It's got nothing to do with carb or head cfm for just what an engine displaces in air at rpm, so a 589 is it's static displacement when off but at 5057 rpm the 589 actually displaces 1490227 cubic inches per minute or 862 cfm which is it's dynamic displacement.
It's just a formula I seen in one of my books seem ballpark enough to spec cid or rpm or hp which one your looking for or to compare different cid etc..
Should be for any amount of cylinders it obviously don't take in account for VE% I'm guessing the builder found that 1.4 cfm per hp is what average from his builds he did say something about higher out engines hp per cid use something like 1.3 or 1.2 I forget since 1.4 works close enough in my realm.
I seen that there formula was 78 hp short was the 5052 rpm at peak hp short to ?
the 1.4 rule of thumb says a 589 making 694 hp should peak at 5700 rpm ?
