1. What is the Exhaust Pipe Diameter Calculator?

The Exhaust Pipe Diameter Calculator determines the optimal diameter for an exhaust pipe based on airflow (CFM) and desired gas velocity. Proper sizing ensures efficient engine performance and sound characteristics.

2. How Does the Calculator Work?

The calculator uses the exhaust pipe diameter formula:

Where:

• \( d \) — Exhaust pipe diameter (inches)
• \( CFM \) — Cubic feet per minute (ft³/min)
• \( velocity \) — Exhaust gas velocity (ft/s)
• 2.1 — Conversion factor

Explanation: The formula calculates the pipe diameter needed to maintain optimal exhaust gas velocity for given airflow.

3. Importance of Proper Exhaust Pipe Sizing

Details: Correct exhaust pipe diameter is crucial for maintaining proper backpressure, maximizing engine efficiency, and achieving desired sound characteristics. Too small causes excessive backpressure, while too large reduces exhaust velocity.

4. Using the Calculator

Tips: Enter CFM (based on engine displacement and RPM) and desired velocity (typically 100-150 ft/s for street vehicles). All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical CFM value for a street car?
A: For a 350 cubic inch engine at 5500 RPM, CFM is approximately 600-650 ft³/min.

Q2: What velocity should I aim for?
A: Street vehicles: 100-150 ft/s. Race applications: 200-300 ft/s. Muffled systems: lower end of range.

Q3: Does this work for dual exhaust systems?
A: For dual exhaust, divide total CFM by 2 before calculating each pipe's diameter.

Q4: How does pipe length affect the calculation?
A: Pipe length affects backpressure but not the fundamental diameter calculation. Longer pipes may need slightly larger diameter.

Q5: What about turbocharged engines?
A: Turbo systems often use larger diameters due to higher exhaust gas volumes. Consult specific turbo sizing guides.