using SCIENCE to ELIMINATE exhaust drone: I FINALLY did it!
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- เผยแพร่เมื่อ 15 พ.ค. 2024
- I know, I know! You guys are probably getting sick of seeing exhaust builds on the GMT800 Stepside build, but this cammed 4.8 LR4 is kinda annoying do drive when the exhaust drones, and I'm bound and determined to defeat this issue once and for all, while maintaining 4" exhaust. After exhaust version 4, we have the overall volume to an acceptable level, but the resonance and drone were killer, so with a little help from science and a quarter wave resonator, we're gonna tackle this issue head on.
#exhaust #resonator #magnaflow
0:00 What is a Quarter Wave Resonator
4:08 Building the Resonator
7:27 Fabrication Notes
10:00 Oops...
12:05 Test Drive
15:05 0-60 Testing
17:39 In Depth Calculations - ยานยนต์และพาหนะ
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.
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!!
Yeah man thank god I don’t think we could have taken another video about the same thing again.
Lol passing the cop was great, and that resonator made a difference!! Good work man!!
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.
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.
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.
great info I didn't even consider!
Now that’s science !
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?
@@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.
@@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.
Make the resonator so it can slide like a trombone. (Slightly larger pipe over slightly narrow pipe). Then you can tune it in. The drone is also likely to shift some with other mods. Once happy make the final version.
I've seen systems set up like that. But how about a system that had slider controlled by electric motor, which was controlled by frequency measuring device inside cab and would adjust itself automatically. Best of all worlds this way, totally automatic and no drone at any rpm's!!!! Here's a million dollar business idea for you LT. ;-)
@@ChevySS1968 not too hard you can do it with a raspberry pi (possibly an Arduino if there is audio spectrum analyzer hardware for it) and a linear actuator (or possibly steeper motors) the issue is without clamping it in place it's hard to prevent exhaust leaks.
@@Avi8tor857 - Joe, I actually considered the leaking, and I agree. But I believe it 'might' be solvable with precise fitments at the sliders. I mean, if they can seal up a Rotary engine's insane configuration, then they can surely seal two sliding pipes. Dave F.
First thing I thought of when you mentioned lengths. Trombone player here. I really like Chevyss1968's idea!
Attach trombone to actuator with controller and input mic to chase down resonate frequency
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!
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.
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 ....😎] ..
isnt this a quarter wave resonator? or does this design work in both ways?
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.
he made a standard muffler the most complicated way possible.
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.
Do you mean a 45 degree end, at the end of the resonator tip?
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.
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.
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...
Have you ever done one on a V6?
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.
@@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.
Pure Genius.! Compliments from a retired mechanic, age 64, former Navy engineer, drag racer. I need to hear my engine at extreme RPM, not the exhaust.
I really appreciated this series of videos. Love exhaust tuning theory / practice & your honesty with trial and error was great!
This is pretty cool, man. I've always thought about doing this to an exhaust but never had the need. Nice to see you prove out the theory.
I think you win the award for messing with an exhaust. And i felt it in my chest when the exhaust hit your cross members, but glad you figured it out.
I love all the combos that we are seeing. I really appreciate the technology being used to prove the reality of the concepts.
You got some skills! I learned a lot about exhaust science through your search for the perfect sound. Thanks!
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.
People tends to use smaller pipe just for the clearance haha.
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.
How do you adjust for size? I have 3" but can only fit a 2.5 " j pipe
@@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.
Make an 9x11x17 inch can with the through holes at your 4" diameter but offset to one side on the input and dead center on the output then run a set of 4.5 inch holes through 9 baffles that are spaced progressively tighter towards the rear in the line from the input to the output. You'll enjoy the results, doesn't need to be perfect. It can go after your rear muffler with a dumb tip on it. Mid 90's I was playing around with ways to reduce the shock-pulse of the exhaust of aircraft engines on air-boats and came across this design - it is mathematically a nautilus first derivative.
