1. What is the Injector Flow Equation?

The injector flow equation calculates the required fuel injector flow rate based on engine horsepower, brake specific fuel consumption, number of injectors, and duty cycle. It helps ensure proper fuel delivery for optimal engine performance.

2. How Does the Calculator Work?

The calculator uses the injector flow equation:

Where:

• \( HP \) — Engine horsepower
• \( BSFC \) — Brake specific fuel consumption (lb/HP-hr)
• \( n_{injectors} \) — Number of fuel injectors
• \( duty\_cycle \) — Maximum injector duty cycle (decimal fraction)

Explanation: The equation determines the minimum flow rate each injector must provide to support the engine's fuel requirements at maximum power.

3. Importance of Proper Injector Sizing

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

4. Using the Calculator

Tips: Enter realistic values for all parameters. Typical BSFC values range from 0.45-0.60 lb/HP-hr for naturally aspirated engines and 0.55-0.70 for forced induction. Duty cycle should not exceed 80-85% for most applications.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical BSFC value?
A: For gasoline engines: 0.45-0.50 (NA), 0.55-0.65 (turbo/supercharged). Diesel engines typically have lower BSFC values.

Q2: Why is duty cycle important?
A: Running injectors at 100% duty cycle can cause overheating and inconsistent fuel delivery. 80-85% is the recommended maximum.

Q3: How do I convert lb/hr to cc/min?
A: Multiply lb/hr by 10.5 to get cc/min (for gasoline with SG ~0.72-0.74).

Q4: Should I account for future power upgrades?
A: Yes, it's common to size injectors for 10-20% more power than current to allow for future modifications.

Q5: What about fuel pressure changes?
A: This calculator assumes standard fuel pressure. Flow changes with the square root of pressure ratio (new/old).