using SCIENCE to ELIMINATE exhaust drone: I FINALLY did it!

[@LawrenceTolman]

The LSA install starts next! I gotta say, this exhaust journey was a long one, and usually it doesn't take quite so many changes to make me happy with the sound, but I think we're finally there guys.

[@erichildreth7562]

I am glad that you finally got this fixed! Nice work and the look on your face when you passed the cop car was priceless and yes it gave me a good laugh and yes I have done that same look too!!

[@cadeflorez707]

Yeah man thank god I don’t think we could have taken another video about the same thing again.

[@dannyflood3291]

Lol passing the cop was great, and that resonator made a difference!! Good work man!!

[@hydrocarbon82]

It's funny you're literally using science to fix this, in a time where trust in science is at an all-time low. As you found it's recommended to make it temporarily adjustable. Cut the j-pipe a few inches longer and use one of those expanding drain plugs to move the 'cap' til it sounds perfect. You can even finalize it with a silicone coupler for later adjustments, if things ever change.

[@EngineeringGoneWrong]

Took me about as long on my truck so don't feel bad but now it sings! I've got a bone stock Lm7 with intake, short tube, stock cars, Flowmaster super 10, 2" diameter quarter wave setup identical to yours, and duals out the back as God intended it lol. Nice video.

[@jaredshaffer3901]

You talked about doing a full length or half length resonator. Just FYI, those wouldn't work because with a half length (full length when you consider the wave going down and back) and full length, the wave would be back in phase. With quarter wave length, (half wave length full travel distance) it is 180 degrees out of phase, which causes the cancellation.

[@LawrenceTolman]

great info I didn't even consider!

[@sik59rt]

Now that’s science !

[@robertwillis4061]

So in theory with the drone at 95hrz that needs a 36" + quarter length resonator, would an eighth part length work at 18" in length?

[@jaredshaffer3901]

@@robertwillis4061 no, that would put the wave at its peak (1/4 wave) when it arrives back to the exhaust stream. You can do 1/4 wave length, 3/4 wave length, 5/4 wave length and so on, because the full travel distance ends on a half wave length.

[@robertwillis4061]

@@jaredshaffer3901 ok so a negative number of quarters would work to put the wave out of phase to the primary wave from the engine. My reason is I have a large bore exhaust on my car that is used daily. Unfortunately longer distance drives become very tiring due to resonances it the exhaust.

[@steveh4837]

I love your scientific approach to the drone! Essentially, you installed a Helmholtz resonator. I've installed them in piping systems in natural gas processing facilities where pulsations from reciprocating compressors will cause vibrations and noise due to pulsations in the pipe. A large part of you did was change the natural resonant frequency of the piping (exhaust) system farther away from 117hz. You did this by adding pipe length of the resonator (which is why drone now occurs at lower rpms). The further away your resonant frequency between pulsations and exhaust system, the less drone you'll have. Its the same idea where a tire that's out of balance vibrates at a certain speed on the highway, and when you speed up or slow down it goes away. Those tire vibrations were matching the suspension's resonate frequency. I wouldn't be surprised if you went back to the original muffler you wanted to use (the hush power, as I recall), you'd still keep the drone effect down because the resonator is now installed. Maybe an experiment for another day. Great work!

[@diannafiredal]

As far as I've been able to determine from the literature, a helmholtz resonator is by definition an enclosed volume of air with a narrower neck/opening, where the volume of air and the relative dimensions of the neck/opening all influence the damped frequency. As opposed to a quarter wave resonator which is just a piece of pipe and the length is the only variable used to influence the target frequency.

[@Yamahog]

Great explanation Steve. Now if Lawrence was to make the fixed resonator section that's over top of the muffler " Unfixed " and fitted with a slide-able section there..... he could theoretically move the resonator section back and forth to " tune" the cavity to his needs then clamp it into place.....[ Yes Guys .... like a trombone slide ....😎] ..

[@A55455In47I0n]

isnt this a quarter wave resonator? or does this design work in both ways?

[@danieldimitri6133]

A quarter wave resonator is about the timing of sound wave reflections. A hemholz is where a volume of air acts like a spring and a moving mass of air in a smaller pipe acts like a weight. They can accomplish similar things and are technically happening at the same time in both solutions. But generally if the length of the pipe and it's sound wave reflections is a quarter wave or less (as in the pipe is that length or longer) then the reflections may have a stronger effect than it's hemholz properties. But if the pipe is a shorter length especially and both sides are open and there is a volume of a larger diameter on one or both sides of it then hemholz properties are probably dominant. At least that's how people in the speaker enclosure building communities look at it. You could use either effect on the flowing exhaust or in parallel to it but using hemholz might require smaller piping and restrict airflow so headers are usually designed for reflections and intake manifolds are often less than ideal because when they are designed for reflections in a low rpm range the runners get excessively long. As far as noise cancelling the refected wave might have a bit of a comb effect with intervals of cancelation through the spectrum. Hemholz has a different phase profile.

