Efi Injector Size Calculator For International

Injector Size Formula:

\[ Injector_{lb/hr} = \frac{HP \times BSFC}{n_{injectors} \times duty\_cycle} \]

Horsepower (HP):

Brake Specific Fuel Consumption (BSFC):

lb/HP-hr

Number of Injectors:

count

Duty Cycle:

fraction

Required Injector Size:

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1. What is the EFI Injector Size Calculation?

The EFI injector size calculation determines the required fuel injector flow rate (in lb/hr) based on engine horsepower, fuel consumption characteristics, number of injectors, and their duty cycle. This is essential for proper engine performance and fuel delivery.

2. How Does the Calculator Work?

The calculator uses the standard injector size formula:

\[ Injector_{lb/hr} = \frac{HP \times BSFC}{n_{injectors} \times duty\_cycle} \]

Where:

\( HP \) — Engine horsepower
\( BSFC \) — Brake specific fuel consumption (typically 0.5 lb/HP-hr for gasoline)
\( n_{injectors} \) — 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 while accounting for the number of injectors and their maximum recommended duty cycle.

3. Importance of Proper Injector Sizing

Details: Correct injector sizing ensures adequate fuel delivery at maximum engine load while preventing injectors from operating beyond their optimal duty cycle. Undersized injectors can cause lean conditions and engine damage, while oversized injectors can affect idle quality and low-speed drivability.

4. Using the Calculator

Tips: Enter engine horsepower, BSFC (use 0.5 for naturally aspirated gasoline engines), number of injectors (typically equal to number of cylinders), and desired maximum duty cycle (typically 0.8 for safety margin).

5. Frequently Asked Questions (FAQ)

Q1: What BSFC value should I use for my engine?
A: For naturally aspirated gasoline engines, use 0.45-0.50. For turbocharged engines, use 0.55-0.65. Diesel engines typically use 0.35-0.45.

Q2: Why use 80% duty cycle?
A: Running injectors at 80% of maximum capacity provides headroom for transient conditions and helps prolong injector life.

Q3: How do I convert lb/hr to cc/min?
A: Multiply lb/hr by 10.5 (for gasoline) to get cc/min. Example: 24 lb/hr × 10.5 = 252 cc/min.

Q4: Should I size for peak horsepower or normal operating range?
A: Always size for peak horsepower requirements to ensure adequate fuel delivery under maximum load.

Q5: What if my engine has secondary injectors?
A: Calculate primary injectors separately from secondary injectors, accounting for when each set activates.