the change between each light is 0.4sec, when racing if you get less than 0.4 reaction time you "red-light" as you are deemed to have left on or before the last organge light and before the green.
straight from the Willowbank website:
QUOTE
Working The Lights
Before diving into an explanation of how to "cut a good light", you must remember two things. 1. Each lane is timed independently of the other, and 2. The timers do not start when the green light comes on!
To give an extreme example, if you were to sit on the start line until your opponent crossed the finish line and then leave, you may run a time much closer to your dial-in, , but he would easily win the race, simply because he had a much better reaction time - like around 15 seconds better! In real racing this sort of thing happens all the time, except the difference between reaction times is in hundredths of a second.
When you get your time slip after a run, look at your reaction time. Compare it to your opponent. Reaction times work on a simple principle. It measures the time from when the last amber come on to when your front wheel clears the start line beam. Now as there is exactly 4 tenths of a second between lights, it then follows that a "perfect light" will be four tenths of a second - meaning that the vehicle has cleared the stage beam at exactly the same time as the green light came on. This is shown on the time slip as .400. Anything less than this means that you left too early and red lighted (fouled) and any more than this is wasted time sitting at the start line.
Most newcomers to racing leave when the green light comes on. This will give a reaction time of well over a second. For example, if you pulled a 1.12 reaction time and your competition ran a .460, you have given away over six tenths start right at the start line. For a more graphic example, with two cars of the same performance running 100 mile an hour in the quarter mile, this .66 wasted at the start represents 96 feet or about 6 car lengths at the finish line!
So, lesson number one in cutting a good light is to forget abut the green. Try leaving as soon as you see the last amber light. You'll probably be surprised to find you did not red light. And when you get your time slip, you will be amazed at the difference in your reaction time. After that it is largely up to you and your vehicle. You should try to improve your reaction times until you can run in the mid fours. Forget about running .40's every run. Only very experienced racers with well set up cars can run reactions consistently in the low fours.
If you are puzzled why you can leave before the green light comes on, without triggering the red light ....,well, its simple. It's to do with reaction times. Firstly, your reaction to a signal, in this case the last amber will be around .17-.20. Medical studies have pegged average human reaction times at around this time. Secondly, the reaction time of your vehicle itself - the time it takes from when you stomp on the throttle to when your front tyres move out of the stage beam.
Therefore you can see that it takes almost half the time between the last amber and green to react and stand on the throttle, plus more than this time again, for your vehicle to move forward and clear the start line beam. Naturally, the slower the vehicle, the slower the "vehicle reaction" time is and the earlier you can leave on the lights.
This takes practice and varies from vehicle to vehicle.
