CFM & MPG Carburetor myths.....

cool vid....explain this though.....
my 340 with 750DP, using the formula (which I don't use)..340 x max rpm 6200=21080000 div x 3456=609cfm engine requirement
with an 850DP still 609cfm but car ran almost 2/10nths quicker in 1/4.
??