Daytona Drone

[DoubleD]

I know this topic has been beaten to death on here, but I can not find an answer to my question. I have a 1992 Daytona IROC R/T. It has a 3" exhaust, down pipe back and soon to have a 3" down pipe too. I have a "Dynomax" Race Bullet Muffler in the middle of the car and a Magnaflow Oval muffler in the rear. There is no CAT. I added the rear muffler a year ago to quiet it down but the car still drones bad at highway speeds. I am understanding that this could be due to my exhaust exiting on the driver side slant cut at the same height as the bumper. So I am willing to extend it past the bumper, I am just looking to see what other people have done for a tail pipe and if this gets rid of the drone. Here is a pic of the back of my car. Thanks in advance.

Thinking this down pipe may be part of the problem too.
http://i84.photobucket.com/albums/k6/brmsnowboarder/IROC%20RT/76759153_photobucket_56613_.jpg

http://i84.photobucket.com/albums/k6/brmsnowboarder/IROC RT/DSCF4194.jpg

Here is a pic of the back of my car. Thanks in advance.

[4 l-bodies]

Exhaust noise is very subjective. With that said, IMO if you are going to keep the 3" exhaust, you are going to need to put on a chambered muffler. The hole is just too large to really be quiet. Every 3" straight thru muffler I have heard on a TM will get maybe not droney, but loud anyways at certain RPM's. I had two 3" straight thru mufflers, a oval GN ATR billet muffler and 3" round stainless Ultraflow on a masi 16V omni trying to quiet the car down. It was acceptable in the end, but just barely. WOT was still louder than I wanted.
I have no cat and one chambered muffler on my 3" exhaust on my Shadow. Yes I'm losing some HP with it, but it's not loud or droney at all. For me, lesson learned.
Todd

[wallace]

Have you tried the weights they put on luxury cars exhaust? If you look under the Lincolns you'll see them attached to the exhaust pipe. that's what they are for to eliminate noise/resonance. It's cheap and doesn't restrict flow may be worth a shot to see if it helps. I've gotten a couple out of the junkyard to try and kill the horrendous drone I have on my wagon but have not had time to try them out.

[RoadWarrior222]

Definitely get it exiting clear of the bumper and bodywork. If you want to test, find an old rad hose the same diameter and cut an elbow and/or a 6" straight off it, and you can aim it down, off to the side, etc etc, to see which works best...

[turbovanman²]

If its at the stock location, that's pretty good. As for drone, I've chased it for years. Make sure the exhaust doesn't touch any part of the car, use OE rubber hangers, and put a cat in place of the front muffler otherwise run some form of an OE type muffler or chambered muffler IE import Flowmaster as they have more drone control. You'll lose a bit of power but if you want quiet. I finally shut mine almost up and now have a 3.5" cutout if I want full power. Should have done that years ago, :banghead:

[DoubleD]

Does anyone have pictures of a Daytona with 3" exhaust? I want to see how the back will look.

[DoubleD]

I have been looking at pictures of Daytona's on Pbase and Google Images and I have yet to find one Daytona with 3" exhaust exiting below the bumper. All of these cars seem to be exiting behind the bumper, I don't get how they don't drone. Any help would be greatly appreciated with pictures too.
Thanks

[phantomrt]

Isn't the drone a resonance? A certain RPM generates a certain frequency that resonates and that is where the darn noise comes from. There is such a device which can read the frequency of such sounds, and I think one of the objects is to not get the exhaust quieter, but to generate sound waves that are out of phase of each other so that they cancel each other. How to do that, I do not know, but if we can determine the wavelength and create exhaust exits that do this, it may accomplish the goal somehow.

or maybe I am just thinking of it all the wrong way.

[Reaper1]

Drone is resonance, yes. However, if the tip exits behind the bumper, it traps the sound and amplifies it at certain frequencies making it worse. The 2nd and 3rd gen G-bodies with ground effects are kind of difficult to get the exhaust tip past the bumper without cutting the cover. I don't suggest that simply because it ruins the cover. However, adding a turn-down that aims the exhaust down and away from the car will help not only the sound inside the car, but outside as well.

Another thing to try, some sort of dynamat over top of where the rear muffler is. The whole rear hatch of G-bodies is VERY good at amplifying low frequencies (part of the reason they are good for bass on big stereos...about 22Hz IIRC). It doesn't restrict flow, it only adds a little weight, and it could possibly solve the issue to the point of being acceptable.

As Simon stated, take off the middle muffler and put a hi-flo catalytic converter in its place. The ONLY reason I have a cat on my car is to reduce the decibel level and the drone. It did exactly what I wanted it to! Hey, and I can claim I'm making a good bit of power WITH a cat in place...that blows some people's minds. My exhaust tip does extend past my bumper cover by maybe about 1/4" or so, but my bumper cover is a stock Shelby Z one, so it doesn't have any sort of rear ground effect on it at all.

[DoubleD]

Here is how my current exhaust exits the back.
http://img.tapatalk.com/d/13/03/23/a8e2u9a3.jpg

[DoubleD]

Two more up close pics.
http://img.tapatalk.com/d/13/03/23/2edy2y5e.jpg
http://img.tapatalk.com/d/13/03/23/4aqude9a.jpg
Any input is appreciated.

[Rrider]

I would get one of those band style muffler clamps and a 45 bend. Extend it out and see what it does. Try pointing other directions if straight back doesn't do well.

If you don't like chambers, try a louvered core muffler. Its a good compromise between a straight thru and a chamber.

[Reaper1]

I agree...extend the tip out farther. And as stated above, try different angles, too.

