I more thing I need to know
For example
Good or quick,length per speed is 6
Soft or slow,length per speed is 5
If horse beaten by 3 length on good or quicker surface it's beaten by 0.5s (3/6).But how it's beaten by 4 length on soft or slower which is 0.8s (4/5)
How 3 become 4
Length per speed
I'm not quite sure what you are getting at here but it sounds like you are assuming every horse is still going flat out at the time it crosses the line?
It may have been way out in front and eased right down the last half furlong or so, ditto for the 2nd place horse or it mat be fighting for 2nd/3rd place
It may have been way out in front and eased right down the last half furlong or so, ditto for the 2nd place horse or it mat be fighting for 2nd/3rd place