Helmholtz Resonators w/Vacuum Actuated Cutouts

[GoodysGotaCuda]

Just sharing my latest modification to combat a drone I had at 2,000rpm.

I started with 24" resonator tubes from Synapes. In hindsight I should have just bought a tight 180° 2" bend and made my own. Lesson learned. Thus far, they have resolved my resonance issue at 2,000rpm. Before I could just feel my ear drums load up at 2,000, it'd go away around 2,300..but that puts me at 85-90mph on the highway... a little too fast, even for most Texas interstates.

The cutouts a sucked closed by engine vacuum and start to open when I mildly accelerate the engine, fully open at about 60-65kpa. We'll see how long they last, but I love the fact I get "on-demand noise" without flipping switches, pulling cables, or anything else.


Supporting info

J-tube Vendor
http://synapseengineering.com/synapseusa/products/nodrone.html?SID=76i1d7un3a55c1b9psfdog0eh7

Grassroots thread
https://grassrootsmotorsports.com/forum/grm/problem-exhaust-drone-solution-side-branch-aka-14-wave-resonator-or-helmholtz-resonator/129212/page1/

Calculation details
https://www.performancetrucks.net/forums/gm-engine-exhaust-performance-21/how-build-exhaust-resonator-tube-eliminate-drone-489463/

Vacuum cutouts
https://proflowexhaust.com/products/proflow-vacuum-actuated-exhaust-cutout-valve

[Brads70]

Interesting but only the last link works for me?

[GoodysGotaCuda]

fixed

[Convertcuda]

Nice Job! Is the drone at a different rpm now?

Ken

[GoodysGotaCuda]

Nice Job! Is the drone at a different rpm now?

Ken

Not that I noticed on the hour ride home, if it is, it'd be much higher than my cruising rpm. I'm driving the car for 6 hours or so this weekend, that'll give me a good feel for how it's doing.