[@DieselRamcharger]

he made a standard muffler the most complicated way possible.

[@fullautophx]

I’ve made many many of these over a 20 year custom exhaust career, adjustable and various lengths. For some reason 28” is the magic spot, it never fails to relieve the drone.

[@walkerforsyth6221]

I wonder how this affects on turbocharged cars or even like a big diesel, any experience in those? in that case I'm afraid the way lights are so far apart that resonator would have to be feet and feet long...

[@loganwightman1325]

Have you ever done one on a V6?

[@drewdavis239]

Can you give examples of cars the 28" worked on? Some caculations suggest i need 31 to 33 " for 3000/3100 rpm (highway speed) his spread sheet says 25 and change for my 6 cylinder bmw.

[@SilvaDreams]

​​@@walkerforsyth6221It wouldn't affect a turbocharger since they feed the hot exhaust from the headers and most well designed mufflers have baffling inside that effectively works the same way.

[@psdaengr911]

Slicing the end of the resonator tube at a 45 degree angle would make it work over a wider range of frequencies just as the 90 degree bend did. Also the placement of the resonator at the position along the length of the exhaust where the resonant vibration is highest would make it most effective.

[@YakoHansen]

Do you mean a 45 degree end, at the end of the resonator tip?

[@matthewyoung4877]

Yes at the end. That will also reduce the amount of cancelation you get at those specific frequencies. So in other words you will get a broader spectrum of cancelation but less actual noise reduction which is measured in dB.

[@flubyux2]

Just to be clear, it’s a hemholtz resonator. The drone frequency happens in the range of rpm that is a multiple of how many cylinders you have. The temp of exhaust gas will alter that rpm point a little due to the speed of sound at those given temps. Cold exhaust pipes will resonate at a slightly diff rpm than hot exhaust pipes. And you either choose the rpm at which your engine drones/resonates or the rpm at which you spend the most time driving in. These rpms are usually different. So it’s ultimately up to each persons needs to determine the final length of pipe. Edit: ps: the diameter of the resonator should be the same size as the exhaust pipe it’s connecting to. Sometimes that’s not possible so the equation just has to be adjusted.

[@Yves998]

People tends to use smaller pipe just for the clearance haha.

[@diannafiredal]

As far as I've been able to determine from the literature, a helmholtz resonator is by definition an enclosed volume of air with a narrower neck/opening, where the volume of air and the relative dimensions of the neck/opening all influence the damped frequency. As opposed to a quarter wave resonator which is just a piece of pipe and the length is the only variable used to influence the target frequency.

[@drewdavis239]

How do you adjust for size? I have 3" but can only fit a 2.5 " j pipe

[@FizzGiGG55123]

@@drewdavis239 the volume of the helmholz resonator is your target, adjust accordingly so the resonant frequency of the resonator is what you are attempting to cancel out... at least that is my understanding.

[@1stAxelKain]

When I built the Helmholtz resonator for my 454 burb, I actually got a more effective result by calculating by the affected RPM, after trying it by a frequency reader like you did, which ended up needing to be a little bit shorter, and solved my drone completely at 1800 rpm!

[@speedycpu]

Did you do any temperature calculations? Did you use the exhaust gas temperature, or the outside air temp? It should be the higher exhaust temp. If you used the lower outside temp and pressure, it would skew results a bit. Would be best to have a tube you can adjust inch by inch up/down and see where it is quietest.

[@1stAxelKain]

@@speedycpu yep, referenced average exhaust temp in the pipe area I was planning to install it. Using the frequency meter got me close, but doing the math for the rpm was more effective for me. I designed mine to be adjustable by a few inches for this exact circumstance.

[@chimerical5691]

@@1stAxelKainhow’d you manage to make it adjustable?

[@1stAxelKain]

@@chimerical5691 used 3in OD pipe off the exhaust and a capped section of 3in ID with a clamp. Once I was satisfied, welded it up.

[@videomaniac108]

Consider the possibility that if you add another reactive acoustic element to your exhaust system you might get "self noise", where exhaust pulses at a particular frequency might oscillate back and forth between the elements and reinforce the amplitude of the pulses and result in a louder sound.

[@roundtownKen]

If not done correctly you can get noise back/added. Done with all the calculations - adding a cancelation wave at the correct frequency - works.

[@blairanthony3801]

May I suggest an adjustable resonator. Similar to a trombone slide. Fully tunable an adjustable

[@y5mgisi]

This is what I'm planning. Make it adjustable, and then weld it where I like it after testing.

