives you the time. That is why they make sure your car's nose is in the proper place so that you don't get a head start (gives you faster time if too far back) or that you trip the counter before light goes green (false start).
E.T. and reaction time have nothing to do with each other. E.T. is only the amount of time it takes your front tires to break the staging beam (2nd set of yellow) until your front tires break the beam at the finish line. Reaction time is the time it takes your front tires to break the staging beam from the time the last (third) green bulb lights. This is how you see cars run a faster time of the two, but lose the race due to a slower reaction time. Car "A" could run a 12.99 with a .08 reaction time and beat Car "B" that ran a 12.90 with a .25 reaction time. Of course this only applies to heads up racing where the first one to cross the finish line wins, not always the quickest time.
Test and tune is the best time to work on various aspects of your run. First you want to work on launching the car consistently and getting the best E.T. Then you work on bettering your reaction time.
Here is a perfect example of having a slower reaction time while focusing on getting the car down the track.
Test and tune is the best time to work on various aspects of your run. First you want to work on launching the car consistently and getting the best E.T. Then you work on bettering your reaction time.
Here is a perfect example of having a slower reaction time while focusing on getting the car down the track.