IM a bit odd and can never visualize things without seeing them, this confused the hell out of me BUT i am addicted to custom exhaust notes on my cars so they sound like no1 elses. My local exhaust man is a good friend which makes it easy. Im always getting him to do funky shit lol
Can you link me to some sort of diagram pls as im interested in this,
Cheers
That sounds so novel. I'd be very interested in a picture of it too. I think I can picture it correctly myself but I'm not 100% on it. If you could upload a rough sketch to imgur or something then that would rule.
Its a oval muffler can. 9 perpindicular plates inside like bulkheads in a boat. One hole in each "bulk head" 4.5" each. intake hole is centered. exhaust hole is on offset. Plates get progressivly closer towards the exhaust side. Use fibinotichi caculation to space the bulk heads if you want it perfect like a natulus. I have no idea if this would work universaly ,but it could.
Im assuming dummy tip refers to a cap on one end? But im not 100%
Was always intrigued by these after seeing a few guys do them and report good results. Thanks for another great video!
That exhaust sounds great, like the in-depth approach you took to get it right!
May I suggest an adjustable resonator. Similar to a trombone slide. Fully tunable an adjustable
This is what I'm planning. Make it adjustable, and then weld it where I like it after testing.
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
@@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" .
@@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. TH-cam to learn the programming.
@@NitroNuggetTV stepper motor and an arduino and bam,,,i could code it.
Hey LT, great video on quarter wave stuff!! Great concept and setting it up etc. I was wondering maybe if you can show a clip on how you did your settings up before you start to tig weld etc, kind of show us how the tig is set when you start to weld, thought I'd mention that. Great video overall! Love it! Many thumbs up!!
I love simple stuff when you understand the science. Thank you very much!
I just learned a whole new concept. Thank you for your efforts.
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
Persistence pays off LT , I’m glad you got it the way you wanted it 👍😀 great job and nice work
thanks! it was a long journey to get there, but I'm glad it worked out in the end
Good stuff, can't wait to find out how the slightly longer resonator works!
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...
I definitely love the video without music. Very soothing hearing you work
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
Like a trombone 😆
@@johnrodrigues2018 precisely
Seems legit
Absolutely would work.
you beat me to it , some adjustment takes out the variables in the temperature calculations
Awesome video LT. Thanks for breaking down the science of noise canceling.
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
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!
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.
@@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.
@@1stAxelKainhow’d you manage to make it adjustable?
@@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.
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.
If not done correctly you can get noise back/added. Done with all the calculations - adding a cancelation wave at the correct frequency - works.
Cool video I might try making an adjustable one eventually and base the initial design on your spreadsheet! Thanks for the video and data.
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
Tip: Pack some steel wool gently at the end and pin it to broaden the anti-resonance and damp more drone frequencies.
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.
That would ignite home boy
@@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.
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
Great work, thanks for showing the steps!
Man,, this is so relevant... Good on you for having awesome content... Been following you since Truck Tech and gotta say that was one of the most fulfilling and information packed car shows out there,, you were a perfect pick for it... Keep it up bro
I appreciate that!
You remind me of my old days when I cut off my exhaust system and would drive around at exact RPMs so that it wasn't obnoxious xD I had such a small window I swear there was like a 100 rpm band to keep it in or else it would be sooo obnoxious.
You are absolutely right, the large 4" exhaust is the primary reason behind the drone. Too bad you have fancy muffler tips, if you had a normal exhaust pipe coming out the end you could easily temporarily slip on a reducer or downturn or reducer + downturn combination just to see how it sounded because I'm sure it would make a huge difference.
