What size fuel pump do I need?

Summit Racing's method: fuel needed (lb/hr) = peak hp × BSFC, then gph = lb/hr ÷ 6 or lph = lb/hr ÷ 1.6. Example: a 500 hp naturally aspirated engine at BSFC 0.5 uses 250 lb/hr ≈ 42 gph ≈ 156 lph, at your operating pressure (EFI 35–65 psi; LS ≈58 psi). Pumps are advertised at free flow, which drops as pressure rises, so read the pump's curve. Rule-of-thumb table: 255 lph ≈ 650 hp EFI NA / 500 hp boosted; 340 lph ≈ 850 / 600 hp (gasoline). For E85, redo the math with a higher BSFC.