Improve the Efficiency of Engine:

A velocity stack is also called the trumpet or colloquially the air horn. It was Stuart Wilborn who popularized the usage of velocity stacks into the mainstream. They are placed at the intersection of the air intake on an engine and serve in assisting the engine to draw in as much air as possible. The unique shape of the stack with its flared end helps in facilitating smooth airflow into the engine. It is used for two purposes:

• Allow smooth and uniform entry of air at great speeds into the intake tract with the flow stream following to the pipe walls called as laminar flow.
  
• Adjust the dynamic fine-tuning array of the intake tract by working as a hollow pipe which can be adjusted in accordance with the frequency of pressure pulses built on its length size as found inside the track.

The dimensions of the stack are important as a properly tuned length and specific diameter with a good taper helps to marginally increase the intake pressure over the ambient atmospheric pressure by making use of resonant frequencies of the stack. This helps the engine to have a slightly denser charge of air as the intake valves are opened. So, this translates to more fuel being burned being proportional to the more power usage over a specific range of RPM. Depending upon the engine and the geometry of the velocity stack occur at different places in the engine’s rev range

However, velocity stacks are not good looking but what they perform, they add much more power to the engine by keeping them cool, even more than air filters. As more air intake leads add more power in the engine, and it maintains the right tuning of your engine that leads to better service life.

Why are they Important?

Velocity Stacks

You can spot velocity stacks on cars for basically three technical reasons and each of them primarily focuses on getting more air sacked in the engine.

• Firstly, it’s an easy method or way to change the length of your intake helping you greatly in a tuning of the engine. You can either have a short or long velocity stack as different engines perform differently with a variety of lengths.
  
• Secondly, they allow the efficient and smooth entry of the air that rushes into the intake. The smoother fuel contributes to burning more fuel which leads to more power generation from the fuel burnt. The trumpet-shaped curves help in pushing the outside air. On the contrast, a straight pipe would not get the external air rushing and struggle whereas a curve lets more air smoothly entering inside.
  
• Lastly, the cleaned and controlled airflow prevents the entry of certain kinds of carburetors being non-plenum from barfing the fuel and catching fire. The physics being dealt in this subject is equally important as the above two points. The added and cleaned up the intake of air that a velocity stack gives is hence necessary for non-plenum carburetors.

Factors:

Inserting the right size of the velocity stacks is necessary to improve the well-tuned engine’s peak powered output. Also knowing the right length is crucial as it involves engineering and factors like amount of effective value, duration, the timing and ramp velocity, as well as the precise distance between the exhaust valves and the exhaust collector being optimized for single speed delivery, etc. So, as a tool for making an engine to sound like a monster, these stacks are unmatched but whereas a tool for improving the airflow, these stacks may just seem an old-school tradition yet being relevant in today’s engine tuning after all looking badass.