Have you installed a cat in place of the center muffler, yet?

[contraption22]

I would also try extending the tip, and possibly adding some Dynamat type product. There are other quality alternatives without the Dynamat name. Just try to stick with butyl products vs asphalt.

I've also heard of people trying laying heavy moving blankets over the floor of their trucks or cargo areas with varying degrees of success.

[phantomrt]

Ultimately, I think the G-bodies are acoustical nightmares. I drove a dynamat-filled IROC R/T a few hundred miles to Ohio years ago, and it was still loud. Base model G-bodies of this era have no sound insulation in the trunk, and the ES models and better do, but it doesn't seem to make much difference either way.

Feel free to give experience otherwise, but at ~2800 RPM on the highway, the 4 cylinders are at their loudest. The V-6 cars are at their quietest at 2800 RPM and are at their loudest at about 2100 RPM. I see sort of a pattern here, but would need to do some calculations to determine the frequency and wavelength of the exhaust of a 4 cylinder engine at its 2800 RPM and that of a V-6 at 2100 RPM. Create dual-exhaust tips that are spaced apart so that the sound waves are 180 degrees apart from each other, and they should, theoretically, cancel themselves. Also, the length of both exhaust tubes would have to be a "multiple" of each other to make this happen.

Or maybe I am over-analyzing the situation or maybe the wavelengths will prove to be impractical to work with--if the wavelength proves to be 7-feet or so.

[phantomrt]

Interesting. I just did some quick calculations, and I'd like others' opinions on what I discovered.

Assuming that the number of power strokes that an engine makes per engine revolution directly corresponds to exhaust frequency...

a 4 cylinder engine performs two power strokes per engine revolution. Simply put, you take the RPM and multiply it by 2 in order to get the number of power strokes per engine revolution. 3,000 RPM * 2 = 6,000 power strokes per minute. This is right about where I find the 4 cylinder engines to be the loudest.

A 6 cylinder engine performs three power strokes per engine revolution. Simply put, you take the RPM and multiply it by 3 to get the number of power strokes per engine revolution. 2,000 RPM * 3 = 6,000 power strokes per minute. Right about where the 6 cylinder cars are at their loudest on the highway.

Coincidence? I'm not sure yet. I am going to punch up some more numbers to see what else I can find. I am unsure as to how the doppler effect is going to come into play here. In theory, that would require factoring in the velocity of the exhaust and speed of the vehicle. Vehicle speed minus rear-ward exhaust velocity. I have no idea what the exhaust velocity is. Bigger exhaust should result in slower exhaust though. hmmm

[phantomrt]

Okay, I didn't plan on coming to any conclusion that is actually starting to make sense, but it is starting to seem a bit less coincidental.

6,000 power strokes per minute is 100 power strokes per second. That is 100 hz. Thinking that was low, I pulled up a youtube clip of a 100hz sine wave to compare. Darn, that sounded strikingly similar, though I haven't driven my loud 4 cyl G-body extensively for over a year now.

So, at sea level, at 72 degrees fahrenheit, the speed of sound is 763 mph. Subtract 60 mph since that is the speed the car is moving at a V-6's loudest, and you get about 700 mph Doppler-corrected sound speed. The wavelength of 100 hertz sound wave moving 700 mph? 10.3 feet! That is pretty darn close to the dimensions of the combined steel passenger and luggage compartment of a G-body. Conditions are sufficient for exhaust tone resonance.

As a side note, when driving my Geo Metro which lost its muffler several months ago, I could move my head closer to the windshield, and the exhaust drone became substantially more bearable.

So, I thought more about my idea of dual exhaust tips to cancel the noise and have not yet factored in the wavelength in hot exhaust so I am going to assume the same 10.3 foot long sound wave. With a sound wave 10.3 feet long, it would only take a 5.15' space between the tips to produce sound waves that are 180 degrees out of phase from each other, which is do-able. However, the length of the exhaust tubes would have to be considered. Unless you can find a way to make the exhaust tubes exiting the left and right side of the car equal length, the sound waves will not cancel each other. The sound will have to travel an extra 5.15' to the other side of the car by just splicing in a "Y" behind the rear "axle", so the sound waves are going to match up when they are emitted, and thus accomplish nothing.

Any brainiacs out there who can de-bunk this?

These conclusions are strengthening my ideas of a faux-dual exhaust setup with an electric cut-out, so I can divert the exhaust to a muffler on the passenger side when I want to, and then have balls-out exhaust out the drivers side, or possibly a little bit of both.

Lastly, has anyone considered an audio noise cancelling setup? Basically, all that would be necessary is some kind of amplifier, speakers, and microphone in the rear of the car that inverts the sine wave and emits new sound to cancel it. Fighting sound with sound in other words.

[Reaper1]

Seems to make perfect sense to me! :thumb: Good job!

Now, keeping in mind I haven't driven my V6 Daytona since the early 2000's, I seem to remember my V6 Daytona being its loudest at right around 60mph, which I think was around the 2000 rpm area.

Now, something I learned and fully agree with is from a site somebody posted up here (possibly in this thread) about different sound reducing materials.

Dynamat (and similar products) are made to reduce panel rattling and resonance. To reduce actual SOUND decibel level, you need some sort of closed cell soft foam to absorb and insulate the inside of the car. Let me see if I can find that link and I'll repost it.

---------- Post added at 01:08 PM ---------- Previous post was at 01:03 PM ----------

Here's the link to the site that I learned the information from and it all makes perfect sense.

http://www.sounddeadenershowdown.com/

HTH :thumb:

[phantomrt]

The principle that article is working on is the fact that sound is emitted from a source, which vibrates whatever is in its way, and then vibrates the air on the opposite side which reaches a person's ears. If something is in the way of the vibrations (such as a steel panel) and it resists the vibration, the noise is inhibited and won't pass through it very well.

