Suggestions for muscle car sound muffler without drone

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Guys. Hands down the best muffler for muscle cars without drone is the Heartthrob HVS muffler. I have one on my 99 z28. These cars are known for drone in 6th gear. My car doesn't drone at all. Plus it has a great sound. It puts 420 hp to the ground. My duster will get pair of these when the time comes to put exhaust on it.
 
How can I upload the video from my phone? I logged on through the forum runner, but it will only accept a photo? Can I send it to someone to have them upload it?
 
I just figured it out. I put it on YouTube. It doesn't sound as good though. It will give you a good idea of what the Heartthrob muffler sounds like though. Here's the link: Hi Jessie

[ame="http://www.youtube.com/watch?v=EA-xsoI3MkI"]Video from My Phone - YouTube[/ame]
 
On my duster I don't have any drone , I have summit racing long tube headers, summit racing 2.5" dual exhaust from the headers all the way back, I have thrush welded mufflers (basically a flowmaster 40 series), and I have Gibson wide mouth tips ( 8" over all length, 5" of which is the tip length, by 2.75" tall by 6" wide, slant cut, single wall, offset inlets for both left and right tips due to my springs having a relocation kit and having to run my exhausting the outside of my leafs. The offset inlets make the exhaust appear to exit in the factory location. Here's a video I just took the other day ( was running a little rich in the vid, I have since did some float adjustments and retuned the carb ). Hope this helps those who might me interested in this particular sound. I love it

[ame="http://www.youtube.com/watch?v=tzIndK7cUTQ&feature=youtube_gdata_player"]New exhaust tips on my 72 Plymouth duster MOPAR - YouTube[/ame]
 
So three chamber performance muffs, Magnaflows and Dynomax Turbos drone at different levels of bad. A muffler that doesn't drone is an easier fix than resonator tubes.

Dynomax Turbos are on the car now and if I'm not happy with them Dynomax will pay me what they cost me plus have UPS pick them up at my door. The same 90 day not happy with the muffs applies to the VT's too so it's worth the risk. So with that option I talked to Dynomax and started the process. After reading more about the Dynomax VT muffs, on a site that installed them and explained their operation, I decided to go with them. They are ordered and will be here this week. After I get them and remove the turbos I just have to email a copy of both receipts to Dynomax.

What I read said the chamber part in the VT's is a resonator for the low frequency drone and works even when the valve is open. The perferated pipe part is for the high frequencies. I understand this valve system is being used on production cars. We'll see how good it works.
 
Update:

Uninstalled the super tufbo's and installed the VT's this morning. Going to test the new Dynomax VT's in the morning. I'll try and post some sound clips or video. I have sound clips of the other muffs too.
 
I couldn't really record the drone well enough to show the ear rattling sound of it. But the frequency/db graphs really shows it. Here's the graphs of the three mufflers. I also tried to attach a link to the sound files since I didn't see how to upload them to the board. Seems to get you there ok.

https://skydrive.live.com/redir.asp...!Arc6lHkCbTR02K4&Bpub=SDX.SkyDrive&Bsrc=Share

The first image is the Dynomax Super Turbo, second image is the Dynmax VT and the last on is the Magnaflow. The drone is the big spike. The drone sounds significantly lower with the VT's. Still there but a lot lower and not ear rattling. Probably close to what it was with the stock mufflers but these have much better flow. Looking at the graphs it's ~12-14db lower.

After driving the car some more with the new mufflers it's a decent solution. The level of the drone is a fraction of what it was so it's not bad now. I choose this as an easier solution to the drone but I think the resonator tubes would have probably kill the drone but they are not as easy as swaping mufflers.
 

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jimjimjimmy said:
i have dyno max 3'' on my car and only after 2000 miles the baffels are rattiling that bad i dont even want to drive it sounds like **** and is hard on the head when driveing. other than that when new they sounded good with no or little drone.
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buck351 said:
Do you have the Dynomax VT? If so I was concerned about them rattling. Moving parts in a muffler worries me. Someone posted a reply he got from Dynamax about the VT rattling in another thread. Then said you need to have a cross connection to avoid it.
Click to expand...

jimjimjimmy said:
i will check tonite to see which ones i have and i do run a cross connection
Click to expand...
sorry for the late response but i have the 172221 ultra flows did anyone here ever do any surgury on these mufflers. im considering doing a little surgury to see if i can fix the rattleing .and sometimes it sounds like its chokeing flow off also
 
Update:

I replaced the valley cover since I had a small oil leak. I thought the exhaust got louder after replacing the valley cover. I decided to try not cutting out the opening in the metal valley cover for the exhaust crossover for the intake manifold. I'm surprised how much louder the exhaust got. I put a different carb on but it's still a Carter and the same cfm. Only difference is not cutting out the valley cover for the exhaust crossover. I've run the car for years with the heat riser full open without any problems so I thought I'd try leaving the crossover blocked off. It's made a noticeable difference. There's a gasket glued to the valley cover for the intake so I should be able to just unbolt it and dremel out the metal valley cover for the crossover. Note the difference in db level for the drone spike! First photo is with the crossover open and second is with it close.
 

