Reduce Exhaust Drone by Building a Helmholtz Resonator

[@byronrudnik2621]

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

[@NoWheelDrive]

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.

[@dannygillis69]

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

[@sc2dave1]

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

[@tl1024]

Gotta say, that's pretty slick!

[@lasalbay]

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

[@scgbtravis7180]

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

[@pan-pan2383]

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

[@FiveBoroNative]

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...!

[@DC_DC_DC_DC]

What's the connector pipe internal diameter and length you used? I'm about to kill exactly the same frequency range and peak area, and the chamber will be rather similar in diameter and length because I've coincidentally have these dimensions of material available from cutting up some OEM resonator housings!

[@FerasDishli]

Man U have a tough beechwood table. Nice video

[@_baller]

It's the guy from Full House

[@sticky40sx71]

That's not Joey... 🤔

[@henrylima6974]

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

[@peterdarr383]

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

[@ajello49able]

What not to do video!

[@joeyf504327]

no before/after in car vid ? lame

[@lucas.5am639]

Seriously.

[@user_mac0153]

Seriously Lame. How hard can it be.

[@42WallabyWaySydney]

This

[@stevewyatt3339]

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

[@node5884]

bra no guard on your cutter x_x

[@mikerammelt2420]

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.

[@FiveBoroNative]

Not at all. The larger the diameter of the chamber the greater the overall attentuation and the longer the chamber is the better it may deal with lower frequencies. The neck diameter and length obviously has to change along with the changes in those other parameters.

[@onse8982]

@@FiveBoroNative As you seem to know something about them, what diameter should the neck be compared to the exhaust diameter and should the pipe make a 90 degree bend or could it be just straight if it fits? Say I had a 2” exhaust, what size resonator neck would you recommend? Thanks.

[@FiveBoroNative]

​@@onse8982​@onse8982 there is going to be a relationship between the room you have to work with, the size of the chambers and frequency range you are targeting.

[@TECHNICIANIAM]

Does it kill rasp?

[@frankrofail8366]

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

[@kCI251]

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

[@Akiweb92]

LOL

[@AlejandroFrenzelZarza]

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

[@BalladeSports]

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

[@KrustyKlown]

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.

[@Akiweb92]

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!

[@allandrake4426]

U need a bench vise in the worst way

[@EvAlGi]

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.

[@RTLife]

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

[@69gringo69]

R/T Life hahahaha

[@brettsummer5070]

Im actually planning on doing this to my 5.7 hemi lol

[@Dnasty1]

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?

[@FiveBoroNative]

It's all about frequency ranges. The resonators can be sized to muffler whatever frequency range you are targetting, but they work best on lower frequencies (200hz and below) for example, but they can also work in higher frequency ranges, as well....

[@The_Clint_Beastwood]

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 :)

[@franklyle2798]

Same same. 1/4-wave and helmholtz are pretty much the same thing. Or at least they provide the same effect of standing waves to cancel out unwanted frequencies...

[@Kronaphasia]

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.

[@thejackgraves13]

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

[@joshbridger2230]

Have a picture? I'm curious I'm in the same boat with my borla atak on my cammed Silverado

[@FireRescueGuy]

Have your measurements/specs for yours?

[@FireRescueGuy]

Have your measurements/specs for yours?

[@thejackgraves13]

@@FireRescueGuy I used a 2.5 inch J pipe 32-34 inches Long. I forget where I ordered the J from sorry

[@FireRescueGuy]

@@thejackgraves13 I’m just going to have the exhaust shop make me one. Shouldn’t be that hard.

[@vgrzesiak]

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

[@SpeedyFagalas351]

Try this fix: kzbin.info/www/bejne/hqWYfoJmot-MY6s

[@trailerparkcryptoking5213]

This fix is for dummies and you recommended it!

[@randellgribben9772]

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

[@bassgitter3929]

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?

[@rtz7420]

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

[@GIZZMOTORSPORTS]

Does it do anything for WOT exhaust noise?

[@brandonovenephet4521]

Quarter wave length resonator

[@tartarsauce2601]

Is the speed of sound in meters/second?

[@Stazi75]

Use all metric units together.

