1. What is a Fuel Pump Sizing Calculator?

Definition: This calculator estimates the required fuel pump flow rate based on engine horsepower and fuel density.

Purpose: It helps automotive professionals and enthusiasts determine the appropriate fuel pump capacity for their engine.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( Q_f \) — Fuel pump flow rate (gallons per minute)
• \( HP \) — Engine horsepower
• \( \rho_f \) — Fuel density (pounds per gallon)
• 0.055 — Conversion constant

Explanation: The formula calculates the minimum fuel flow required to support the engine's power output at a standard brake specific fuel consumption.

3. Importance of Proper Fuel Pump Sizing

Details: Correct fuel pump sizing ensures adequate fuel delivery to maintain proper air/fuel ratio, prevent lean conditions, and support engine performance.

4. Using the Calculator

Tips: Enter the engine horsepower and fuel density (default 6.0 lb/gal for gasoline). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What's the 0.055 constant in the formula?
A: This accounts for typical brake specific fuel consumption (BSFC) of 0.55 lb/HP-hr, converted to minutes (0.55/60 ≈ 0.0092) and gallons (divided by 6 lb/gal).

Q2: What's a typical fuel density value?
A: Gasoline is typically 6.0-6.3 lb/gal, diesel is about 7.0 lb/gal, and ethanol is around 6.6 lb/gal.

Q3: Should I add a safety margin to the calculated flow rate?
A: Yes, it's recommended to select a pump with 20-30% more capacity than calculated to account for fuel pressure requirements and future modifications.

Q4: Does this account for forced induction?
A: No, turbocharged or supercharged engines typically require additional fuel flow - multiply the result by your boost pressure ratio.

Q5: What if I'm using E85 fuel?
A: E85 requires about 30% more flow than gasoline - multiply the result by 1.3 when using E85.