What is it?

[BobsTrail]

Cleaning up under the hood and noticed the air intake from the filter to the engine has extra compartments off to the side. What are they??

 

[4Rager]

I've heard they are sound baffles that are meant to reduce noise at certain rpms/frequencies. Far from a professional opinion, but that's what I recall hearing.

 

[Mistaken]

When I swapped to the TRD intake, that doesn't have them, it was a lot louder than the oem setup. Definitely more restrictive.

 

[mo_mo]

Cleaning up under the hood and noticed the air intake from the filter to the engine has extra compartments off to the side. What are they??

Helmholtz resonators (inlet silencers/mufflers)

 

[Danimal]

Helmholtz resonators (inlet silencers/mufflers)

Correct, and they're tuned in terms of size to target certain problematic frequencies. Hence muliple are used of varying sizes/shapes.

It's worth noting that air doesn't flow through them, so they do not contribute to pressure drop through the intake tube.

Dan