With this in mind, a vibrating panel needs the sound deadening stuff to be firmly attached. With the factory original sound mat in the trunk, it isn't going to help stop those low frequency/long wavelength vibrations much. The sound is going to hit the steel, and the steel is going to vibrate around and "slip by" the sound insulation. Now, if that sound mat is firmly attached, the steel cannot vibrate without the mat vibrating as well. Since the mat doesn't like to vibrate, the sound is stopped much quicker. The sound mat can probably be loose if the wavelength is short enough.

Hmmmmm. In theory, that dynamat stuff would be quite efficient by just strategically placing squares of it every here and there, but it should still be effective when covering something in its entirety. Oh well... its getting a bit late to think.

If I ever get blessed with boredom, I think it would be cool to test my theory of the equal length exhaust pipes and placing their tips 5.1 feet apart from each other. The math works out to a point, but since sound undoubtedly travels a different speed through steel and the sound will undoubtedly hit the steel before the waves meet each other to cancel themselves, the distance the exhaust tips will need to be placed will have to change because the wavelength has changed.

[contraption22]

Interesting point to add to your theory.

Srt4 owners with unequal length dual outlet exhausts have reported more drone with unequal length dual exhausts than with equal length pipes, or single exhausts.

[DoubleD]

Wow, this discussion got very complicated and technical, I wish I could chime in more. I need to dig back out my NVH textbook from college.:clap:

[phantomrt]

I'd like to read that book. Definitely post something if you find out. But to be honest, sound waves alone are not a complicated thing to understand. But one thing I don't quite understand is how it correlates with its transmittance through a substance other than air. Sound travels much faster through materials such as steel, and the wavelengths become much longer as a result. If I am thinking right (which has been frequently known to not happen) resonance occurs when a sound wave bounces back and hits another incoming sound wave, in which their amplitudes add to each other and causes the drone a.k.a a "standing wave". For this to happen, the entire sine wave has to complete itself in the distance that it has to work with before it bounces back so it has a chance to resonate. If just the crest of the wave hits a wall and bounces back, the trough of the wave which has not yet bounced off the wall will cancel the reflected crest. However, the crest will be reflected at a lower amplitude, so the trough will over power it and the sound will not be perfectly cancelled, but the amplitude will be reduced. To put it simple, 100 hz sound isn't going to resonate in the chassis of a car because the wavelength is way too long. Significantly higher frequencies such as wind noise and road noises can. Adding sound deadening stuff that sticks to the chassis won't do anything because the chassis cannot resonate with such a low frequency. The exhaust sound is going through the metal chassis and coming in contact with the air inside the vehicle, which just happens to have a wavelength of about 10 feet, which is the size of the passenger compartment. Simply having a notchback setup car would put more barriers in the way of the sound and lower its volume in addition to having a passenger compartment that is less than the wavelength, so the wave isn't going to resonate... at least not at 100 hz.

Ever notice when the next door neighbor has a party, all you can hear through the walls is the bass? That's because the long, low frequency wavelengths aren't hitting anything that can cause them to bounce back efficiently or get fully absorbed. The higher frequency stuff with the shorter wavelengths are more easily trapped in a wall and such.

Certain military communication systems utilize gigantic antennas so they can create super long wavelengths which are really tough to jam, because you need a transmitter with an antenna just as big to receive the radio wave and re-create and invert it in order to cancel those radio waves and thus "jam" them. At least I think that is how it works.

I need to talk to an engineer about it. I know some people who are working for Bose here in the twin cities. I may try them.

[Reaper1]

The resonance comes from the application of sound waves or vibration at a certain frequency to a given volume (of air). It's the exact same concept as a subwoofer box. Even though we can prevent the chassis from reaching its natural frequency (for the most part), the sound waves still make it into the volume and resonate inside the volume.

So, decreasing the amplitude of the waves is the only real option as we can't alter the frequency (sort of...I'll get to that in a minute). To do that you need sound absorbent material...something that reduces the amplitude. Dynamat does NOT do this very effectively. It's job, and what it was designed for, is to eliminate the panels from vibrating and making it sound like the car is falling apart.

Ever notice those black bags that Chrysler stuffed in certain voids in the cars behind the interior panels? Those are sound absorbtion devices. Notice how they don't weigh 2 tons, aren't physically attached to the metal, and are squishy? That's because they are an open cell type of material meant to reduce the amplitude of the sound coming from that area. A closed cell material would work even better.

An active sound suppression system would be pretty neat, and probably not hard to implement, but the thing is, you HAVE to have dedicated speakers in the car for that, or risk loosing sound quality from your music stereo. This type of system on that scale would add weight and complexity to the car, but if you are willing to deal with that, then I'm sure something pretty simple could be made to do exactly that. Just sample the sound in the car with a microphone, run it through a sound wave analyzer, have a logic system that delays the output of the sampled sound by 1/2 of the wavelength, then pump the output to an amp and some speakers. Done. Now,what other kind of problems might this create....who knows? It might interfere with your music! That would suck! :(

[DoubleD]

Back to the topic at hand, I was under my car last night running an amp wire to my trunk. I noticed that when I had my friend install my rear muffler, he had issues getting it mounted, it looks like the exhaust can swing and hit the frame of the car in a couple of spots, there is also no mount at the very rear to support it. I have a feeling all of this movement may be causing the drone, I need to take my car in and have the mounts fixed, I will get this done while I have my V- band welded on for the Jackson-made Holset Down Pipe. It was a mess under there...

