Injector Size Calculator

Formula

To calculate the Injector Size (IS):

\[ IS = \frac{(HP \cdot BSFC)}{(NI \cdot \frac{DC}{100})} \]

Where:

\(IS\) is the Injector Size in pounds per hour (lb/hr)
\(HP\) is the Desired Engine Horsepower
\(BSFC\) is the Brake Specific Fuel Consumption in lb/HP-hr
\(NI\) is the Number of Injectors
\(DC\) is the Injector Duty Cycle in %

What is Injector Size?

Injector size refers to the flow rate of fuel injectors in an engine, typically measured in pounds per hour (lb/hr). It determines how much fuel can be delivered to an engine’s combustion chamber and is critical for achieving the desired horsepower while maintaining proper air-fuel ratios for efficiency and performance.

Example Calculation 1

Let's assume the following values:

Desired Engine Horsepower (\(HP\)) = 300
Brake Specific Fuel Consumption (\(BSFC\)) = 0.5 lb/HP-hr
Number of Injectors (\(NI\)) = 4
Injector Duty Cycle (\(DC\)) = 80%

Using the formula:

\[ IS = \frac{(300 \cdot 0.5)}{(4 \cdot \frac{80}{100})} = \frac{150}{3.2} = 46.88 \text{ lb/hr} \]

The Injector Size is 46.88 lb/hr.

Example Calculation 2

Let's assume the following values:

Desired Engine Horsepower (\(HP\)) = 400
Brake Specific Fuel Consumption (\(BSFC\)) = 0.45 lb/HP-hr
Number of Injectors (\(NI\)) = 6
Injector Duty Cycle (\(DC\)) = 85%

Using the formula:

\[ IS = \frac{(400 \cdot 0.45)}{(6 \cdot \frac{85}{100})} = \frac{180}{5.1} = 35.29 \text{ lb/hr} \]

The Injector Size is 35.29 lb/hr.