1. What is the Fuel Injector Size Calculation?

The fuel injector size calculation determines the required flow rate (in pounds per hour) for fuel injectors based on engine horsepower, fuel consumption, number of injectors, and duty cycle. Proper sizing ensures adequate fuel delivery for optimal engine performance.

2. How Does the Calculator Work?

The calculator uses the injector size equation:

Where:

• \( HP \) — Engine horsepower
• \( BSFC \) — Brake specific fuel consumption (typically 0.45-0.55 for NA engines, 0.55-0.65 for turbo engines)
• \( n\_injectors \) — Number of fuel injectors
• \( duty\_cycle \) — Maximum injector duty cycle (typically 0.8 or 80%)

Explanation: The equation calculates the fuel flow required per injector to support the engine's power output at maximum load.

3. Importance of Proper Injector Sizing

Details: Correct injector sizing is crucial for engine performance. Undersized injectors can cause lean conditions and engine damage, while oversized injectors can cause poor idle quality and drivability issues.

4. Using the Calculator

Tips: Enter engine horsepower, BSFC (use 0.5 as default for naturally aspirated engines), number of injectors (typically 4, 6, or 8), and desired maximum duty cycle (typically 0.8 for safety margin).

5. Frequently Asked Questions (FAQ)

Q1: What is a typical BSFC value?
A: Naturally aspirated engines: 0.45-0.50, Turbocharged engines: 0.55-0.65, High-performance engines may be higher.

Q2: Why use 80% duty cycle?
A: Running injectors at 100% duty cycle can cause overheating and inconsistent fuel delivery. 80% provides a safety margin.

Q3: How do I convert lb/hr to cc/min?
A: Multiply lb/hr by 10.5 to get cc/min (approximate conversion).

Q4: Should I add extra capacity for future upgrades?
A: It's common to add 10-20% extra capacity if planning performance upgrades, but don't oversize too much.

Q5: What about different fuel types?
A: This calculation works for gasoline. For E85, multiply result by 1.3-1.4 due to its lower energy content.