To understand why the size of the pipe makes such a big difference in drone, if you make an annoying droning sound with your voice and open and close your mouth from wide open to barely open, you will instantly understand what is going on with your vehicle exhaust. When your mouth is wide open, it's like the room you are in is part of the resonant chamber. You are basically INSIDE and not separated from the noise generation. Once your mouth is small most of the noise gets captured inside and resonates inside of your mouth, and the room your in will be much more quiet, because now there is a separation between the source of the sound and the room you are in. It's exactly the same with exhaust. When you have a 4" exhaust, it's essentially like living inside of the engine. There is nothing separating you from its sound, you have become part of the sound chamber. Now when you reduce the muffler exit size, a lot of the sound starts reflecting back up into the system which captures it and creates a separation so that now you are no longer INSIDE the sound chamber, you are outside of it. And once you are outside of any sound chamber compared to inside of it, the difference in drone will be huge. That is essentially what drone is, being inside of a sound chamber that resonates.
And let me tell you, if you put a reducer on the end of your exhaust pipe to go from 4" to 3", I bet it would be hard to even notice a difference on a dyno. But it would make a huge difference to your ears. If you could easily slip them on and off with clamps it would be fun to try different sizes for science. If you reduced the end from 4" to 2.5" or even 2" the drone reduction would be so incredible it might be hard for you to believe. The ideal situation in my opinion is having a cut out so that you can have a nice quiet system for normal driving, but if you want 100% no restrictions maximum performance to put the hammer down, you can open the cutouts. That way it's quiet the majority of the time, and the tiny fraction of the time that you want maximum power you can have it too without annoying everybody's ears all of the time including your own.
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.
I used to watch you back in the day on powernation and found you on TH-cam. Love the content and would like to see more hpt stuff myself as I use hpt myself and like to see how people do things differently to achieve the same result.
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.
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.
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.
Awesome information. Glad to see all the hard work paying off! Well done
Much appreciated!
Glad to see another Utah dude! awesome truck and sounds cool too! I'm getting ready to swap my efi 460 into my dentside, and I'm day dreaming my exhaust, this helps me a lot! thanks!
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.
I was going to post the same thing, but checked to see if anyone else posted the same idea ;)
Like a rusty trombone
Not sure if it applies here but as a loudspeaker designer, if you increased the diameter of the pipe it would effectively double the length of the pipe at the same wavelength. For example: @2" I.D. x 28", or @3" I.D. x 56", and so on. This is strictly for tuning a specific port frequency and there is no hard and fast resolution because it is alignment dependent. Cool video!! I've never seen science like this applied to an exhaust. I'm glad I was able to learn something different.
I have read in books about exhaust systems that widening the pipe in exhaust applications does not alter the resonant frequency, but lowers the Q- broadening the frequency band over which it has an appreciable effect. Still probably favorable.
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.
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!
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.
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.
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.
15:27: "um...pick my spot wisely." What a jewel of a moment. Thanks for the science and the smile.
I built a pair of these for my 04 Titan after header install. Worked amazingly well!
Love doing ham radio. Also love finding something completely different, that still follows the same laws of physics. Great video.
I had the same thought, like an exhaust j-pole.
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.
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
Great video and super quality build. I've been researching these Helmholtz resonators lately. I'm going to make one that's adjustable in length.
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
much appreciated!
I’m glad I saw this. I knew it could be done because Volvo does it and I think the s2000 has it as well. I never knew the maths behind it. Now I do.
Thanks
😮 thanks for sharing your experience!
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
Have you thought about using a sound deadening material in the cab? Boom mat? Etc?
Mufflers with the correct baffles work, its why my stock truck doesn't make alot of noise.
That kind of insulation typically only works in the mid to high frequencies. The lower the frequency, the more difficult it is to deaden.
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.
Hey mate, thanks for the video helped heaps! solved drone on a straight through Cat deleted 05 3L V6 Camry. Your spread sheet was spot on!!
An old man at the drag strip had a 10 second Camaro with a SBC 400 and nitrous. He had long headers, collectors with an "H" pipe, then 2" exhaust the full length to 2 glasspacks under the bumper, but these glasspacks were WELDED SHUT. There was another "H" pipe near the rear axle which emptied in the middle to 2 MORE pipes and glasspacks and 2 exhaust tips.
