1. What is Injector Duty Cycle?

The Injector Duty Cycle (IDC) represents the percentage of time the fuel injector is open during one complete engine cycle. It's a critical parameter for engine tuning and fuel system design.

2. How Does the Calculator Work?

The calculator uses the IDC equation:

Where:

• \( PW_{ms} \) — Injector pulse width in milliseconds
• \( RPM \) — Engine speed in revolutions per minute
• 1200 — Conversion factor for 4-stroke engines (2 revolutions per cycle × 60000 ms/min ÷ 100 for percentage)

Explanation: The equation calculates what percentage of the total available time the injector is open at a given RPM.

3. Importance of IDC Calculation

Details: Monitoring IDC helps prevent injector overuse (typically kept below 80-85% for safety), ensures proper fuel delivery, and aids in selecting appropriate injector sizes when tuning.

4. Using the Calculator

Tips: Enter pulse width in milliseconds and engine RPM. Both values must be positive numbers. The calculator assumes a 4-stroke engine configuration.

5. Frequently Asked Questions (FAQ)

Q1: What is a safe duty cycle for fuel injectors?
A: Most manufacturers recommend keeping IDC below 80-85% to allow time for proper injector cooling and prevent static lock.

Q2: How does IDC relate to injector size?
A: Higher IDC values indicate the injectors are working harder. Values consistently above 80% suggest larger injectors may be needed.

Q3: Does this calculation work for 2-stroke engines?
A: No, for 2-stroke engines the denominator should be 600 instead of 1200 since they fire every revolution.

Q4: What factors can affect injector duty cycle?
A: Engine load, RPM, fuel pressure, injector size, and desired air/fuel ratio all influence IDC.

Q5: How is this different from injector pulse width?
A: Pulse width is the absolute time the injector is open, while duty cycle shows this as a percentage of available time at a given RPM.