Velocity stack

A velocity stack is a device which is added on to the air entry of an engines fuel system, carburetor or fuel injection. It is designed to…

1. allow smooth and even entry of the air into the intake duct.

2. Slightly modifies the dynamic tuning range of the intake tract by functioning as a small reverse megaphone which can extend the duration of pulses within the tract.

3. May alter the dynamic tuning speed if it includes extra length thereby changing the tuned length to a lower rpm.

Often for modified engines the original air box and associated ducting is removed and velocity stacks may be installed to be an aerodynamic replacement for them.