So the sound "shock wave" traveled the length of the car, had 2 or more opportunities to diverge, passed thru the sealed glasspacks TWICE, got reflected straight towards the engine, and the noise finally had to go thru ANOTHER glasspack to be heard. It was surprisingly mellow and had a nice rip on launch.
Yep, those damn tape measures always fall out of calibration at the worst possible time! Cheers 🍻
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.
There is no 'flow' in the resonator tube which could be made 'better'.
im so glad you figured this out all on your own and no one recommended this exact thing to you 5 videos ago.
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
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.
I put a pair of these (I call them quarter-wave attenuators) on my Mustang Cobra back in the day. I was amazed at the difference. With 3.73s and Flowmaster mufflers, the drone on the freeway was terrible. The attenuators reduced the sound energy by about 6db with no loss of performance. When I sold my modified H-pipe years later, the guy didn't understand my explanation. He cut them off, lol. You glossed over it. But temperature has a big effect on wavelength. I assumed 200 degrees F, and it worked pretty well. When it was cold, sure enough it was louder, but quieted down after a couple of minutes.
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..😁
i bet your my neighbor
Great video! I appreciate your logical and methodical approach to the problem.
Glad it was helpful!
Very clean work, i like the paint over the welds.
Would be cool to see someone make an adjustable length resonator that changes to match any RPM.
Like, electric , automatic , servo.... i agree
Yes! Do more videos like this. This was the complete opposite of the car part porn you used to do on TV.
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
Thats why I enjoy Loud Valves, you build a quiet exhaust and when you are wanting to play either by using boost or vacume to open the valve it will automatically become a beast. After the pull it acts like a normal truck
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
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
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!
Truck sounds great 👍, can't wait for the 6th exhaust system 😀
Thank You. I needed this information badly.
This was an excellent video. Nicely done!
Thank you very much!
Interesting topic and great video. I like that vice. Thanks!!
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.
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.
Nice vid, thanks. Exhaust drone is one of my most hated things. Really gotta use variation of the old carpenters adage on this one, "calculate twice, fabricate once". Heck, I'd be calculating a dozen times prior to fabricating. That math is damn tricky!
That's to cool thanks for the info!!!! I've aways thought you just had to deal with it .
You could also add a 2nd 1/4-wave trap at the shorter length and the effect would be additive. Should be placed at the same distrance from the engine, i.e. drill the hole across the pipie from your first drilled hole. And as several others pointed out, you can make an adjustable cap to fine-tune the response. A larger diameter pipe will have a more broad bandwidth, but I dont think you need that.
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!!
I love anything that has to do with tuning an exhaust system! Good job LT!
Thanks! 👍
In rf engineering we use “stubs” on PCB’s to change the impedance of circuits. They are essentially the same principle. Usually the stubs are radial stubs and occasionally they are split into two parts and effectively make up a bow tie shape. The progressive change in width makes it so they affect a larger range of frequencies. I bet you could do something similar and affect a wider range by introducing increasingly larger width in the resonator:)
Thanks 🙏 for the heads up on drone.
No problem 👍
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.
This is good content indeed. Thanks mate 👌
Very cool! Great video!
It'd be fun to make it sliding with a stepper motor and threaded rod actuator. Then you could have it adjust based on RPM.
I'm guessing loosely packing the resonator with fiberglass would help. In subwoofers, that helps A LOT.
Were it mine, I'd have poured all that time into treating the interior with ResoNix (or a lower end alternative like Dynamat or Second Skin). To be fair, stereo comes first, exhaust comes second in my world. Still, I have to admire your relentless fire for getting that exhaust just right. I love that fact that you dove into the physics of sound and made this happen. Usually it's just us audio nuts that worry about all of this for port tuning sub boxes etc. haha!
finally somebody that knows about safety equipment PPE,,,props to you sir,,,perfect example on how to be safe..
Always love seeing the welds
Great job , and enjoyable contents .
Thank you very for such an articulate, well researched, informative and factuality correct presentation. I'm really grateful to learn so much.
Glad you enjoyed it!