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Alright, let me say first that I am still a newbie...I've been reading and reading and reading about exhausts. Had my SE for about 3 months now and am about to put on duals with x pipe and Flowmaster Super 44s and no resonators this weekend. I know I'll have drone but don't know how bad it will be. Thus in antipation of this, I've been reading lots of on the subject. Most people will say put some resonators on or use dynomat, etc. but I came up with and idea and wanted to what you more experienced gear heads think or if anyone has tried this.

My understanding of drone is that at certain RPMs the exhaust system resonates at the same frequency. The idea of resonators is to change that frequency to a different RPM range to get rid of it. Taking the analogy of rubbing your finger around a wine glass and then putting your hand on the glass to stop the resonance, I was thinking of getting some stainless steel clamps the same size as my pipe. Then get a tube of high temperature, silicone caulk (something non water soluble) and lining the inside of the clamp and place it on the exhaust pipes. I figure this would have to change the harmonics of the exhaust piping. I just have no idea in what direction (i.e. good or bad). I also don't know what this would do to the exterior sound. Let me know what you all think. Thanks.
 

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I think there's been alot of engineering and R&D done by alot of different companies to reduce/eliminate drone, and if it was as simple as you describe, it would have been done already.

Even if, in theory, it could work, I think you would spend a month of sunday's trying to figure out the right spot to put these clamps, as well as the size of the clamp etc...

Mike
 

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My understanding is that drone causes not only surface vibration of the pipe but transmission of sound through the pipe wall as well. To stop transmission, the OEMs would occasionally use double layer tube because that would dampen both transmission and vibration.

Your idea about installing vibration dameners would address the vibration problem. You would still have the transmission, and, as you indicated, the enhanced sound from the exit as well.

The resonators are a good idea because they don't present the wave with a defined exit point where it can reflect. Instead the resonator shows the wave an array of seeming "exit" points so reflections aren't all in phase.
 

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I concur with Ottopilot. Your method seems plausible to at least improve the isolation of the exhaust. If there's a resonant frequency though, it may also have to do with direct transmission from the exhaust exit into the trunk and/or cabin and resonating there.

I'd say just hang off until you hear how bad it is. I don't think you'll mind unless it hits hard @ a cruising speed you frequent. Pretty rare that it's on the money in the sweet spot. Then you can start your mad acoustic experimenting - which I fully expect extensive notes/posts on. ;)
 

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I'd actually really like to hear what you come up with if you do in fact try this out. I'm sure it's not as simple as some clamps, (as many manufacturer's spend a lot of time addressing the drone issue) but your idea might be enough to change or re-direct the sound and atleast make a difference. I'd love to hear/see anything you find out here!

-Alec
 

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Sounds like something worth some experimentation. It will probably end up like one of those things that kinda works halfway, but not quite good enough to defeat drone altogether. The pipes will get some well needed damping, but there will still be considerable acoustic output from the exhaust exit anyway.

As for places to try, go for the midpoint on a pipe between 2 suspended or braced points or bends. Then look at the qtr points in between those. Lacking a computer simulation, you can be fairly certain that the strongest antinodes will show up at the mid lengths of a suspended physical section. That also implies that the suspended points on the ends could similarly benefit from a damping treatment. Then continue to new 1/2 and 1/3 points between the treated points.
 

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Alright, let me say first that I am still a newbie...I've been reading and reading and reading about exhausts. Had my SE for about 3 months now and am about to put on duals with x pipe and Flowmaster Super 44s and no resonators this weekend. I know I'll have drone but don't know how bad it will be. Thus in antipation of this, I've been reading lots of on the subject. Most people will say put some resonators on or use dynomat, etc. but I came up with and idea and wanted to what you more experienced gear heads think or if anyone has tried this.

