Helmholtz Resonator? (Patreon)

Attempted to make a Helmholtz resonator for the Accord to eliminate the very specific and very annoying rasp on decel. The build itself was successful. I can easily remove this capped pipe to change the length of it. The result was not successful (yet).

See, in order for these resonators to work they have to be a very specific length. There is a calculator online to help with this, but you need to know the operating temperature of the exhaust and hertz of the sound you’re trying to eliminate. I unfortunately know neither of these. I tried to use an audio decoder thing on my phone to record the hertz of the rasp, but it’s very quick and it was hard to pinpoint on the recording.

The plan is to shorten this pipe by 1” and test it. If it doesn’t work, shorten it again. The shorter it is the higher frequency it’s supposed to eliminate.

The goal with this is to remove the rasp but not make the car any quieter. It’s already quite quiet and I really don’t want to make it quieter with a bigger resonator.

I’ll follow up with results tomorrow!