[@NitroNuggetTV]

Imagine attaching an electronic actuator to it and getting some code written so it'll can counter drone at all rpms based off of gear and road speed, for situations like he mentioned at 13:12. Wildly over complicated, prone to failure and almost completely unnecessary but would be cool lol

[@otm646]

@@NitroNuggetTV I'd love to see something like that, slick as hell. Or you could open up progressive chambers with solenoids to change the resonance "length" .

[@pgtmr2713]

@@NitroNuggetTV An Arduino controller should be able to do it. You can learn it quick, also borrow code from other projects to get what you need. Such as how to get the rpm from the car. Some guy built an rpm gauge for his Audi and I was able to use a bit of the code to figure rpm for a completely different project. Arduino Uno was about $10 when I bought mine. KZbin to learn the programming.

[@chuckthebull]

@@NitroNuggetTV stepper motor and an arduino and bam,,,i could code it.

[@3VJohnny]

Hey man nice work on this is something that I am planning on doing on my exhaust on my truck as well. I've played around with exhaust damper weights and they work as well but the quarter wave resonator is something I'll be definitely doing myself. One idea that I've had when I do mine, is to get a slightly larger diameter piping for the very end so that you could slide it over the main section of the quarter resonator so that you could fine-tune it. And then you could use a lap joint clamp so that you could tighten it down once you find your right length. It's just a thought because it would allow you to gain a few inches or shorten it depending on your targeted frequency. When I had spent a lot of time researching this over the past year I found that 28 to 35 seem to be the ideal length for a lot of the V8 vehicles but it's not always easy to confirm which one is best per application. Nice work

[@omnipotent87]

After watching your video i made related resonator called a helmholtz resonator. Its a little bit smaller and requires a few more variables. This worked fantastic and want to thank you for the idea other wise i would have never considered it. This was put on a 1989 F250 with a cammed 351.

[@Oldsoldiersays]

im so glad you figured this out all on your own and no one recommended this exact thing to you 5 videos ago.

[@LawrenceTolman]

I’ve known about this truck for years and have built resonators on previous trucks, but I waited to install this one because the overall sound level of the system was not to my liking before. Once I got the volume and overall sound where I wanted, I could easily tackle the specific drone frequency. A resonator like this won’t work if it’s too loud everywhere

[@El_Chompo]

Really cool man. I did a ton of exhaust experiments myself regarding drone, some are on my channel but I wish I documented more. Basically I found out that if you reduce the exit size of your muffler even just a small amount it can eliminate a huge amount of drone wile hardly creating any exhaust restriction. Additionally, if you use a turn down so the exit of the exhaust faces towards the ground instead of straight out the back, it hugely helps with drone too. That resonator small pipe is really cool though and I will have to try that technique sometime. It's perfect for being quite while not reducing flow or performance at all.

[@bobqzzi]

If you can find a piece of tubing that slides over the outside of the resonator, you can make a variable length one so you can determine the best length empirically before making a fixed one again.

[@SuburbanK2500]

I was going to post the same thing, but checked to see if anyone else posted the same idea ;)

[@meathead365]

Like a rusty trombone

[@steve6992]

What do you think about using a slip-on extension to your resonator so you can adjust the length and tune the sound of your exhaust

[@johnrodrigues2018]

Like a trombone 😆

[@steve6992]

@@johnrodrigues2018 precisely

[@ArmySigs]

Seems legit

[@TheDrtye]

Absolutely would work.

[@gm0hzi]

you beat me to it , some adjustment takes out the variables in the temperature calculations

[@MrLightning54]

I've been doing exhaust stuff to my 2019 5.0 F150, and have been through too many exhaust configurations myself, lol. I do enjoy doing that stuff though, yours turn out really well btw! Now I'm back to the factory single 3" exhaust with a boost actuated Loudvalve to bypass the muffler and resonator when the hammer drops, and I should've done this in the beginning, I'm finally happy with it. I'm liking all your videos, they remind me of my missions!

[@MrGivmedew]

This is the way I prefer it as well. My ECU is programmed to open the dump at WOT and stay open for a few seconds once no longer at WOT.

[@gordowg1wg145]

Two points - It needs to be 1/4, or 3/4, or 5/4, etc. - because the sound wave reflection from a closed end stays in phase - so to get the cancelling pressure wave 180 degrees to the originating source it needs to work for that. If you make the resonant pipe a slip joint you can move it longer or shorter to fine tune the length for cancelling wave, then weld it in place - i would suggest a clamp so it can easily be adjusted for any changes you make to the sytem that might alter the drone point. Oh, just as the length will affect the frequency, the diameter will affect the amount of attenuation it does.