[Reaper1]

If there is no mount holding the muffler, then usually what happens is the pipe going over the axle will hit something in that area and rattle. Plus, yes, the exhaust is very much free to swing around. The rear mount for the muffler is pretty darn important! :thumb:

[DoubleD]

I have the mount that would look to be inline with the rear tires "sorta" (too much side to side movement for me) mounted, but the mount at the very rear is not attached to anything. Going to take the car to a shop and have it done right! Only issue is finding someone to work on my car with no muffler.

[Reaper1]

Just tell them Neon SRT-4's didn't come with mufflers from the factory and your car is the same! :thumb:

[DoubleD]

I didst mean muffler, I have two of them. I mean Catalytic Converter. I don't have one of them.

[Reaper1]

Ohhhh! Yeah, unless they do work under the table, most shops now won't mess with that stuff.

If you get a good high flow converter, it WILL help the drone. I can't remember if that was covered in this thread on not, but I figured I'd mention it. Good converters aren't a restriction to high power anymore. Are they more than straight pipe? Yes. So much you'll notice it? Not unless you are looking for that last n'th of power.

[Rrider]

I band clamped a 90 bend at my exhaust tip pointed towards the driver's side. It seems pretty quiet at 45 degrees to the ground. Its less droney than my other car with the pipe exiting straight back. I'll experiment with swiveling it to some different angles to the ground later.

[DoubleD]

I am in the process of swapping turbos and when I went to remove my down pipe, one of the 3 bolts was missing and the other two were not very tight, my down pipe was not very securely attached to my turbo. This could be part of the problem. Getting ready to install the HE 341 and Jackson's down-pipe,then take the car to a shop to have the rest of my exhaust re-attached. The v-band connection should make sure this never happens again.

I also have gone thru and covered the entire rear floor with A mass loaded material and I am replacing all of the non-existent carpet padding. I covered and padded the spare tire well also. I hope all of this helps, I also added a nice Kicker 10" Sub in a ported box in the spare tire hole. I would like to get the drone managable or make it go away mostly. Time will tell thou.

[DoubleD]

This should really help with the drone up front at least, much cleaner, and much more free flowing.

http://i84.photobucket.com/albums/k6/brmsnowboarder/IROC%20RT/IMG_20130516_181248_354_zpsb10a3354.jpg (http://s84.photobucket.com/user/brmsnowboarder/media/IROC%20RT/IMG_20130516_181248_354_zpsb10a3354.jpg.html)​

[jayspartanburg]

nice.. when you get a chance could you snap a quick pic of the sub box

[88C/S]

Very good thread. Just make sure none of your exhaust system is touching the body or cross member. if you have no space between downpipe and the firewall, you will definitely have a drone when driving. If you have an after market bobble strut, don't have it pre-loaded, just have the nuts to where they prevent the engine from rocking back under acceleration.

[Reaper1]

If you have an after market bobble strut, don't have it pre-loaded, just have the nuts to where they prevent the engine from rocking back under acceleration.

I agree with this 100% if you have filled, or poly mounts. However, with stock mounts, a little preload (not much!!) will go a long way in helping wheel hop and even smoothing out the shifting.

[DoubleD]

I have a combination of filled and poly mounts. I think I put a lot of preload on the strut before, I will put very minimal on it this time.

[DoubleD]

Took my car to a local shop to a guy that has been in the business for 40 years. He did great work, ended up swapping the Dynomax turbo muffler for a Magnaflow resonator. He welded that into my system and attached that resonator to my new down pipe. He also added an extra exhaust clamp to the rear and really limited the movement, the drone is much less now.

http://i84.photobucket.com/albums/k6/brmsnowboarder/IROC%20RT/IMG_20130523_165900_902_zps8bf0559a.jpg (http://s84.photobucket.com/user/brmsnowboarder/media/IROC%20RT/IMG_20130523_165900_902_zps8bf0559a.jpg.html)
http://i84.photobucket.com/albums/k6/brmsnowboarder/IROC%20RT/IMG_20130523_165907_510_zps9ec9c553.jpg (http://s84.photobucket.com/user/brmsnowboarder/media/IROC%20RT/IMG_20130523_165907_510_zps9ec9c553.jpg.html)

[Reaper1]

You didn't happen to get any pictures of the inside of the resonator did you?

[DoubleD]

I did not but the Google images search function works very well, the part is a Magnaflow resonator PN# 14419.

http://i84.photobucket.com/albums/k6/brmsnowboarder/exh_zps238d1c84.jpg (http://s84.photobucket.com/user/brmsnowboarder/media/exh_zps238d1c84.jpg.html)

[Reaper1]

Cool, so they aren't louvered. That's what I wanted to know! Thanks! :thumb:

[DoubleD]

Drone is still there, but I think that is because my V-band clamp does not fit perfectly. When I run my hand around the connection I can feel a big leak right there. Will wait for more comments till my Mopar clamp comes that is made specifically for this. I hope this fixes it because my buddy was over with his Holset powered Spirit and his is quiet in the car but loud outside, opposite of mine..

[phantomrt]

Unless it is a massive half-inch wide or bigger gap at that leak, it isn't going to affect the drone noise much, if at all. It can quiet it down a bit, but such exhaust leaks like that do not contribute to such noises.

