Trying to Eliminate Drone. Need Another Opinion.

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MuuMuu101

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So, I have this long thread on Moparts on trying to reduce the drone in my car. 408 stroker making 500 + hp. I have TTI step headers with a 2.5" X-pipe system from TTI. My drone was between 1500-2200 rpm.

To some up my journey so far, I bought some dynamat and put it on the rear panel and it helped a little bit. Then I removed the 14" long Dynomax mufflers and had 18" Magnaflows installed as they were the largest I could go and that quieted the car down (great), and reduced the drone down to 1800-2000 rpm. The guy who installed my exhaust didn't want to do anything else. After that, I noticed my driver's header was resting on my PS box so I shimmed the engine so it wouldn't contact and that reduced some of the vibration in the car.

I'm kind of stuck at this point. There's no room in front of the mufflers to add resonators as the exhaust pipe centerline is only 2" away from the bottom of the car. So, that leaves me to the rear of the car, past the mufflers, and I don't really have much room to add anything back there unless I get crafty.

I don't have any welding ability so no Helmholtz resonators (all the exhaust shops I talked to had no idea about what they were) and I have to use band clamps. The smallest resonators/glasspacks I found have a 10" case and are about 12-14" in total length. I only have about 11" between my exhaust hanger and the rear of the car so shooting a resonator straight out back may work but may be tight (no exhaust tips). I can add a bend between 45-90 degrees which will give me more room for a resonator; however, it may look wonky.

I'm running out of ideas. Has anyone had experience with drone and how to reduce it? I hear a lot about people using resonators and that's why I was thinking that route, but most of the instances I'm told about were from throwing resonators in front of the mufflers not behind. Is it a lost cause at this point? Any help would be appreciated.

I also don't care to lose more horsepower as I made 520+ crank hp and can afford to lose more.

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I don't have any welding ability so no Helmholtz resonators (all the exhaust shops I talked to had no idea about what they were)

You might search on those resonators, somewhere I saw a website how to calculate them. You could then print that out and take the info to a muffler shop?

You might want to build them in such a way that you can lengthen them/ shorten them a bit.

I don't know did the factory 340 cars have rear resonators?
 
I highly recommend a $90 flux wire Harbor Freight welder a $35 welding helmet and a $7 pair of welding gloves. In the time it would take you to cut and yell and cuss and get that damn clamp on there and get that damn clamp tight you could have ran a quick bead around it with a cheap Harbor Freight welder! LOL learn to use it on your bench on a piece of scrap metal or two. It's just like gluing stuff together but with metal. I'm not a cyber spender don't get me wrong but this would cost you less than your first visit at the muffler shop to have something hacked and cut in and put in.
 
With the Dynomax mufflers were they the super Turbo or the Ultra flows ? reason I'm asking is I run the super turbo's now on a 2 1/2 in system with balance pipe and don't get any droning where as before I had some 10in turbo mufflers don't know the brand ??? which would drone pretty bad around that RPM, around 40mph. Drove me nuts !!!:realcrazy:
 
With the Dynomax mufflers were they the super Turbo or the Ultra flows ? reason I'm asking is I run the super turbo's now on a 2 1/2 in system with balance pipe and don't get any droning where as before I had some 10in turbo mufflers don't know the brand ??? which would drone pretty bad around that RPM, around 40mph. Drove me nuts !!!:realcrazy:
Short drive...:poke: bazinga!
 
Summit has a set of glass packs with an 8” case and 12” overall length. Probably have to do something about the red paint, but they should be a better fit...

Summit Racing® Glasspack Mufflers SUM-630853

Personally, I was leaning more toward a resonator. I read somewhere that they were better than glasspacks because they use a stainless steal mesh instead of fiberglass and help more with getting rid of high frequencies. But that was just the internet. Possibly one of these:

Vibrant Performance Ultra-Quiet Resonators 1141

Vibrant Performance Bottle-Style Resonators 1792

Vibrant Performance Bottle-Style Resonators 1792

I highly recommend a $90 flux wire Harbor Freight welder a $35 welding helmet and a $7 pair of welding gloves. In the time it would take you to cut and yell and cuss and get that damn clamp on there and get that damn clamp tight you could have ran a quick bead around it with a cheap Harbor Freight welder! LOL learn to use it on your bench on a piece of scrap metal or two. It's just like gluing stuff together but with metal. I'm not a cyber spender don't get me wrong but this would cost you less than your first visit at the muffler shop to have something hacked and cut in and put in.

I actually got a cheap but good rated flux welder last Christmas, but I have been so busy with school that I didn't get past unboxing it. I have the flux core and welding gloves already, I just haven't had time to set it up and I barely got a week off work and school at the same time and that's this week. This won't happen again until after June.