[@sebastianmuglia7451]

I definitely love the video without music. Very soothing hearing you work

[@terryvincent8405]

I built a pair of these for my 04 Titan after header install. Worked amazingly well!

[@notamouse5630]

Tip: Pack some steel wool gently at the end and pin it to broaden the anti-resonance and damp more drone frequencies.

[@nobodynoone2500]

Bad idea. Traps moisture, and more importanly you WANT it undamped in there, thats where the cancellations come from. That will change the math making it act like a longer tube. Fine if you tune it on the car, but it you just wing it like the video you may be too far out. It also dampens the reflection.

[@redlight3932]

That would ignite home boy

[@notamouse5630]

@@redlight3932 A tailpipe is full of CO2, CO, and trace unburnt hydrocarbons, the mix is less likely to combust than air. Also the steel wool could be made stainless or thick or be substituted with copper.

[@randr10]

I got that out of my system when I was younger. If it's something I drive a lot I want it as quiet as I can get it. I'll take a few hp hit by keeping it quiet and try to pick up performance elsewhere. I built basically a race car for the street years ago and when I was ripping that thing wide open throttle at 6 grand with the long tubes into turbo mufflers with side dumps, it sounded amazing. My buddy said it sounded like a NASCAR from the outside. The rest of the time that noise was the bane of my existence. I found myself not wanting to drive the car eventually because it bothered me so much.

[@atsernov]

Use the calculations as a rough guide, then use a slip tube to tune it to final length. It is impractical to try to guess or measure the correct values to plug into the calculator. There's a reason the drone is worse while driving than it is when the engine is revved to the same RPM in neutral. Also, if your resonator is a more complicated shape, you can tune out measurement error.

[@dwarrenwilliams9938]

I can only imagine the amount of cursing that was edited out when that crossmember got in the way 😂

[@JadXtreme]

Keep in mind that once you add the LSA, it may change the exhaust note again. I would expect it to have a similar tone, just louder

[@wailingalen]

Due I just came across your video. As a musician and car novice enthusiast, your video and the topics involved were the perfect intersection of science, cars and dyi! Greetings from F (Got a 23 Wrangler 3.6 with 6MT, just had an aFe muffler delete installed, and very content with the results, almost surprised, for how cheap it was

[@Akya2120]

You could potentially create an 1/8th or 1/16th wavelength Helmholtz resonator. Funny enough, when you only open one window in a car, you are doing the same thing. The cabin becomes a Helmholtz resonator.

[@leebarker539]

15:27: "um...pick my spot wisely." What a jewel of a moment. Thanks for the science and the smile.

[@BryanBeast13]

This is why you're one of my favorites. You're a technician you just don't change parts you explain and use your brain to fix things. Take care LT

[@LawrenceTolman]

much appreciated!

[@ryurc3033]

I have seen all kinds of factory exaust systems, .and modified plenty of them when I worked at an exhaust shop. Pipe diameter, length, thickness all effect sound, along with muffler design, where it exits on the vehicle(turn downs or straight). I even had a flat rectangle stainless tip that was 2 inches tall, and 10 inches wide make a weird ringing sound. I added a post inside the tip to make it not "ring" like a bell. You could hear a distinct tink tink as each cylinder fired on the engine. All I did was stabilize the walls of the tip and it completely eliminated the odd noise. Every system is different, thanks for experimenting some, gave me plenty of ideas. The turn down at the end bounces sound off of the ground and back into the truck

[@Finite-Tuning]

Yep, those damn tape measures always fall out of calibration at the worst possible time! Cheers 🍻

[@glynluff2595]

Between the wars and still occasionally seen in vintage racing some tuners had an 1/8 wave resonator attached to manifold to improve exhaust ejection and reduce muffler performance reduction.

[@jacobstevens5773]

Got to look out for a right spot to use the draggy. That was almost a different finish to the test drive with a Smokey Bear.

[@bobbystubblefield6723]

That exhaust sounds great, like the in-depth approach you took to get it right!

[@Wickhaven1]

On my Ram (it may help others) I took the extremely heavy factory muffler off, added on a single 10” circle track muffler and it sucked. I then put the factory resonator and single tail pipe back on. Nailed it. It sounds like an $800 exhaust and I got like $12 dollars into it..😁

[@grenadegoboom4967]

i bet your my neighbor

[@brandonbrandon749]

Finally some one who knows the exhaust struggle lord u can spend a lot of money and still not get what ur looking for glad u found a way to fix it

[@donthompson2188]

If you angle the aperture opening you will get a broader “Q” (bandwidth) with less amplitude. Nothing wrong with adding another resonator with a different length. Also what you ste working on is the standing wave between elements in the system. You can also add an expansion chamber between elements to eliminate the resonance as well. Since the speed of sound varies with temperature (density really) you might want to make a slide cap for the end so you can vary the length and tune it perfectly.