[@peterdarr383]

1110 feet per second at room temps - - he calculated at 600*F for some odd reason.

[@theguy9234]

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.

[@johnbeer5242]

Sega Dreamcast music🙄🎵?

[@kas0016]

Those tails are massive.

[@SnipeYouFromMars]

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?

[@davejesse949]

No - the speed of sound varies only with temperature (in Kelvin). It's lower for someone in the mountains only because it's colder in the mountains.

[@gaziali6125]

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

[@Ter40]

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!

[@takechargeanddiy2378]

Thank you for your question. It is the total length measured through the center of the pipe. I used an average cross-sectional area measurement since the pipe was not consistent.

[@lyon666]

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

[@Zandermort]

what calculator did you use?

[@dylanlindsay5892]

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

[@jeff_desir]

Lol, wtf...

[@OEMPlus]

what engine do you have?

[@ssi079]

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

[@davidhoover2446]

Shane I thank you for your comment. Here is the link to take the handwork out of it: hyperphysics.phy-astr.gsu.edu/hbase/Waves/cavity.html#c4

[@raymondchen6720]

What happens if the Helmholtz resonator is too long?

[@peterdarr383]

It won't absorb the drone at your chosen highway speed. 10% too long and it targets 54 MPH instead of 60 for example.

[@jregamey]

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

[@takechargeanddiy2378]

Blocking off one side of the exhaust (assuming it is connected at some point and not true duals) would cause your resonant frequency to drop by half, making the resonance deeper. I wouldn't recommend cutting off the supply to half of your exhaust system though. That could cause a problem.

[@jasenhayes1710]

what about a 3in dual tip muffler.could i block 1 hole on that?

[@Van-tastic]

Those nails bro!?!?!

[@gatoescobarZ900]

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

[@ahmadkhair7938]

you saved my life

[@edism]

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

[@stephenchesterjr1364]

Ed a company called motordyne builds exhaust systems for Infiniti’s and Nissans and they use the helmholtz resonator in their designs and it does help but the j pipe will help as well , doing that soon with my new setup

[@edism]

@@stephenchesterjr1364 Thanks Stephen. After looking it up and learning more I understand that a J tube/pipe _is a type of_ damped Helmholtz resonator because it attenuates the sound in that position. I concede that all J tubes are Helmholtz resonators, however not all Helmholtz resonators are J pipes (eg. bass reflex in a speaker). I found out about self-tuning resonators too that have DC motors in them to adjust the cavity volume, very interesting. I hope your new setup works well! Let me know if you're going to upload a before and after clip!

[@stephenchesterjr1364]

Ed no doubt, I definitely will

[@edism]

@@stephenchesterjr1364 cool, I'll subscribe. I see you've already made some mods?

[@stephenchesterjr1364]

Ed yes sir.. k&n short ram intake, Gemini y pipe, cat delete, stock reso delete, added vibrant performance 1792 resonator, new 2.5” pipe, 2 new high flow invidia style 2.5 to 4” tip mufflers

[@matthewbarnes7932]

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

[@takechargeanddiy2378]

Thank you for your question. I placed mine before the muffler and after the cats. I believe placement will matter much more based on where it will fit than where the exact best spot is. The entire system has a resonance. Usually that is what causes the drone. So, placing it anywhere in the system will reduce that drone if tuned properly.

[@peter455sd]

Video could be reduced to 60 seconds

[@tooquic404]

Dem short tho....

[@s13drifterman]

Will it also make it quiter

[@klipseracer]

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.

[@smiley235]

Tyler Lee what are you on about. Of course you use holesaws on metal.

[@alanspangler5621]

Always oil up your metal... When youre using wood cutting bits

[@drongojonkins8945]

Bullshit. Any standard bimetal holesaw is designed for cutting steel as well as wood. You just need a good drill on the correct speed, a steady hand and a bit of finesse unlike our man here^

[@Bullchiton]

Funny, actual fabricator here. I use hole saws daily to cope tuning for roll cages.

[@psweber]

There are also carbide tipped ones

[@theguy9234]

Or you Could learn how cut better with a cutting wheel

[@ianflesher1736]

did it work?