[DoubleD]

Ok, so I drove the car through the summer. It is fine and dandy to drive with the windows down, but the drone can be a bit much when driving with the windows up. Will installing a high flow cat bring the drone down and not negatively affect my performance too much? I want a nice high flow 3" straight cat. I want to stay Magnaflow, which one should I get? The car will be making around 425 whp, so I don't want to restrict my exhaust too much but I see a nice high flow cat in my future do reduce drone and the un-burned junk coming out of the back of my car. Any suggestions or personal experiences?

[Rrider]

On my 90 I had 3" from the turbine housing to the rear bumper with nothing. No cat and no muffler. I then added a magnaflow 3" cat in and it did quiet it down. I have a brand new magnaflow muffler sitting on the shelf that I didn't bother putting in. I'm still using this same setup with only the pipe bends and the cat as my mufflers. I can't comment on power.. its not even half what you're talking about.

[Reaper1]

The way I chose my high-flow cat was to choose the largest GVW with the diameter of pipe I wanted to use.

[DoubleD]

Did some experimentation on my car tonight. Went to the local custom exhaust shop and had a 3" 45 degree angle pipe made. I attached it to my current exhaust with a band clamp and got it all sealed up. I took the car for a drive and the drone is nearly all gone. The car has a mean resonance at 2900-3100 rpm. I hear this is common, but thru the rest of the power band the car is substantially quieter. Now to come up with a clean exhaust tip look.

http://i84.photobucket.com/albums/k6/brmsnowboarder/IROC%20RT/IMG_20131014_182838_527_zps471c8fed.jpg (http://s84.photobucket.com/user/brmsnowboarder/media/IROC%20RT/IMG_20131014_182838_527_zps471c8fed.jpg.html)

- - - Updated - - -


nice.. when you get a chance could you snap a quick pic of the sub box
Here you go. It is a simple 10" Loaded Kicker Enclosure with a 250 watt Scoche Amp. Sounds Great. Need to make an Amp mounting plate and a spare tire cover out of some 1/2" MDF.

http://i84.photobucket.com/albums/k6/brmsnowboarder/IROC%20RT/IMG_20131014_222026_871_zps354c38ec.jpg (http://s84.photobucket.com/user/brmsnowboarder/media/IROC%20RT/IMG_20131014_222026_871_zps354c38ec.jpg.html)

[DoubleD]

The exhaust may look ugly, but it is functional. I have put about 300 miles on it now. Extending the exhaust past the rear bumper has solved just about everything. I have some wicked vibrations between 2800-3100 rpm, but the car is quiet in the rest of the range. Next year I will have the tail pipe redone, debating on one large 3" exit or dual tips? Glad to know I don't have to put a converter on the car and it is basically open with a resonator and muffler, very free flowing.

[x.Gen]

went thru all the different stages on my G-body with exhausts. factor in a 3" SV and .63 turbine from the start, it was LOUD when I started - too loud.

from noisy with drone, to acceptable, my experience was - stock DP with adapter & 3" pipes (only) back, full 3", then with a race bullet in the middle, then with a 6" round magnaflow, then added the 59959 metallic high flow converter, and lastly a tip. mixing cat-back pipes with the stock DP, drone was unbearable - with or without the race bullet. I couldn't drive comfortably because the locals look for any excuse to light you up around here. and to be honest, I could smell the fuel without the cat, which any smart cop can. getting rid of the stock DP was essential in losing some resonance...and thinking back, the cat made probably the biggest difference in quieting the drone. I have the cat and the muffler mid-mounted consecutively, and could rear mount a second muffler if I wanted (but don't). most vibrations I got were on the OTA pipe at the brace for the track bar - pretty tight in there, everything needs to be just right not to hit some of the time.

I really have to say the cat made little to no measurable difference in exhaust flow, I did not feel any difference in performance. it passed emissions like nothing, and sounds sweet. I think the other factor to killing the drone was the 6" round - could have tried 8", but looked tight at the heat shields and didn't want to chance rubbing anywhere. the race bullet probably made it louder, it certainly wasn't any help. looking back I wish I'd have done the cat sooner, I had low expectations from everything I read previously. was impressed with that particular cat.

[jonnymopar]

Anybody try the Moroso spiral flow mufflers or something similar on a G body? I've got 2.5" turbo-back with no cat and a cheap 28" long glasspack down the middle. I've never been particularly thrilled with the sound, but I swear it's gotten louder recently. I'm also getting older, so it might just be that too.

[Reaper1]

I had a friend that had one of those "Spiral Flow" mufflers on his Shelby Z. It wasn't too bad, but it didn't make that much difference in the sound versus a Magnaflow.

I personally like the Borla XR-1. I fell in love with it a long time ago. It has a different sound than the other straight through mufflers I've heard and tried. To me is sounds more "rumbley" and it doesn't get that top end "buzz", plus the body and the packing are stainless. They are a little pricey, but to me it was worth it. My system is a full 3".

I DO suggest putting a high-flow cat on it if are wanting to drive it long distances or a lot. They make a huge difference in the volume of the exhaust and they also help get rid of drone (as long as the tip extends past the bumper or side). Plus, the new units are not that restrictive (if at all depending on your set-up), so performance loss will be minimal and you can make the tree nazis happy-ish.

[x.Gen]

Anybody try the Moroso spiral flow mufflers or something similar on a G body? I've got 2.5" turbo-back with no cat and a cheap 28" long glasspack down the middle. I've never been particularly thrilled with the sound, but I swear it's gotten louder recently. I'm also getting older, so it might just be that too.

from what I read before I did my exhaust, way back: 2.5" actually drones worse than 3". and glasspacks wear out, at least mine did. I don't think it's uncommon. then that thing was more like an amplifier than a muffler when I replaced it.