[@hectormartinez2255]

finally somebody that knows about safety equipment PPE,,,props to you sir,,,perfect example on how to be safe..

[@webbeddizzy]

I love that you are constantly making improvements to this exhaust system, trying what works and what doesn’t. I’m excited for the next iteration. Only critique I have about this edition is that you used a short radius bend rather than a long radius bend or sweep. I think that would allow the exhaust gases to flow better. Short radius bends cause more internal wall friction than long radius, which in turn reduced head pressure and flow. So possibly just a more gradual turn would help. I’m not sure if you mentioned any feeling of hp or torque lost do this resonator but I think a long bend couldn’t hurt.

[@johngalt97]

There is no 'flow' in the resonator tube which could be made 'better'.

[@randomguyontheinterweb]

Looks good. The mugen twin loop was my favorite exhaust, and it uses sound to cancel sound. Hytech also makes a twin loop design also

[@PetesGarageandperformance]

LT you are going to love the LSA supercharger. I have one on my 6.0 BMW swap and it’s amazing. I’ve also tuned a few trucks with the LSA swapped on and it really gives a “big block” feel with the instant torque. It would be nice if you didn’t need adapter plates though because they’re pretty restrictive. One truck I tuned had adapter plates with 317 heads. Then he put ls3 heads on and did away with the adapter plates. I had to add over 25% more fuel to the VE table in many areas because it was flowing so much more air. But this was on a 6.0.

[@LawrenceTolman]

Glad you had a good experience with the lsa, I’m pumped to get mine on.

[@justinkase1360]

Would be cool to see someone make an adjustable length resonator that changes to match any RPM.

[@drewdavis239]

Like, electric , automatic , servo.... i agree

[@Nicedesk]

The trombone style adjustable frequency tube sounds like an elegant but complex solution, heat and sliding metal sleeves of tubing might be a challenging build. Perhaps a series of butterfly valves inside the resonance tube would be simple and still provide an adequate range of cancellation? As each butterfly opens the resonant chamber gets longer. Also. waves travel through each other (think of ripples in a pond coming from opposing directions, and continuing past each other after the collide), but cancel when they arrive at a hard surface (exhaust tubing, or your eardrum) out of phase with each other. Maybe shifting the resonant frequency of the tubing (with exhaust clamps, or thick beads of weld) would reduce the drone. Thanks for taking the time to post that great video!

[@TheMrDarius]

This just goes to show everyone how much fun science really is.

[@rickybobby5950]

You got some skills! I learned a lot about exhaust science through your search for the perfect sound. Thanks!

[@thebrain9384]

Here's something I did that sounded beautiful. I had a kerker exhaust,4 into one. I pulled all the fiberglass baffling out of it and all it had was a big hollow pipe with a tube with a bunch of holes in it in the middle. Sounded pretty awesome, I could remove one nut and remove the muffler. 4into one straight pipe, awesome, sounded like thunder. I miss it.

[@erscustoms911]

My 05 4.8 van had 3” stock I just deleted the muffler, no resonance and definitely a noticeable difference in tone!! Ide have to say it’s deeper than your truck wot. On the other hand I could watch you weld up another 33 versions of your perfect setup lol ! your perfection is what I really like most ,and clean welds!!

[@varo2429]

My friend you are a true craftsman, congratulations

[@KurumaDesigns]

This is really cool and great info! Like others have said, a slip connection could be used to make an adjustable resonator to make it perfect without having to weld every time

[@vanhap]

Bravo I completely agree with you, we must upgrade our vehicles not downgrade them. If you wanted to tinker a little, rather than an additional pipe just remove the end you have already and make a handful varying lengths to slip over and test your normal day to day and see what sounds best. Great job i haven't messed with my exhaust since buying a K&N intake i bought years ago. That droned and drove me crazy so it was returned pronto.

[@jasonpavlik4904]

Yes! Do more videos like this. This was the complete opposite of the car part porn you used to do on TV.

[@petercarlson6721]

Thanks for the spead sheet and testing it all out on your truck... got an inline 6 diesel with a heavy drone and need some relief at highway speeds...

[@pixelpatter01]

Using radio antenna analogies your 1/4 wave trap should work. In radio you have to match 'impedance' values which is an analogy to pipe size. If a sound wave ( or a marching bunch of soldiers) were going down a hallway and suddenly came to a narrow spot or restriction you won't get a match. The tuned 1/4 stub may have to be the same diameter as the incoming pipe. I would also add a tunable plug at the end of the 1/4 stub. It would not have to be perfectly gas sealed just enough to reflect the sound. The plug could be tuned by connecting it to a threaded rod passing through a nut welded to the end of the stub. Tune for best results.

