What is my 40 yard dash? And any advice on how to increase my 40 yd dash?

I raced someone today and i was about a yard behind him, and he runs a 4.7. When i ran it a couple years ago it was a 5.1 but it was windy and my start was wack, i know im faster than that. Its somewhere between a 4.7 and 5.1?? Thanks...and any advice on how to get it faster. Not the start, just to be faster at sprinting 40 yardsWhat is my 40 yard dash? And any advice on how to increase my 40 yd dash?
your top speed sounds like its around 10 yards per second so that would make your time 4.8 if u were a yard behind him. plyometrics, flexibility and strength training will help u improve. also, try to lengthen ur stride length, run with a relaxed neck and face and really concentrate on pushing hard off the ground on every stride. u may find ur time is instantly improved.