[Reaper1]

Yes, any fiberglass filled muffler will eventually "wear out". There are mufflers out there (mostly motorcycles) that you can buy new packing for them because it "wears out".

[jonnymopar]

from what I read before I did my exhaust, way back: 2.5" actually drones worse than 3". and glasspacks wear out, at least mine did. I don't think it's uncommon. then that thing was more like an amplifier than a muffler when I replaced it.

Wow, where did you read that the 2.5" drones more than the 3"? I've never heard that, but with all the weird acoustical anomalies with these cars, I wouldn't be surprised. I've got an exhaust shop near me that I trust, plus I've got a 3" O2 housing, so maybe I should just go 3". Regardless, the glasspack has to go. It's got about 40k miles on it, and for the price I paid for it, I bet it's junk by now.

[x.Gen]

ran across it during years of pointless surfing...remember it being more prevalent when 2.5" was commonly available and 3" less commonly, like (gulp...how old am I?) back on the old SDML, and I'm sure it came up a few times on TD, early on. also from partial experience, personally having started the 3" with the cat-back and stock DP. running that on the road, you can't miss it in-car - highway drone close to unbearable before (stock DP to 3" back). the tone definitely changed with the 3" DP, kind of mellowed/broadened it (hard to describe). more than noticeable improvement going to the 3" DP, can't imagine the highway drone on a full 2.5".

[Rrider]

My minis back that up. I wouldn't say the 3" DP car is necessarily quieter, but for sure its less droney.

[DoubleD]

Here is what else I did last year to combat the drone, I cleaned the floor really good and then laid down peel and seal on the floor and the rear wall, then picked up some new sound deadener to replace the old, worn out stuff. Really seems to help!

http://i84.photobucket.com/albums/k6/brmsnowboarder/IROC%20RT/IMG_20140422_173058_765_zpse0426b9d.jpg (http://s84.photobucket.com/user/brmsnowboarder/media/IROC%20RT/IMG_20140422_173058_765_zpse0426b9d.jpg.html)

http://i84.photobucket.com/albums/k6/brmsnowboarder/IROC%20RT/IMG_20140422_173047_093_zpsb0a4e101.jpg (http://s84.photobucket.com/user/brmsnowboarder/media/IROC%20RT/IMG_20140422_173047_093_zpsb0a4e101.jpg.html)

[Reaper1]

How much weight did that stuff add?

[DoubleD]

I have 2 rolls in there at 4 lbs each, I have a 10 inch sub and amplifier back there, I am not worried about every pound, I will take a minor increase in weight for better sound from the stereo and the car.

[Reaper1]

8 pounds isn't too bad. Especially if it makes a significant difference.

[Vader85]

The way you stop drone is to use the biggest mufflers possible......your choice were wrong from day 1....

[DoubleD]

Drone is all but gone now!

http://img.tapatalk.com/d/14/05/29/de6ena9y.jpg

[Reaper1]

THERE ya go! :clap: It doesn't look as sexy as one may like, but it gets the job done. Even extending my tip no more than 1" from the bumper made a HUGE difference in my car.

[DoubleD]

Been driving the car for a couple of months now. Exhaust is holding up well, took it on a few longer drives and the drone is almost completely gone, its is a little louder over 2700RPM, but so much better everywhere. If you have drone, extend your tip past the bumper. Another notable thing, with the exhaust coming out the back, when you get on it it sounds a lot better, the exhaust sound leaves the car. I get many more comments about it now. At a recent auto-cross event, I had a few people come up to me and compliment my car on its sound. It's a real low, throaty with the added boost sound. Need to get a outside of car video of it soon!

[turbovanman²]

Pretty cool fix. I have a GTC in with a Hushpower muffler, I'll report back on noise but she was pretty good when I drive her in. I've read good reviews on flow.


The way you stop drone is to use the biggest mufflers possible......your choice were wrong from day 1....

Been there, got the badge, all they did was quieten down the exhaust but the drone remained.

[DoubleD]

Tossed my buddy the keys and told him to make a pull while I videoed, car sounds good IMO, it is a lot quieter exhaust wise than I believed it to be, you can really hear the turbo!

https://www.youtube.com/watch?v=-Xq2VizCOsk&index=1&list=UUWDkZSLTgazK0D_qp_8GcKw

[DoubleD]

Update on this, been driving the car all summer and it still has a nasty drone spot at 3000 rpm under load, as you approach 3k it gets progressively louder and once past 3k quieter, there is a definite resonance right there. Not sure how to fix this, everywhere else the car is quiet, was thinking of removing my 45 degree tail pipe that makes the flow out the rear parallel with the ground, try a straight section and see if bouncing the exhaust waves off the ground helps. I've seen many Daytona's with slanted tail pipes. Jackson's cars come to mind.

[Reaper1]

When I had my turbo mini the exhaust was super short...downpipe, muffler, turn-down....right at the back of the front seats basically. It was super loud with no turn-down on it, but with the turn-down it was much quieter. It wasn't "quiet", but there was a significant difference.

As for the resonance it is a product of the inside volume of the car. It acts like a bandpass speaker box, so the exhaust tone note hits the natural frequency of the interior of the car and the sound waves amplify each other. The best way to reduce this is to push the sound waves and vibrations from the exhaust away from the car and isolate the exhaust as much as possible. A turn-down can (most probably will) help.

[DoubleD]

Originally my exhaust was had a turn down, but it was before the rear bumper, so all of the sounds was directed back behind the bumper and into the cabin. Having a simlar turn down that exits beyond the bumper should help I hope. I am going to try an experiment and see if it helps, I should have a short section of straight 3" pip laying around to test with. My exhaust is fully isolated from the chassis and is held inplace well, it does not have much movement.