[@matthewdeluca9248]

Please don’t take it personally, but I would hate to be the poor s.o.b. working at the muffler shop when someone of your particularness shows up to get a system welded up…glad you are finally happy with the sound!

[@LawrenceTolman]

yeah, I wouldn't wanna work for me either lol. but I'm just glad I can do the work myself, because if I had to pay someone to redo it this many times, I'd go broke in a heartbeat

[@GlennPearsonDIY]

I'm in Eagle MTN, I drive that route frequently for my MPG tests for my channel. Nice job on the exhaust.

[@MarkLoves2Fly]

The resonance is not only tied to the length of the pipe, but also to the diameter. Varying diameter pipes will have different effects. I have a ton of experience with resonance, as a result of my time designing audio enclosures. It is possible to target multiple frequencies depending on your dimensions. This is a great video. My little car won't need this type of thing, but hey... it's fun to watch.

[@peterdarr383]

What are your thoughts of a butterfly that only opens at full-throttle but has a port for cruising-highway speeds ??

[@davelowets]

Yes, sir... Experience with building and tuning subwoofer enclosures will DEFINITELY get one going on the right track here.

[@creajohan57]

Cool! And if you want even more precision you could test quater pipe separate before welding it on the exaust. You can put a audio driver hooked to a tone generator near one of the pipe ends and then meassure the pressure at the other end, and plot it to see if your length calculation (since its bent) actually is precise/correct at 117 Hz. This way you know exactly from testing rather than from formulas.

[@Ianochez]

the low pass filtering in radio frequency can be made by a quarter wavelength wire, shorted to high impedance will result as an high pass or low pass filter.

[@billyvray]

Now to make an actuator-driven sliding resonator, so that at certain rpm it can lengthen or shorten to eliminate the drone where most driving is done.

[@grahamcharnock6453]

Congratulations, you just reinvented the wheel. Solo Performance Exhaust Systems have been around for years.

[@nizzan91]

Good stuff. Considering the ridiculous amount of variables in acoustics (temperature, cross section, material of the pipe, mounting, medium density etc.) you got really nice results.

[@juanguerrero2282]

Truck sounds great 👍, can't wait for the 6th exhaust system 😀

[@evanm3209]

I love simple stuff when you understand the science. Thank you very much!

[@banzaiib]

13:34 - holy cow, when you drop the gear and hit the right RPM range, the sound disappears. That's incredible!

[@PhoenixRising251]

Being a musician I totally get this. An RTA is a great tool.

[@Apachefog]

You could try putting an adjustable end cap on the resonator so you could fine tune the length to cancel the drone exactly where you want.

[@tptrsn]

Good stuff, can't wait to find out how the slightly longer resonator works!

[@flyonbyya]

Wish I’d known this 20 years ago with my Grand National. I had a 3”, 304 stainless single exhaust system made by ATR…high quality, but droned…AWEFUL !

[@TheMotoracer838]

I feel your pain, I used to do exhaust for a living, I too am really picky about exhaust sound. I might have mentioned before, when I built my sbc S10 Blazer it took 3 mufflers and a j pipe to get it where I liked it. On my j pipe I made it where I could adjust the length, didn't need the adjustability, it worked great from the start.

[@phillipherrera5]

I just learned a whole new concept. Thank you for your efforts.

[@HooniCoonCustoms]

I think there is a very important part missing in these calculations. Maybe I missed it when you were going over your spreadsheet, but in order for the sound wave to flow, the port size needs to be the total diameter of all Exhuast ports combined. So. The tuning muffler needs to be the size of your Exhuast ports in inches *πR Squared. Then the length of the line is the speed of sound ÷ target frequency. Take that total divide it by 4. Multiply the answer x12 to get it in inches.. then if you would like to create a vacuum at the end of the line, add a single horn shaped outlet pipe going from line size to at least .20% larger. This will increase the speed the Exhuast leaves the line by increasing the amplitude of the wave

[@MarkWesche-hj4dm]

I don't think .20% will make much of a difference in anything

[@MrKnutriis]

Great video and explanation. Luckily, they sell exhaust systems to solve all this with all the welding and engineering built right in.

