A fuel injector size calculator helps engine builders and tuners determine the correct injector flow rate (in cc/min or lb/hr) needed to supply adequate fuel to an engine at a given power level.
Step 1 — Total fuel flow needed (lb/hr):
Total Flow = HP × BSFC
Step 2 — Fuel flow per injector (lb/hr):
Flow per Injector = Total Flow ÷ Number of Cylinders
Step 3 — Required injector size accounting for duty cycle (lb/hr):
Injector Size (lb/hr) = Flow per Injector ÷ Duty Cycle
Step 4 — Convert to cc/min (if needed):
cc/min = lb/hr × 10.5
(1 lb/hr ≈ 10.5 cc/min)