[turbovanman²]

The Hushpower muffler worked awesome, drove it home a few times and no drone, which is awesome for an auto car. 2.5" exhaust, no cat.

[DoubleD]

I have a magnaflow resonator in the same spot a cat would go and a magnaflow oval muffler out back. Sound is really good, minus the one spot of drone, interior is plenty quiet enough for me.

[DoubleD]

I did some testing last night, I tried having my tail pipe coming off at an angle, extending it, then trying a longer 45 bend to get the exhaust coming straight off, nothing seemed to work better than my current set up. Drone was still there and bad at 3000 rpm.

So this morning I did some more research. I am looking into adding a side branch resonator into my exhaust. These are proven to work really well at removing drone. Just need to do some frequency testing, some calculations, then decide where to install it. I think there is some drone at 1500, comes back again at 3000 but far worse and is also noticeable at 4500, but at that point I'm making power and don't care. There's a pattern here..

[RoadWarrior222]

Yup, harmonics...

http://www.themeandvariations.org/Images/other/harmonic_series.png

See also.. http://hyperphysics.phy-astr.gsu.edu/hbase/waves/funhar.html

[jrbexhaust]

DoubleD - I wish I would've read this earlier. I can solve your drone issue with one muffler. PM me!!!

[jrbexhaust]

Plus I'm local to you!!!

[Reaper1]

Well don't keep it a secret. What is this muffler that has the power to get rid of exhaust drone?

[jrbexhaust]

Heartthrob HVS muffler. Trust me. Now, they are oval body mufflers. This means you have to be crafty to install it. I would get the offset in/center out due to the frame rail and spare tire well. I can get you a good deal too. PM me if interested.

[turbovanman²]

Hmmmmm, might be something to try on the van, but tired of spending money on exhaust, lol.

[DoubleD]

I have already invested in a muffler and and resonator and the pair work very well quieting "most" of the noise while still giving me a completely open exhaust when I want it. I just want to cancel out the nasty drone at 3000, everywhere else the car is good, I had a buddy riding with me last night and he was shocked how quiet it is the car at 2500 rpm around 55. The tone is great and I dont want to change it, I just want the nasty 3000 rpm drone to be eliminated. My buddy is doing some calcs and is going to give me the proper length for my side branch resonator. I will then have my local exhaust shop bend it up and install it. I'll give it a try and see how it goes.

Here the current exhaust tone:

http://i84.photobucket.com/albums/k6/brmsnowboarder/th_IMG_0567_zpstxna4zb3.mp4 (http://i84.photobucket.com/albums/k6/brmsnowboarder/IMG_0567_zpstxna4zb3.mp4)

[jrbexhaust]

Think of this. If you remove the muffler, resonator, and not put the next resonator on you will save a decent amount of weight savings. Add in that those three create turbulence. One muffler is a plus.

- - - Updated - - -

Tell you what, I will buy the muffler. You try it. If you like it, buy it. If not, give it back.

[jonnymopar]

ell you what, I will buy the muffler. You try it. If you like it, buy it. If not, give it back.

God dammit, I could have used a deal like that at the beginning of the summer!! Oh well, there's always next year.

[DoubleD]

I took jrbexhaust up on his offer and installed the heartthrob hvs muffler in place of my magnaflow muffler. I have it temporarily installed now. Drone seems to be non existent at 3000 rpm now. Now the car is quieter with the windows up rather than down. I made sure to extend the muffler tip parallel to the ground and beyond the bumper, both things seem to make a huge difference in drone. More testing to continue, but first impressions are positive.

http://images.tapatalk-cdn.com/15/07/08/26ba2be7b6b2bb835730964feddcdb96.jpg

[Reaper1]

I would be interested in some back pressure testing as well as on track (because that's what really matters).

[Ondonti]

I would be interested in some back pressure testing as well as on track (because that's what really matters).
http://www.4btswaps.com/forum/showthread.php?1615-muffler&p=64902&viewfull=1#post64902



I spoke to Mike at Heartthrob this morning. Part #101 is an IMCO stock type muffler. He said it is very quiet. The HVS is their "free flow" muffler and the HPM is their performance turbo muffler. The HPM is the quieter of the two. I copied the info below from their 40 page online catalog.

Exhaust Flow Tests for 3” exhaust
CFM Backpressure
Heartthrob HVS #54144 248.5 0.25
Flowmaster #943042 233 0.50
Heartthrob HPM turbo # 1142 o/c 222 0.25
Heartthrob HPM turbo # 1142 c/o 218 0.25
IMCO #914 turbo 182 0.666
IMCO muffler #101 (stock type) 140 0.50

Link to their catalog: http://www.heartthrobexhaustinc.com/2004cat.pdf

[DoubleD]

For reference the HVS I'm testing is #54044, only difference with the above one is mine is center/ center and not offset/center.
The magnaflow is #12219.

[DoubleD]

Permanently installed the muffler now, took the car out of town last weekend. No drone at highway speeds, there is slight drone and it does get louder on decel, but the car is 100 times better now. Very happy with this muffler. Been getting positive comments on the exhaust tone, I love the tone idling and cruising.

[tryingbe]

Bump, Double D, how's the Heartthrob 54044 holding up?

I'm looking for a quiet muffler as well. Thanks.

[jonnymopar]

Any pics of the install? I'm liking what I've read about these mufflers, but I'm hoping I have enough room with a 3" pipe on a Daytona that's lowered 1".

Also, how's the spool sound? Any louder or softer versus the Magnaflow?

