1. What is a Velocity Stack Length Calculator?

Definition: This calculator determines the optimal length of a velocity stack (intake trumpet) based on the speed of sound, resonant frequency, and a tuning factor.

Purpose: It helps automotive and mechanical engineers optimize engine intake systems for better performance.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( L \) — Stack length (meters)
• \( c \) — Speed of sound (m/s)
• \( f \) — Resonant frequency (Hz)
• \( k \) — Tuning factor (dimensionless)

Explanation: The speed of sound is divided by the desired resonant frequency to determine the wavelength, which is then scaled by the tuning factor to get the optimal stack length.

3. Importance of Stack Length Calculation

Details: Proper stack length tuning helps maximize volumetric efficiency at specific engine RPM ranges, improving power output and throttle response.

4. Using the Calculator

Tips: Enter the speed of sound (default 343 m/s at 20°C), desired resonant frequency in Hz, and tuning factor (default 0.25 for quarter-wave tuning). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: Why is the speed of sound important?
A: The speed of sound affects the acoustic wave propagation in the intake system, which varies with air temperature.

Q2: How do I determine the resonant frequency?
A: This is typically the engine RPM where you want peak performance, converted to Hz (RPM/60 × number of pulses per revolution).

Q3: What tuning factors are commonly used?
A: 0.25 for quarter-wave tuning, 0.5 for half-wave, but these may vary based on specific engine characteristics.

Q4: Does this account for end corrections?
A: No, for precise calculations you may need to add end correction factors based on stack diameter.

Q5: How does temperature affect the calculation?
A: Higher temperatures increase the speed of sound (approx. +0.6 m/s per °C), requiring longer stacks for the same tuning.