With the Dynomax mufflers were they the super Turbo or the Ultra flows ? reason I'm asking is I run the super turbo's now on a 2 1/2 in system with balance pipe and don't get any droning where as before I had some 10in turbo mufflers don't know the brand ??? which would drone pretty bad around that RPM, around 40mph. Drove me nuts !!!:realcrazy:

They were Dynomax Super Turbos.
 
I'm glad to hear you got one of those welders. I think that accompanied with one of those $15 four and a half inch cutter/grinders is essential in a garage. It's going to save you thousands in the future. Just this kind of stuff. Again that present was cheaper than one trip to your muffler guy. Let alone any friend that may need a little mending or something else you want to do in the future. Again a little practice and maybe watch a couple stupid YouTube videos or something it's not difficult.
 
My Ford had muffs under the front seats off the headers and resonators (looked like long bean cans) behind the rear axle. Something about the RPM to pipe diameter and length that would cause a revision. The resonator would slow/stop the pressure wave.
 
I know I was watching some episode of Graveyard Carz where they had some resonators towards the back to tweak the sound..
Edit: Factory I believe?
 
You might want to build them in such a way that you can lengthen them/ shorten them a bit.

I don't know did the factory 340 cars have rear resonators?

Variable/adjustable length pipe. I had that idea since various sites calculated things differently and some even said it is a trial and error.

According to how they “Label” the parts on the E body cars, the typical spot where you would point and say the word. “Muffler” is called the resonator.

Just before the exhaust tips in the E body exhaust, there is what they call “The muffler.”
 
Learn to weld!

David Vizard has a write up on this and it can be a little cryptic
The way I read his drone cure is or would be a tuned pipe length after the collector/reduced (where max power has s made) would be exhaust pipe into a open sound wave canceling box with the rest of the exhaust connected to it.
 
Resonators after the mufflers adjust sound for the public before it helps you. Before the muffler helps some but it the sound waves that create the drone are large waves. The amount of sound canceling is OK but may not have the desired effect or an amount enough for you. This is a dicey thing since it is your ears, not mine that have to live with the sound.

I have tried (and suggest) the Magnaflow glass packs because they maintain the inner diameter tube size and do not neck down. They come in various lengths. There case size diameter is not to large.
 
Ditch those fancy-schmanzy chambered mufflers and install some simple glass packs. Cheap and effective... I've had them on almost every cool car I've owned for the past 50 years. No drone ever.

Try Porter Mufflers...

Around hear we call FlowMasters "Drone Masters....
 
Ford's factory "fix" on a lot of late-model Mustangs was to use two different length mufflers.

I would conclude that this also means that two different design mufflers (1 chambered, 1 not, for example), might help as well.
 
Ditch those fancy-schmanzy chambered mufflers and install some simple glass packs. Cheap and effective... I've had them on almost every cool car I've owned for the past 50 years. No drone ever.

Try Porter Mufflers...

Around hear we call FlowMasters "Drone Masters....

I don’t know what a ported muffler is. Never heard of that one.
Also, glass packed mufflers are a tasters choice. If you like it, then it is for you. I’d rather never heard that noise from f them by themselves. I’d love to never hear them ever again. IMO, that’s the sound of cheap *** coming! NOT power coming.
For sound enhancement or to help tone down, fine.



Ford's factory "fix" on a lot of late-model Mustangs was to use two different length mufflers.

I would conclude that this also means that two different design mufflers (1 chambered, 1 not, for example), might help as well.
Know for sure and do not jump to conclusions because that is “Assume” which can be bad. I am not saying your wrong though because we I do not know! ;)
I just find it hard to think the factory would use a glass pack muffler.
 
I don’t know what a ported muffler is. Never heard of that one.
Also, glass packed mufflers are a tasters choice. If you like it, then it is for you. I’d rather never heard that noise from f them by themselves. I’d love to never hear them ever again. IMO, that’s the sound of cheap *** coming! NOT power coming.
For sound enhancement or to help tone down, fine.




Know for sure and do not jump to conclusions because that is “Assume” which can be bad. I am not saying your wrong though because we I do not know! ;)
I just find it hard to think the factory would use a glass pack muffler.
No glasspacks. Just try two different length mufflers. That worked on some Mustang GTs.
 
Found this bottom view of an LX car. Seems like mufflers in the center with resonators out back.

Charger Underside 2b.jpg
 
Hemholtz is exactly what you need in this scenario. You can target that specific RPM range and lose nothing.

Powersticks aren't a bad option either. Classic Chambered Exhaust Inc. - Products

Those are all way too long. I don't have a straight piece of exhaust tubing underneath the car that is long enough for even the shortest Powerstick. I think my longest straight before the muffler is 18". Anything before and after that is bendy. Although, they said you can add resonators in the back to help with drone (See attachment - last 3 words of big paragraph).

No glasspacks. Just try two different length mufflers. That worked on some Mustang GTs.

In series or on each exhaust tube (driver vs. passenger)?

Resonator.PNG
 
“Chambered?” Has d like to see a cut away myself. Just so I understand exactly what they mean.
 
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