[@Roland_Rohrle]

Interesting. Good to see you wearing safety gear and using a guard on your grinder, plus tight fitting gloves. Nice work 👍🏻😎

[@AaronSchwarz42]

Exhaust gas velocity has an effect on the sound because of the amount of exhaust gas exiting the engine, which scales with RPM & throttle position. A larger pipe diameter effectively builds a musical instrument & lowers gas velocity (which you correctly deduced was caused by the "4 inch" pipe If you study how Yamaha works with Toyota to make "quiet" exhaust, you will notice they never use large diameter exhaust tubing on smaller light duty vehicle engines with smaller displacement engines. Effectively, the exhaust system & engine type & displacement all have to be matched correctly. Doing harmonic canceling can be achieve with an electrical noise canceling system called active noice canceling - if you want to really reduce the exhaust noise. Getting better performance (tires, suspension, engine tuning, head porting & texturing, more powerful ignition, boost pressure, better lubrication, enhanced cooling), improving the aerodynamics & mass reduction / lowering (lifting or raising vehicle creates turbulence & drag underneath that reduces performance & wastes energy, which decreases fuel economy or wastes your gas money faster. Good for keeping catalytic converters, those make the exhaust less toxic & make it smell nicer as a result! By converting toxic oxides of nitrogen to nitrogen & oxygen, the cat helps keep the air near the ground where people are breathing, cleaner !

[@outinthebackyard7579]

That is also called a hermoltz resonator and I have wondered for years why people don’t use them. Hopefully your influence will make them more popular.

[@carlhayes-ze5nd]

I wonder if ported speaker science would help with the measurements of the tube? Instead of increasing output at frequencies you would be decreasing output or canceling. I’d imagine similar acoustic science is happening here. More than likely the angle of that tube does not matter. It could be hidden from sight rather than parallel to the muffler? This is a really cool idea!

[@mrc4912]

Cabin drone at highway speeds is really annoying but it can be a killer, too. One car I had with this trait used to almost put me to sleep when I was driving on a long trip. I finally put an exhaust tip that had a large nickel spring that opened up as the throttle opened and it 'tamed' the sound while continuing to provide the full power of my Borla muffler.

[@alexsamson9942]

Great info! This must be why some cars lull me to sleep while some others dont.

[@mcmillan1963]

Manufacturers, GM for example. Have been using rubber mounted exhaust weights for many years. Especially on like V6 applications. This vibration cancelation is effective in removing vibration and droan across the board.

[@rustywater3219]

It also doesn't need to be full pipe diameter. You're not flowing air, just letting pressure waves move through the air in the side branch. Corsa mufflers use this concept and have tiny slits in the center tube. I think magnaflow has a new setup with 1/4 branch resonators, maybe just for mustangs though. If you're handy enough, you can make a slide pipe for the end to make it adjustable to dial in the frequencies to cancel.

[@RideGasGas]

Stubs are used a lot in radio frequency circuit design, and their specific length 1/4 wave, 1/2 wave, and open or shorted (as in your application) change the characteristics. If you really wanted to geek out, I could see an application where a microcontroller like an Arduino or similar is connected to a stepper motor that adjusts the length of the shorted stub on the fly for conditions, eg, temperature and RPM.

[@shoominati23]

I think an auto magazine of some description did a test on resonators a long time back, but not these kind of resonators - The resonators on inlets before the throttle body on inline 4 cylinder engines. They removed the little rubber chamber that attached to the inlet tube just before the throttle body and experimented on a dyno with various shapes and sizes of resonators from different cars. You probably would not believe this without seeing it - and I no longer have the magazine for proof, but over 3 horsepower was gained with the best resonator they tested. And the winning resonator was? a 500ml coke bottle attached to the manifold.

[@goptools]

Hi LT, Interesting math calculations. Kind of like figuring out the optimal length for a quarter wave antenna for radio reception at a particular frequency. Glad you got the drone down to an acceptable level. It must have really been driving you crazy to go through all the exhaust iterations. Thanks for the video! -mike

[@garybates5784]

I've got Solo J pipes on my G8 Gt instead of the mufflers. Work flawless

[@dannyflood3291]

Gm puts those on the stock intakes to reduce intake drone too, but usually you only hear that under full throttle

[@NXT_LVL]

The newer magnum motors had the tone box that was between the air filter box and the throttle body. Same principle. Apparently it’s to quite it down. Though I was always told they heard the whine on the V8 and the intake from a 1/4 mile away lol

[@TheNumbers400]

Looking forward to the LSA swap. Hope to see a ton of tuning notes. I am installing a LSA on a 6.0 in a Ranger on 46" MT´s

[@fm9572]

Most intake plumbing on newer vehicles have these in the plumbing before the throttle body, to reduce the sound of air entering the intake.

[@Worthrhetime]

You have some amazing welding skills. 😊

[@taoisttiger4702]

Cool video I might try making an adjustable one eventually and base the initial design on your spreadsheet! Thanks for the video and data.

[@myturkishlife1777]

I fitted one of these to my girlfriend, works a treat no more droning 😁 Have a great day everyone 👍

[@kennethperian4370]

Great job showing and telling, I am rebuilding my 460 in my truck f350 1990 . Putting header on it so I may do that to my truck. So thanks for telling showing see ya next time see ya bye.

