high flow water pump
I am changing out my water pump on a ford 302 engine; this is for street use. I see "high flow" pumps advertised. I ordered a stock w/pump from NAPA and the impeller is 3-7/8" in diameter. On a high flow w/pump that I was interested in, the impeller is 3-1/2" in diameter.
1- is the impeller the main determinant of higher volume flow or
2- does the design and materials (billet, etc.) make more difference?
I would think that since the pulley (and hence rpm) is the same for all units, that the larger impeller is the most important consideration for street (stop and go) driving and that in a race situation, a smaller impeller would be more appropriate for high revs.
Can someone please educate me so I know what to look for?