One way, the best way, is use lbs/hour of fuel. Gasoline, weighs roughly 7lbs/gallon. If you fuel pump has a rated flow of say 140 gallons per hour, multiply that number, by 7, which is how mayny pounds in one gallon. So, you have 840 lbs/per hour of potential fuel flow from that pump. Considering it takes roughly 300 lbs per hour to supply 700hp, and somewhere around 500 for 1000hp, that 140 gallon pump, will work for both applications.
Now, you also need adequate fuel line size, minmal bends and turns, etc. Also, the closer to masex out, the pump heats up the fuel more, which is a negative. So, Some of these monster pumps, are totaly overkill. Which, doesn;t hurt anything, but, it just costs more. Thats a good way to look at it though, the lbs/hour that the engine requires, or is using to make its power, and, use 7lbs per gallon of fuel, to do a simple equation to figure it out.
Frank
Advanced Performance
www.get-ap.com