1. What is a Fuel Injector Size Calculator?

Definition: This calculator determines the required fuel injector size based on engine horsepower, fuel consumption, number of injectors, and duty cycle.

Purpose: It helps automotive professionals and enthusiasts properly size fuel injectors for engine modifications and performance tuning.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• Injector Size — Fuel flow rate (pounds per hour)
• HP — Engine horsepower
• BSFC — Brake-specific fuel consumption (lb/HP·hr)
• N — Number of fuel injectors
• DC — Injector duty cycle (0-1)

Explanation: The formula calculates the fuel flow required per injector based on total engine fuel needs divided by the number of injectors and their operating duty cycle.

3. Importance of Proper Injector Sizing

Details: Correct injector sizing ensures optimal engine performance, prevents lean conditions that can damage engines, and avoids over-sized injectors that can cause poor idle quality.

4. Using the Calculator

Tips: Enter engine horsepower, BSFC (default 0.5 lb/HP·hr), number of injectors (default 4), and duty cycle (default 0.8). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What is BSFC?
A: Brake-specific fuel consumption measures how efficiently an engine uses fuel. Typical values range from 0.4-0.6 lb/HP·hr for gasoline engines.

Q2: What's a typical duty cycle?
A: Most tuners recommend 80% (0.8) duty cycle for safe operation, allowing headroom for variations.

Q3: How do I find my engine's horsepower?
A: Use dyno results, manufacturer specifications, or performance estimates based on modifications.

Q4: Should I use the same injectors for all cylinders?
A: Yes, for balanced fuel distribution, all injectors should be the same size in most applications.

Q5: What if my calculated size isn't available?
A: Choose the next larger standard size, but avoid going significantly oversized as this can affect idle quality.