[@Guyver2099]

Don’t feel bad with so many variations of exhaust. Was a guy at an auto hobby shop. Spent like a month (afternoons and weekends) building a 454. Then spent most of a year building a rebuilding the exhaust. Once done it was smooth and beautiful sounding. Also let out a shock wave that hit harder then a concussive grenade. Was absolutely amazing.

[@ame7165]

i completely understand on the drone thing. a TON of car guys swear it doesn't bother them, but i think they're lying to themselves. take a 2+ hour road trip and i think they'd not enjoy it so much. i had a bmw m2 and it had the optional factory installed "m-performance exhaust". it has a wireless remote that goes in your cupholder that opens and closes the exhaust valves. that car with the manual transmission DRONES LIKE HELL. i flew from the midwest to new jersey to buy the car and drive it home because it was the exact color and spec i wanted. i was ready to blow my brains out after an hour. i had like 20 hours to endure. i drove in 5th gear, i tried windows down. everythign i did only helped a tiny bit. mostly just changed the tone a hair, but it was just always droning. but it drones soooooo badly. my head was pounding with a migrane the whole two days. i had to drop halfway in ohio and sleep. it was that bad. what makes it worse in that car, due to being turbo, the exhaust in stock form isn't super loud (but sounds really good), so they add sound through the sound system. those come with really good systems, and unfortunately, even in 6th gear with cruise control on, the fake sound never stops, and so the freakin subwoofer also drones. not even joking. so imagine bad exhaust drone AND speaker drone. the next morning after arriving home i called the local dealership and asked them if they have stock exhaust laying around and if so, if they'd swap it and i'd pay labor. they did and i agreed. i literally paid them to put stock exhaust on and let them keep the expensive upgrade exhaust. then i bought a wiring harness that bypasses the ASD (the crap that adds fake sound to the speakers). oh and to make things worse, the car had continentals. being a northeast car, it came with the all season continentals and if anybody hasn't had those, after several thousand miles of wear, they start to drone badly. not kidding. so that also contributed. i swapped them for michelin pilot super sports and finally after all three of those things, the drone was 100% gone. but the car sounded amazing regardless, so it was a win-win, and the next owner really lucked out in that regard. my friends thought i was crazy, but damn, when i was commuting for an hour each direction to work, i want to hear my music, not arrive at work with a migraine every day. very cool video, and nice work! i'm glad to see i'm not the only one particular about exhaust drone

[@RobWhittlestone]

Don't forget that the speed of sound in a gas varies with the density of the gas which itself is temperature dependent. Long story short: make your measurements/experiments when the engine and exhaust is up to temperature for optimal results. That is some VERY NICE WELDING! GREAT WORK, GOOD RESULT!

[@LawrenceTolman]

great point, and thanks!

[@kevinfrye1822]

We put a few exhaust system on at the shop that come with quarter resonators in place of the mufflers for the straight pipe systems for the Dodger chargers and challenges. There actually adjustable the j pipe has a second pipe that slides back and forth in the j pipe with a band clamp.

[@BudKash]

Seems to me there's a much simpler way to find the precise length required to cancel the problem frequency range, and that's to use a slip joint using two slightly different diameter pipes that fit relatively tight, one inside the other. You could tack weld or put a set screw on it to make it field adjustable until satisfied with the result, then weld er up.

[@BradleyGibbs]

As someone who commutes on a 250cc motorcycle, hearing you talk about driving around at my idle RPM is really amusing...

[@N4CR]

Thanks for finally showing the muppets how to do it. Most people delete them then complain about drone lmao. Here is an esoteric exhaust tip for you, build your resonator 2x engine capacity. Then it isolates the rest of the exhaust from causing back reflections or weird restrictive issues by providing a large buffer basically. So you can do stupid BS after that with routing if necessary, or a restricted exhaust output etc.

[@knucklestheechidna5718]

Lol I had a Geo prism that I cut the muffler off of and put a cherry bomb on it. I messed up the transmission and 5th and reverse wouldn't work so I would always have to cruise down the highway in 4th and Flintstone out of parking spots. That thing had such a bad drone but I'm a weirdo so I actually enjoyed it and it was good reassurance that the motor was still running and keeping me company late on the highway alone.

[@FFE-js2zp]

Seems like you could put a conical end cap to distribute the dampened freqs.

[@longdarkrideatnight]

You could even make it remotely tuneable if you added a moving end stop, you could even add an actuator you could make it tunable from the cab, or under computer control.

[@louvendran7273]

Thank you very for such an articulate, well researched, informative and factuality correct presentation. I'm really grateful to learn so much.

[@LawrenceTolman]

Glad you enjoyed it!