Drone noise - can people expand...

[cbutler32]

I have a question about interior "drone" noise...
It has been posted on the Zoomers thread (38+ pages of it) that the magnaflow system has a drone to it...
and that is why so many went that route with the zoomers system as it doens't "have" it...
can someone expand on this?
better yet...
does anyone have a magnaflow system that is going to be at the Garden Grove meet next week?
As I know there will be several that have the zoomers system...
Thanks in advance!!!

[btlfed1500]

Originally Posted by cbutler32

I have a question about interior "drone" noise...
It has been posted on the Zoomers thread (38+ pages of it) that the magnaflow system has a drone to it...
and that is why so many went that route with the zoomers system as it doens't "have" it...
can someone expand on this?
better yet...
does anyone have a magnaflow system that is going to be at the Garden Grove meet next week?
As I know there will be several that have the zoomers system...
Thanks in advance!!!

Drone is a subjective qualitative characteristic of all exhaust systems. Freuqency and amplitude will vary as design changes. Each persons own "interpretation" of acceptable levels and their own personal auditory capacity wil determine what is appealing to them.

Often times people ASSUME things from previous experience and have not really heard for themselves the actually product in question. Some people assumet that based upon other experiences with products they can make generalizations for all products. Unfortunately that is not goign to lead to valid assumptions.

Example:

F-Body (Camaro / Firebird) Our kit is loud and has some degree of noise both insdie and outside the cabin. This product was designed around a perfromance enthusiast customer ... by definition and market study these people were seeking power as premier and were willing to sacrifice other componets such as drivabilty and comfort. Our cat-back caters to that criteria.

The LX chassis on the other hand is entirely different and our strategy is altered to provide a larger degree of comfort whiel still providing a power enhancing part. These are trade offs but not those made by simple coinsidence.

Our cat-backs are NOT culminations of universal parts and pipes. Pipe diameter, resonator or muffler style, shape, volume and perforation core VARY by application. YES thats right ... putting our universal parts off the shelf together to the same configuration as our cat-back will NOT net the same results. This is why we sell BOTH universal and Cat-back configurations.

Our cat-backs are engineered ... not fitted and replicated. We have a 30,000 sq ft facilty housing two test engineers running two in-ground Mustang and Dynojet dynos, Superflow and Horuba flow benches, 1/3 octave 32 band spectrum analyzers and 4 other engineers designing internals and supporting our Computer Aided Drafting design department. My fabrication and design staff pride themselves in putting out product DESIGNED for its applciation.

It would be interesting to hear some impressions regarding noise / drone / resonance from actual owners ... I know they are out there .... we are still selling over 50 systems a month.

Some threads from owners:
Some miles with the SRT-8 and Magnaflow
Cat-Back Exhaust..Borla or Magnaflow...
Cat-Back Exhaust..Borla or Magnaflow...
Looking forward to blowing away alot with my Magnaflow!

Searching shows more ... seems to be plenty of info.


Richard

[3SRT4ME]

My experience, and I believe that of many others, is that the objectionable drone was a function of the interior tone/resonance change brought about, and emphasized by aftermarket catbacks, by the C going into MDS or 4 cylinder mode. Given that are SRT8s are always firing on 8, I don't envision the drone issue being nearly as prevalent, if at all present.

[ChuckG]

Richard- Maybe you could explain and define exactly what "drone" actually is.

TIA

[vvv90]

Originally Posted by cbutler32

I have a question about interior "drone" noise...
It has been posted on the Zoomers thread (38+ pages of it) that the magnaflow system has a drone to it...
and that is why so many went that route with the zoomers system as it doens't "have" it...
can someone expand on this?
better yet...
does anyone have a magnaflow system that is going to be at the Garden Grove meet next week?
As I know there will be several that have the zoomers system...
Thanks in advance!!!

What do you mean by drone Chris? When do you get it, at what RPM, etc...?

[btlfed1500]

Originally Posted by 3SRT4ME

My experience, and I believe that of many others, is that the objectionable drone was a function of the interior tone/resonance change brought about by the C going into MDS or 4 cylinder mode. Given that are SRT8s are always firing on 8, I don't envision the drone issue being nearly as prevalent, if at all present.

