1. What is the E85 Injector Size Calculator?

The E85 Injector Size Calculator determines the required fuel injector flow rate (in lb/hr) for engines running on E85 fuel based on engine horsepower, number of injectors, and duty cycle.

2. How Does the Calculator Work?

The calculator uses the following equation:

Where:

• \( HP \) — Engine horsepower
• \( 0.7 \) — BSFC (Brake Specific Fuel Consumption) factor for E85
• \( Number of Injectors \) — Total injectors in the system
• \( Duty Cycle \) — Maximum injector duty cycle (typically 0.8 or 80%)

Explanation: The equation accounts for the higher fuel flow requirements of E85 (approximately 30% more than gasoline) and ensures injectors aren't run at 100% duty cycle.

3. Importance of Proper Injector Sizing

Details: Correct injector sizing is crucial for engine performance and reliability. 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 at the wheels (for dyno numbers) or crank (for manufacturer ratings). Use a realistic duty cycle (typically 0.8 for street applications, 0.9 for race applications).

5. Frequently Asked Questions (FAQ)

Q1: Why is the BSFC higher for E85?
A: E85 contains less energy per gallon than gasoline, requiring about 30% more fuel flow for equivalent power output.

Q2: What's a typical duty cycle for injectors?
A: 80% is common for street applications, allowing headroom. Race applications may use 90-95%.

Q3: Should I round up my injector size?
A: It's generally safe to round up to the nearest available injector size, but avoid going significantly larger than needed.

Q4: Does this work for turbocharged engines?
A: Yes, as long as you're using the correct horsepower number (including boost power gains).

Q5: What about ethanol content variations?
A: This calculator assumes E85 (85% ethanol). For different blends, adjust the BSFC factor accordingly.