Exhaust drone help!!!

[dabears2322]

Does anyone know which catback or axleback systems come with Helmholtz resonators already designed into them to eliminate drone? This is such a common problem I'd think there would be many of them, but I can't find any. Do people just not mind 100db+ of in-cabin sound while simply cruising around??

Many systems do not have drone. Borla, corsa and ARH for sure do not have any drone to them and sound great.

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[Socalmustang]

^^^I think sound sometimes sound is is over-exaggerated....I have the Corsa Xtreme, which is considered one of, if not the loudest exhaust on the market. The exhaust is not crazy lound in-cabin, unless you drive at very high RPM's 4k+ or under constant WOT....Great thing about it is when you are just cruising...You can barely hear it, but downshift and throttle it....It is loud. To me, it's the perfect exhaust. No drone whatsoever.

Radio on, windows up, cruising at steady speeds, you really wouldn't even know the exhaust is there.

Best thing to do is find someone with an aftermarket exhaust and see it for yourself.

 

[AlphalphaMale]

I'm going to disagree a bit - absent a Helmholtz resonator ALL aftermarket exhausts that are loud will drone. It's simply unavoidable because it's a function of the exhaust producing loud-volume sound at the frequencies the interior of the cabin resonates to. Unless a manufacturer has somehow built baffles that remove that frequency of sound (usually in 100-150Hz range) entirely from the output you'll get drone. The best analogy to this is that the interior compartment in the car is like a tuning fork - hit it with sound at its natural resonant frequency and you get additional noise from the interior joining in on that frequency.

 

[AlphalphaMale]

If anyone is interested I wrote up a sample solution for determining the length of the HH resonator section needed to cancel out drone at a given frequency (in the example I assumed 120Hz as the offending frequency).

You can determine what frequency is the worst with your exhaust by downloading an app on your phone (I use RecForge Lite on Android) and use it to record the sound in the car. Then take that file to your computer and use a tool like Audacity (open source and free audio editor). Open the sound sample in there and you can use it to determine what frequency was the loudest in the section where you know you heard the most drone. Here is a step-by-step HowTo on how to get that frequency analysis done:

https://pantherfile.uwm.edu/type/www/420_Field_Audio/FrequencyAnalysis/FrequencyAnalysisAudacity.htm

Here's what an exhaust that has Helmholtz resonators designed in looks like (this is the HKS Hi-Power for 370Zs) - the resonators are the smaller cans that are dead ends and come off 90 degrees right before the final mufflers:

 

[Chameleon]

Drone master ^ :clap2:

 

[rio16]

Drone master ^ :clap2:

+ 1 :clap2::clap2:

 

[Cars_1959]

There are lots of exhausts that do not drone. I wouldn't put bandaids on the magnaflows. Just get a different exhaust.

The only ones I've heard that don't drone are Corsa and Ford Racing by Borla>

I'd like to know any besides these two that don't drone.:hail:

Thanks

 

[MtnBiker]

Cruising at highway speeds (60 - 75ish) I can only hear a faint, and quite livable, rumble with my Borla S-type catbacks. Seems like the system is tuned to be quiet from about 1800 to 2400 rpm or so.

 

[Chameleon]

The only ones I've heard that don't drone are Corsa and Ford Racing by Borla>

I'd like to know any besides these two that don't drone.:hail:

Thanks

I just installed the MBRP street catback. I've watched the CJPP video of it 100 times and can say after installing it myself it has zero drone. Great system.

 

[nastang87xx]

I'm going to disagree a bit - absent a Helmholtz resonator ALL aftermarket exhausts that are loud will drone. It's simply unavoidable because it's a function of the exhaust producing loud-volume sound at the frequencies the interior of the cabin resonates to. Unless a manufacturer has somehow built baffles that remove that frequency of sound (usually in 100-150Hz range) entirely from the output you'll get drone. The best analogy to this is that the interior compartment in the car is like a tuning fork - hit it with sound at its natural resonant frequency and you get additional noise from the interior joining in on that frequency.

That's way too much of a generalized statement. I have long tubes, high flows, no resonators, and the Borla ATAK axle back on my car. It is laughably stupid loud. No drone because that's just how the mufflers were designed.

 

[madweazl]

Cruising at highway speeds (60 - 75ish) I can only hear a faint, and quite livable, rumble with my Borla S-type catbacks. Seems like the system is tuned to be quiet from about 1800 to 2400 rpm or so.

Rumble at 60-75? Anything over 65 is just flat out loud (PP like you it looks like), like radio at minimum 1/3 output to even it out. Damn near half volume to drown it out. Under 1900rpm it is quiet but anything above that and it gets loud. The S Type is literally right at the edge of obnoxious for me; anything more and I'd take it off and go another route. Everyones threshold for acceptable levels of noise are different but damn, these things are loud (especially in cabin). While drone has never bugged me (my '88 GT truly was obnoxious with headers, offroad H pipe, and the American Thunder cat back LOL) I just couldnt deal with any more noise as I actually like to hear my music and be able to talk with my passenger at the same time.

 

[MtnBiker]

Rumble at 60-75? Anything over 65 is just flat out loud (PP like you it looks like), like radio at minimum 1/3 output to even it out. Damn near half volume to drown it out. Under 1900rpm it is quiet but anything above that and it gets loud. The S Type is literally right at the edge of obnoxious for me; anything more and I'd take it off and go another route. Everyones threshold for acceptable levels of noise are different but damn, these things are loud (especially in cabin). While drone has never bugged me (my '88 GT truly was obnoxious with headers, offroad H pipe, and the American Thunder cat back LOL) I just couldnt deal with any more noise as I actually like to hear my music and be able to talk with my passenger at the same time.

I agree that the S-Type is probably at the upper limit of ... to me pleasantly hooligan. This is not a road trip car for me. It's my decompression device after a hard day of work. There are times when I'm in a gear low just to hear it better. I've had several friends do ride-alongs and nobody seems anything but impressed with how the Borlas sounded when playing and when cruising highway speed. Perhaps loud music in my mispent youth has caused enough hearing loss to make these more tolerable? Dunno. But I find them pretty civilized on the highway. Truly a YMMV situation. Isn't it great how many options we have from this amazing aftermarket!

 

[Jeffy_2010]

Alright so finally got around to having my shop install the j-pipes. The drone is totally gone at 60-67mph but now I swear it drones from 70-75... Is it just me being crazy or did it make my exhaust louder or what?

 

[nastang87xx]

The J bends could have introduced a new frequency issue but is it actually droning or are you just looking for it so hard you're misinterpreting it?

 

[Jeffy_2010]

No it's actually droning, it also vibrates my seat now in which it used to not.

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