Question about speed stat

[CharmingClyde]

making a racing game and trying to correlate the vehicle's horsepower to the speed stat and using this calculator and the max speed stat (which 999999999 seems to be the limit for the engine) to get like accurate in game 1/4 mile times, but I'm wondering what exactly does "1" speed stat relate to, is it 1 pixel per second, minute, hour or 1 tile per second, minute or hour. I feel like if i figure this out i can just know how much of the speed stat i'd need to get to the 47 tile (116 pixels wide) drag strip i made and use the time from that to calculate how much horsepower it equals to.

 

i hope this made sense lol.

[Triangle]

It's something like miliseconds to move 1 tile = 1000 / (1 + ln(speed) )

 

Each point of speed essentially does less than the previous.