Drone: I might be on to something
04-30-2014, 08:59 PM
#1
1st Gear Member
Thread Starter
Join Date: Apr 2014
Location: Texas
Posts: 76
Drone: I might be on to something
Been researching drone quite a bit. Trying to figure out how to fix it. Will be trying several methods, including sound deadening material and potentially increasing the over all mass of the mufflers.
However, while doing my research, I made a discovery. I pulled up my carpeting in the rear to check out how I would be installing the material and see what was under there, and I discovered there is no spare. What does this mean? Well, this is a good start in realizing why these cars have horrible drone. The mufflers sit right under the trunk, and the spare tire well creates a nice amplifier. This certainly won't completely eliminate the drone, but I think this might be why these cars seem to get it so badly with a lot of mufflers.
So, now I am trying to figure out, what to cover/fill it with? I checked at Lowe's and couldn't find any material that I thought would work well in conforming to the trunk either.
Any other suggestions for the entire trunk and the spare tire well?
However, while doing my research, I made a discovery. I pulled up my carpeting in the rear to check out how I would be installing the material and see what was under there, and I discovered there is no spare. What does this mean? Well, this is a good start in realizing why these cars have horrible drone. The mufflers sit right under the trunk, and the spare tire well creates a nice amplifier. This certainly won't completely eliminate the drone, but I think this might be why these cars seem to get it so badly with a lot of mufflers.
So, now I am trying to figure out, what to cover/fill it with? I checked at Lowe's and couldn't find any material that I thought would work well in conforming to the trunk either.
Any other suggestions for the entire trunk and the spare tire well?
05-01-2014, 03:48 PM
#7
5th Gear Member
Join Date: Oct 2006
Location: MO
Posts: 3,234
Sound is vibration.. drone is the result of your exhaust.. and the attached car, effectively acting like a tuning fork. Padding, etc, cant get rid of it. It may change it a little... but it is still there. You can feel drone because your car is vibrating, albeit at a very low frequency.
Think of it this way.. Hold a piece of sheet metal next to a bass organ pipe. The sheet metal will vibrate as the sound (which is a vibration) hits it. At certain notes, however, it wont just vibrate at the same frequency. If the conditions are right, it will vibrate at a resonant frequency.. which may actually be more "intense" or higher amplitude than the frequency of the organ pipe.
http://en.wikipedia.org/wiki/Acoustic_resonance
This really is worth watching...really. You will know exactly what you are dealing with after this.
I think you will really relate to the sound he creates during the video... mind numbing. I had a mac axleback for a short time on my 07 v6.... I really do think it wouldn't have been safe for pregnant women.. seriously!
Adding resonators, or somehow changing the length of the exhaust system is the only way to help.. other than switching to something different... switching to something different is really the only to eliminate it.
Think of it this way.. Hold a piece of sheet metal next to a bass organ pipe. The sheet metal will vibrate as the sound (which is a vibration) hits it. At certain notes, however, it wont just vibrate at the same frequency. If the conditions are right, it will vibrate at a resonant frequency.. which may actually be more "intense" or higher amplitude than the frequency of the organ pipe.
http://en.wikipedia.org/wiki/Acoustic_resonance
This really is worth watching...really. You will know exactly what you are dealing with after this.
I think you will really relate to the sound he creates during the video... mind numbing. I had a mac axleback for a short time on my 07 v6.... I really do think it wouldn't have been safe for pregnant women.. seriously!
Adding resonators, or somehow changing the length of the exhaust system is the only way to help.. other than switching to something different... switching to something different is really the only to eliminate it.
05-01-2014, 05:04 PM
#8
1st Gear Member
Join Date: Feb 2012
Location: MN
Posts: 117
Borla touring have almost no drone, but too quiet down low for some.
05-02-2014, 06:58 AM
#9
2nd Gear Member
Join Date: May 2010
Location: Texas
Posts: 338
Sound is vibration.. drone is the result of your exhaust.. and the attached car, effectively acting like a tuning fork. Padding, etc, cant get rid of it. It may change it a little... but it is still there. You can feel drone because your car is vibrating, albeit at a very low frequency.
Think of it this way.. Hold a piece of sheet metal next to a bass organ pipe. The sheet metal will vibrate as the sound (which is a vibration) hits it. At certain notes, however, it wont just vibrate at the same frequency. If the conditions are right, it will vibrate at a resonant frequency.. which may actually be more "intense" or higher amplitude than the frequency of the organ pipe.
Acoustic resonance - Wikipedia, the free encyclopedia
This really is worth watching...really. You will know exactly what you are dealing with after this.
I think you will really relate to the sound he creates during the video... mind numbing. I had a mac axleback for a short time on my 07 v6.... I really do think it wouldn't have been safe for pregnant women.. seriously!
Adding resonators, or somehow changing the length of the exhaust system is the only way to help.. other than switching to something different... switching to something different is really the only to eliminate it.
Think of it this way.. Hold a piece of sheet metal next to a bass organ pipe. The sheet metal will vibrate as the sound (which is a vibration) hits it. At certain notes, however, it wont just vibrate at the same frequency. If the conditions are right, it will vibrate at a resonant frequency.. which may actually be more "intense" or higher amplitude than the frequency of the organ pipe.
Acoustic resonance - Wikipedia, the free encyclopedia
This really is worth watching...really. You will know exactly what you are dealing with after this.
I think you will really relate to the sound he creates during the video... mind numbing. I had a mac axleback for a short time on my 07 v6.... I really do think it wouldn't have been safe for pregnant women.. seriously!
Adding resonators, or somehow changing the length of the exhaust system is the only way to help.. other than switching to something different... switching to something different is really the only to eliminate it.
Dead on. In fact, I did a vibration research project in college on a set of mufflers to find out exactly why they drone. I have V6 with duals, so my numbers will be different than that for a GT. However, both of my mufflers had a very pronounced resonance mode sitting around 2250 Hz. For a V6 traveling approximately 75 mph, the engine frequency output of the exhaust is damn near close to 2250 Hz.
Mufflers are all made differently, thus producing a very different sound profile. Unfortunately, he's right, the only way to eliminate the drone is to switch mufflers. More unfortunate is you will have no idea what the resonance profile the muffler is before you buy it. Unless you test them first... Without switching mufflers, your only choice is to mask the sound by sound dampeners in the trunk and cabin, keeping the RPMs as low as you can, or turning up the radio... Sorry!
05-02-2014, 07:59 AM
#10
3rd Gear Member
Join Date: Sep 2011
Location: DE
Posts: 546
I can tell you that my car has a spare, and with the flowmaster outlaws it droned like crazy! I also have the stock resonators and I imagine it would only be worse without them. I switched to off-road x, and a lot of the drone went away. The car is super loud, but it doesn't have the head rattling drone like before with cats.