A dramatic harmonic is introduced when the motor shifts MDS modes. We had to incorporatea completely different design to counter this shift. We started with an external x much like the factory part but when the exhaust pressure was reduced the dampning effect of the x was as well reduced. We had to locate the x all the way inside the first muffler (mid-body) and perforate the x to minimize the MDS "buzz."

Now as far as resonance goes, this noise is function of the noise cancelling capacity of the muffler AND system pipe design. Both noise and harmonics due to exhaust pulse contribute to cab resonance (this is the loud booming in the cab) that typically occurs when the engine is under high load and low throttel position. There are many ways to combat this ranging from harmonic dampners to changing exhaust pulse character through modifying turbulance/laminar flow, speed/heat and balance such as that provided by a cross over tube of sorts.

Each application changes how effective a certain approach will be at reducing noise. There is NO one best way. I does infact take time and testing.

Richard

[rmedina]

I had the zoomers on for about a day. I had to take that thing out.. The tone was never constant. What I mean is that the sound of the exhuast was never the same. When you are cruzin it sounds ok but once you ease off the gas then give it some it sounds horrible inside the cabin. For example if you are out on the streets and come to a red light. Once you give just a bit of gas it would make this ugly knocking noise. The guys around here all told me it because there is no backpressure and the hemi does require some bp. The weird thing is that you can only here the knocking noise from the inside of the car. From the outside it sounds nice. Go figure..

Rmedina

[Kewl 'Nilla Hemi]

Originally Posted by rmedina

I had the zoomers on for about a day. I had to take that thing out.. The tone was never constant. What I mean is that the sound of the exhuast was never the same. When you are cruzin it sounds ok but once you ease off the gas then give it some it sounds horrible inside the cabin. For example if you are out on the streets and come to a red light. Once you give just a bit of gas it would make this ugly knocking noise. The guys around here all told me it because there is no backpressure and the hemi does require some bp. The weird thing is that you can only here the knocking noise from the inside of the car. From the outside it sounds nice. Go figure..

Rmedina

I've had Zoomers for a couple of months and I've never heard a horrible "ugly knocking noise" from the inside (or outside). Is there any other way to describe this noise? You said yours made this noise both when you gave it a bit of gas as as well when you eased off the gas?


Audrey
Hers: '05 'nilla C....fully loaded except engine block heater, volant cai, zoomers, tint, painted engine shroud w/ss trim kit

His: New arrival: '05 1500 Dodge Ram P/U Quad Cab w/hemi (of coarse)

[rmedina]

Originally Posted by Kewl 'Nilla Hemi

I've had Zoomers for a couple of months and I've never heard a horrible "ugly knocking noise" from the inside (or outside). Is there any other way to describe this noise? You said yours made this noise both when you gave it a bit of gas as as well when you eased off the gas?


Audrey
Hers: '05 'nilla C....fully loaded except engine block heater, volant cai, zoomers, tint, painted engine shroud w/ss trim kit

His: New arrival: '05 1500 Dodge Ram P/U Quad Cab w/hemi (of coarse)

Not when I ease off the gas, just when I gave it just a little. For example when you are out looking for a parking space at a grocery store. Stop and go driving.. The noise was similar to a dump trunk. As soon I as gave it more gas it would go away..

[aperformance]

Originally Posted by rmedina

I had the zoomers on for about a day. I had to take that thing out.. The tone was never constant. What I mean is that the sound of the exhuast was never the same. When you are cruzin it sounds ok but once you ease off the gas then give it some it sounds horrible inside the cabin. For example if you are out on the streets and come to a red light. Once you give just a bit of gas it would make this ugly knocking noise. The guys around here all told me it because there is no backpressure and the hemi does require some bp. The weird thing is that you can only here the knocking noise from the inside of the car. From the outside it sounds nice. Go figure..

Rmedina

One day? I've never heard any one complain about any type of drone or resonance at any speed. Was it knocking like "pinging" cylinder detonation? Did you check for any leaks? Was the system clamped and welded? Sorry to hear of your problem, before you took them off perhaps we could have discussed a possible solution. I guess everyone’s ear is different and tolerant to different sounds. Our patented tip design does a good job canceling out the exhaust pluses that cause drone or cabin resonance. We developed the venturi tip for just this purpose to cancel out the noise with out loss of performance.