Kegalodon!

Shark Week Inspires Us to do Something Really Wrong, All in the Name of Science

- Richard Holdener

Intake manifolds are both awesome and misunderstood, or at least the design elements. For many, intake manifolds are thought of as simple airflow devices, where more power from the intake comes from a simple process of improving the airflow of a said manifold. While this can be true, it is also possible for an intake that flows considerably less to make considerably more power. You see, there is much more to intake design than simple flow. The design variables that come to mind included not only airflow, but also runner length, volume, and taper, as well as the focus of this article: plenum volume.

For most, plenum volume is the open space above the runners, located between the exit of the throttle body and the entry of the runners. This is indeed plenum, but technically speaking, plenum volume, at least the portion included in Helmholtz resonance, includes not only the plenum opening, but also the air intake system and (open) throttle body, a single runner, and half of the adjacent cylinder (when the valve is open). For this test we are going to see how changes in the resonating volume alter power, but first, just what the heck is Helmholtz resonance?