Reduce Exhaust Drone by Building a Helmholtz Resonator 

That is one big Helmholtz resonator...! At almost 4.5 liters, I can't imagine that you'd have any drone after this was done. On my car I had drone between 70-130hz, but it was clearly the strongest around 82-100hz (94hz peak) so I went with (2) chambers (dual exhaust) that were 4 inches by 10 inches or about 1.925 liters after you factor in the 16 gauge thickness of the stainless tube for the canister. It worked well across the aforementioned frequency spectrum and they didn't take up too much space under the car which is what makes these types of resonators far more appealing for me than a 1/4 wave resonator (a.k.a. J-pipe). Good stuff...!

Great video! Finally instead of suggesting using dynomat or other mats or using other mufflers someone used math and physics approach to fix the drone noise. Thanks buddy! I'm definitely bookmarking this video and once I have a garage with workbench, vice etc I will try to do it too. Funny think my car has pretty expensive aftermarket exhaust and there is drone at cruise speeds and around 1800-2200 rpm. BTW another option is to use a stock exhaust and add valve (pressure or electronically) controlled section so you can have some exhaust noise when you want and still have a quiet daily driver. PS: I just watched another video made my Dynomax about their VT mufflers which have valves inside. But they just told me they no longer make them. Idk why but the idea was nice.

Gotta say, that's pretty slick!

I wanna have one of those KLX's again. Awesome bike.

I've built one too. I thought the tube had to be the same size as your exhaust. I ended up making one with a sliding tube so you could fine tune it. I agree with your results. Used my mobile to record the drone and some free software to analyse it on my PC.

Hi, nice video, how is the result after installing it? Your base tone was before 51dB at 129Hz and 75dB in total. What are the values after installing? Have you done the first measurement with your mobile telephone? what's the app you used? Thanks in advance

Thank you Mr. Cusack. This will help me defeat my muffler delete drone.

Man U have a tough beechwood table. Nice video

did it work?? guessing at the right temperature to use in volume calcs makes this a cut and try deal ... probably better off estimating too high a volume, then crushing in the tubing until max effect is reached.

I installed a Flowmaster 50 serie direct fit muffler on my 2016 ram 1500 sport. Great great sound but drone on highway... so I had to put back my stock muffler, that's too bad. Is there a fix for that, for example by replacing the resonators with those NDT (no drone technology) ones? Any advice would help!

I have a couple of questions... your plan showed you needed a neck piece of 8.5" in length, did yours end up at that length after you added your 2" extension for clearance from the actual exhaust? Also, was your cross-sectional area you figured for the "neck" calculated from straight pipe or the crushed (bent) pipe size? Thanks!

The tuning/hotrod community in Japan has been doing this since the early 70's. Look up Bosozuko muffler. They use these noise cancelling tubes to tune the exhaust note to cancel out most of the bass sound giving the exhaust note a very high pitch scream.

is it affecting the acceleration or anything? or just for sound ?

what calculator did you use?

Does it do anything for WOT exhaust noise?

Can you send a link to the audio tool app? Is it available for iphone?

Does it kill rasp?

for hot drilling, build a silly putty pond, and fill with water, this is more common with drilling glass

what engine do you have?

you saved my life

It is a nice system, I just wondering why you didn't made a cascade system of 2 or 3 chambers to have a bigger range? I missed the end measurements, like you did at the start of the video, that was a pitty.

It's the guy from Full House

Does this add hp? Or is it for noise reduction?

Is this thing mainly for lower rpm drone? I am having bad drone from around 1500-4000 rpm and I am trying to figure out what I should try first to resolve it. Should I try going with a vibrant bottle resontaor placed close to my engine before this?

Did you ever do a follow-up to indicate if this worked? I did a quarter-wave resonator on my last exhaust and want to do a helmholtz on my next one. Just curious if it worked out :)

did it work?

That calculator isn't working unfortunately. Since speed of sound is m/s, do the dimensions have to be in meters?

The temps won't be 600*F in the resonator pipe - - it's basically a dead-end.

On the end of the resonator where you put the flexible hanger bracket will allow your welds to break should be solidly mounted to the pipe beside it maybe some gussets at the lower end also by the elbow just saying I’ve been there broke that LOL Good video though

Those tails are massive.

Im fighting drone will it help if i block off a muffler? (Dual exhaust)

Great Video, could you link the website you used in order to figure out the size and freq?

Hey I have Q . I have 370z and I did muffler delete . It sounds amaizng but it just drones ALOT ! . Can I message you on your IG about this ? Thank you

Quarter wave length resonator

Holy jesus you complicated the crap out of a simple helmholtz resonator

I built one for my Silverado. I have a stage 3 TSP Cam and Long tube headers and No Cats. It droned terrible especially at 40mph or 70mph. I built a J pipe resonator or Helmholtz and now I am Drone Free. This thing works for Real

But wait. The speed of sound varies based on altitude doesnt it? So someone who lives close to sea level may want to use a different equation than someone in the mountains?

Can calculate all this, can’t fix a faucet drip.

I hope your Mom didn't mind you using her nice table! DOH

Is the speed of sound in meters/second?

Will it also make it quiter

Sega Dreamcast music🙄🎵?

What happens if the Helmholtz resonator is too long?

Do you attach it before the muffler or after the muffler?

Made it way more complicated than needed. All you need is same size exhaust pipe welded on at a 90 degree angle. Then cut it to proper length desired and then cap it.

bra no guard on your cutter x_x

here is a hint using a hole saw... clay... make a ring of clay around the hole you are cutting. and the lube will stay in,,, making the cut easier

Are you to fabricate one for me? All the exhaust shops I speak to, don’t know what I’m talking about.

Not a good design. Resonator should always be the same diameter as the exhaust pipe, not smaller.

When you hopped online and used a calculator "to finagle the sizes" without explaining where you went or how you came to your final dimensions you rendered your how to video useless. Any chance of sharing that info so we might duplicate the process?

U need a bench vise in the worst way

no before/after in car vid ? lame

What not to do video!

Dem short tho....

Jeez, use a vice dude. Gonna lose a finger there

Those nails bro!?!?!

This seems easy enough... LOL no shot at doing this at all!

J Tube resonator, a Holmholtz resonator wouldn't have dampened the sound.

You need some clamps, my friend. Great video otherwise.

I never saw a video that Didn’t explain shit at at all

Video could be reduced to 60 seconds

Lol, wtf...

Try this fix: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-Pt5MO0mzY-I.html

Do not use those circle cutting blades, they are for wood mostly. Use a stepped drill bit instead, they are made for that kind of stuff.

Or you Could learn how cut better with a cutting wheel