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Well I'm not sure the crossover carb heat really effect it or not. I ran the Dymomax VT mufflers for most of the summer last year. Drone was reduce as you saw above and it was a nice level, not too loud, for the regular driving. all in all it was good. Well they have gotten louder this summer with no other changes. General level is up and the drone is louder than it was last summer. I did a search on line and others reported increases in the sound level after several months of driving with the Dynomax VT mufflers. Now it's too loud including the drone. So much for dynomax VT mufflers. Not sure why my guess would be changes in the valve and/or the fiberglass like material they used in part of the muffler design.

I don't think mufflers should increase in sound level in such a short period of time. Magnaflow uses stainless steel wool instead of a fiberglass like material. I wonder if this is why.
 
Seen Magnaflows blow packing out as well. We used to use a 2" hole saw on the case. Pull out the dead packing. Head down to the dollar store,buy a few packs on stainless steel pot scrubbers. Packed them in,made a tin cover. Mounted the cover,red hi temp RTV and self tapping screws.
 
So today I took a vacation day to work on the dart exhaust. I spent like 7-8 hours on this project. I finished fabricating and installing the branch resonators which are 1.5" diameter pipe tuned to 125hz. The tail pipes are 2" diameter. The drone is complete gone. In fact they even quieted the complete exhaust system down. I currently have the Dynomax VT installed and from the post above you can see I tried a number of other mufflers. Considering how extremely well these resonators work I could put the Magnaflows back in if I want. The resonators do absolutely nothing to the flow just the sound. They work GREAT. I installed one on each tail pipe at the point where the pipe come down after they go over the rear axel. I installed them with a saddle connection over a drilled hole in the pipe so the can be easily removed and to avoid having a stub on the tail pipes which would make their removal harder. The clamp connection at the 90 gave me 1" of length adjustment if I needed it. Even though I understand the science behind these I was amazed how well they worked.

After thinking about the results I believe I know why the resonators effected the drone and the overall sound. The mufflers create a low frequency tone to the exhaust system which would be more effected by something tuned to a low frequency. Some mufflers have more high frequencies in their design than the Dynomax mufflers.

Update:
After driving the car more I am enjoying no drone and quiter exhuast without restricing the flow. It may be too quite for some but I can listen to music/radio and I don't get tired of the exhaust. The exhaust before the change was fun for about 5 minutes of driving. Now it's actually fun to drive for longer peroids of time and you don't atract as much attention. FYI most of the black section of pipe isn't even hot.

For those who want more information on making branch resonators here's what I did. You have to first know the frequency of the drone. You can calculated it but I just measured it with an app for my Andriod phone called FrequenSee - Spectrum Analyzer. Then instead of using an equation to calculate the size of length of the pipe I used this site http://www.diracdelta.co.uk/science/...be/source.html . Using this site you can plug in dimensions and calculate the resonant frequency until you get what you want. The site also shows you a nice graph of the db verses frequency for the resonate frequencies. You have to have a flat capped end on the end of the resonator tube. It won't work if you crimp it down and weld it. A muffler shop tried that for a guy and it didnt' work.
 

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I wonder if an H pipe would have helped since the plugging the tiny heat cross over created a spike in the drone.
 
A crossover may have helped. The Dynomax VT's helped to lower the level of the drone 12db but the branch resonator totally eliminated the drone frequency. I've read of cars with crossover pipes droning. There seems to be a number of factors that can affect drone. Apparantly from what I have read it boils down to if the engine and exhuast system create a frequency that is at the resonate frequency of the tail pipes that act like a pipes on a pipe organ.
 
I used to compete in SPL competitions and we tried to tune our ported boxes to the resonant frequency of the vehicle we were using. Easier said than done sometimes.
 
Incase anyone would like to see the plot after the side branch resonators see below. It's difficult to keep all the conditions the same for the data. It may not have been taken on the same road area but it was done with the windows down and going up an incline like the rest of the plots. Different road noise levels can bias the plot up or down compared to the others but you can see how the peak of the drone has been cut down. As I noted to your ears it's gone.
 

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Your thread and your travels are very interesting. Up until now I have never seen anything regarding these pipes. I don't get much from youtube videos because it's coming from little speakers and the person recording always quickly revs the engine up and down. That IS NOT the problem. The problem is a constant RPM while you drive where that resonance gathers and grows and makes you feel numb. Now for a few questions.

I assume the length of the 90 was also calculated into the overall length of the pipe?

The graphs you're showing, is that from the phone app and the screen on your phone? I see one shows Samsung in the corner so I guess it is.

Looking at the plot, I see the spike and from reading your post, I gather that that is the peak resonance. So when tuning the pipe, that's where you came up with 125hz as the target to tune to. Am I following this correctly so far?

You went with a smaller diameter pipe and it worked. Based on that it's the length that's important because the length is what controls the return time of the sound waves within the exhaust system, did your research show at what point the smaller diameter of the resonator pipe might negate it's ability to perform it's function?
How did you determine that a smaller pipe would still work?
Does a smaller diameter pipe factor into the length equation? I would assume not because we're dealing with the distance the waves travel and not the volume. But would too small a resonator pipe not have the desired effect on the larger mass of exhaust flowing by it? I'm wondering if a 1.5" pipe would work still on a 2.5" exhaust system? The smaller diameter pipe is certainly desirable as far as fit and discretion.

Thanks for sharing.
 
Downloaded the app. That is just way too cool. Now to go to for a ride up that hill on the way home that brings out the drone at it worst.
 
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