My understanding of drone is that at certain RPMs the exhaust system resonates at the same frequency. The idea of resonators is to change that frequency to a different RPM range to get rid of it. Taking the analogy of rubbing your finger around a wine glass and then putting your hand on the glass to stop the resonance, I was thinking of getting some stainless steel clamps the same size as my pipe. Then get a tube of high temperature, silicone caulk (something non water soluble) and lining the inside of the clamp and place it on the exhaust pipes. I figure this would have to change the harmonics of the exhaust piping. I just have no idea in what direction (i.e. good or bad). I also don't know what this would do to the exterior sound. Let me know what you all think. Thanks.
Hey Radelman70,
This a great question. The drone an exhaust system is subjective and is not limited to Flowmaster mufflers alone. The drone everyone refers to is the actual note that comes out of the exhaust pipe and is produced from pulses that come from the valves opening and closing and the firing order of the cylinders. Some drivers are more in-tune with it than others. When we design a bolt-in system for a vehicle, we try to find the perfect balance of tone and performance. There’s a lot of R&D that goes into each system.

Regarding toning down the drone, since drone doesn’t come from the actual steel being pounded by exhaust pulses, it would be impossible to change by isolating the pipes from the clamps. The only way to really eliminate drone, if you have it, would be to change the firing order and valve timing or add additional mufflers and/or resonators.

If you have further questions about the differences, call us toll free at: 1-800-544-4761</SPAN>
 

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No Drone Baby!

I have a 2010 RT automatic. I have the Flowmaster Force II (with resonators). I love this system. "NO DRONE BABY!" Not too loud while not too quiet. Just enough "GRUNT." The tone of the exhaust changes when MDS kicks in but it is barely noticable. This convertor back system is probably the lowest cost out there too. I also like the fact that the original tips are used. This keeps the price down while fooling evryone else that your system is stock... that is until you start it up.

StevoHemi
(Mods.... "Classified information.")
 

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Discussion Starter #9
Well, I wanted to report back here regarding my results.

On Friday night I picked up some red high temperature silicone and used two clamps about 1/4 bigger than my pipe. I placed the clamps about a foot from the tips and let it dry overnight. On Saturday my family and I took a trip about 3 hours each way. Based on what I recall from driving it everyday it didn't have much effect--if any. Still had some drone in the lower rpm ranges, but certainly none over 50mph. This car is really quiet and my wife commented on it while we were cruising at 70-75mph. So overall, this little experiment failed. But it was good to try. Just going to figure out now if I want to do anything about the drone. As I've driven a week with it, I'm getting more used to it.
 

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Well live and learn I guess, it's cool that you did try it out though! you wouldn't know if you didn't try. Sorry about not having much of an effect, but thanks for keeping us in the loop with it. Good luck with any future ideas, keep us updated!

Alec
 

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As said before, the drone itself is coming from the engine and just being transmitted through the exhaust. But, much like playing a musical instrument, you can change the harmonics by bending and squeezing a tube here and there to get a different sound. Having said that, sometimes you can place several stainless steel clamps tightly around the pipe in certain strategic locations to break up the harmonics resonating down the pipes. A bolt screwed into the pipe can also change the harmonics. Denting the pipe with a hammer can also have an effect (although not recommended). Twists and turns, weird angles, bulges and indentations, can all break up the harmonics enough to push it to another level and hopefully beyond that of the cruising RPM range. It's all trial and error, and what works for you might not work for someone else.
 

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I think the two best bets for getting the pipe vibrations minimized would be to wrap the pipes with header wrap, and to undercoat the bottom of the floorpans with a rubberized undercoationg so that the sheetmetal doesn't resonate either. DO both of these and I bet there would be a significant reduction.

Wednesday I am going to undercoat my RT (mvoing from GA to OH where they salt the roads) and I will report if there is any drone or rear end whine reduction (my car has a little of both).
 

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Ditto on the thanks for reporting back.

Interesting. If you decide to continue your experiments, & you run across a ton of lightweight material (whole bunch of cardboard, foam, etc.), fill your trunk up; then try filling the rear passenger area. I have a suspicion there's a standing wave bouncing around back there somewhere. (rusty ex pro-audio guy)
 

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I ran straight pipes for a week on my r/t 6 speed.
You dont know what drone IS until you run straight, it was a NON STOP migraine, drone at nearly every normal driving rpm/gear.
I put the bottle mufflers on the rear where the reso's were originally and left the reso's out and it barely has any drone now (maybe even less than stock, but I can't be sure as I had the week of drone hell in between, so my memory may be skewed)
 
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