Velocity stack

wolram

Why would a velocity stack improve an ic engines performance?

Danger

It's pretty much just an air funnel. It straightens and accelerates the airflow into the carbeurator to make breathing easier. (And they look cool.)

brewnog

Low inlet restriction.

ray b

harmonic pulses play a roll too
liength of stack/ and total path vary peak power

both inlet and out lets size and path can move peak and total power
up or down the RPM range
so tuners play with size and shapes

some have tryed varyable leingth stacks that move in or out as RPM changes
and some vary valve opening timeimg or use one of 2 inlet valves at lower RPM in 4 valve motors

and yes they look cool too

Danger

Thanks for the additional info, Ray. I knew that manifold runner length did that, but not the stacks. Not that I'll ever use the things, but it's a good tip.