[tryingbe]

I installed the Heartthrob 54044 on my GLH.

Tone sounds about the same, volume maybe down 5-10% than the Dynomax straight thru muffler I had. I was expecting it to be a lot quieter, not just a bit quieter.

I wouldn't recommend it.

[jonnymopar]

I installed the Heartthrob 54044 on my GLH.

Tone sounds about the same, volume maybe down 5-10% than the Dynomax straight thru muffler I had. I was expecting it to be a lot quieter, not just a bit quieter.

I wouldn't recommend it.

Heh, this gets posted 3 days after I ordered mine. Honestly, I'm hoping anything will be better than my 2.5" exhaust with the deteriorated 8-year-51k-mile-old $30 glasspack up the middle.

[DoubleD]

I was never expecting the muffler to really quiet the car down, I wanted to kill the obnoxious drone. Under full load and full boost, I think the car may be louder than before, but at that point I only hear the turbo anyways. What I was trying to do was kill the bad drone between 2600-3200, and the nasty peak at 3000 and this muffler did it for me. I would not say this muffler will quiet the car down, but that was not my goal, only drone control.

[jonnymopar]

I was never expecting the muffler to really quiet the car down, I wanted to kill the obnoxious drone. Under full load and full boost, I think the car may be louder than before, but at that point I only hear the turbo anyways. What I was trying to do was kill the bad drone between 2600-3200, and the nasty peak at 3000 and this muffler did it for me. I would not say this muffler will quiet the car down, but that was not my goal, only drone control.

That's good to hear, since your objective was the same a mine is. My car is on the highway quite a bit when it's nice out, and with the 555, I'm right in the middle of the "drone zone" at highway cruise. I've found myself at times going a bit faster to get past that resonance - probably a bad thing.

[DoubleD]

Yeah, I didn't want to loose any performance, but the drone was killing me. I need that 3" complete exhaust to flow as much as I can with my end goals.

[contraption22]

Originally Posted by Dude on another site back in 2009
I spoke to Mike at Heartthrob this morning. Part #101 is an IMCO stock type muffler. He said it is very quiet. The HVS is their "free flow" muffler and the HPM is their performance turbo muffler. The HPM is the quieter of the two. I copied the info below from their 40 page online catalog.

Exhaust Flow Tests for 3” exhaust
CFM Backpressure
Heartthrob HVS #54144 248.5 0.25
Flowmaster #943042 233 0.50
Heartthrob HPM turbo # 1142 o/c 222 0.25
Heartthrob HPM turbo # 1142 c/o 218 0.25
IMCO #914 turbo 182 0.666
IMCO muffler #101 (stock type) 140 0.50


Link to their catalog: http://www.heartthrobexhaustinc.com/2004cat.pdf


The problem with this comparison is that it only compares it to other baffled mufflers, which really aren't that great for a turbo car.

[DoubleD]

Resurrecting this old thread as I am trying to make my car quieter when I want it to be. The Heartthrob HVS muffler has been working great, I have taken this car on many road trips and it is a joy to cruise on the highway. Planning to replace the front Magnaflow resonator, with the Vibrant Ultra Quiet Resonator and adding a Magnaflow High Flow Cat right in front of this resonator. This will get rid of the gas smell and should quiet down the exhaust. I want it a little quieter on start up so I don't wake anyone when I come to and from home. To balance this out, I'm planning to add a 3" Loudvalve right after the downpipe and before the cat so I can get a nice straight free flowing exhaust when it start making boost and power.

[Reaper1]

I am curious, there's decibel meters you can download for your phone. Give that a shot and see what kind of difference things make inside and outside of the car. Remember decibels are logarithmic, so even a few actually is a BIG difference.

[DoubleD]

I am planning to pull the motor very soon for some maintenance and upgrades. I will try and get some readings that I can share with the group so I can quantify before and after numbers with my planned exhaust changes. I have measured the decibel level before but I do not recall the numbers I got.

[player1up]

fyi, phantomrt was on the right track. No need to add mufflers or anything that inhibits flow.
Google "Helmholtz resonator exhaust" , "side branch resonator tube" , or "1/4 wave resonator tube"

The drone on my car was so bad that you literally couldn't talk at 2200rpm. Based on the frequency, my tube ended up being 44" long so I had to get VERY creative with placement.

One thing that I'll say is that I hadn't really expected it to work as well as it did but it made a huge difference.

[chromguy]

fyi, phantomrt was on the right track. No need to add mufflers or anything that inhibits flow.
One thing that I'll say is that I hadn't really expected it to work as well as it did but it made a huge difference.

Do you have pictures of the finished install?

[player1up]

Miles, Sorry, Have been away a bit, I'll PM you for an email address. You have to promise not to laugh at the install, it's 44 inches of pipe tucked up inside the diffuser on my Consulier. ;)

I did a bit of research before I went ahead with this test, but since I had all of the pipe and stuff laying around I decided that at worst I'd be out an afternoon worth of time and at least I'd KNOW. Besides, I HAD to do something about the drone. It also seemed to tone down almost the entire RPM range, made things a little less "buzzy" overall.

Keep in mind this is for a VERY short exhaust and it still works.

[DoubleD]

Over the SDAC weekend I had a Vibrant Ultra Quiet resonator and Magnaflow high flow catalytic converter installed to replace my 3" Magnaflow resonator. The drone is a lot less at highway cruising speeds between 55-65mph. I was able to have a conversation at a normal talking level. I will have to take some decibel measurements. I also added a Loud valve boost operated cutout right after the down pipe that opens at 8psi. I will say when the valve opens, the car gets really loud.
https://uploads.tapatalk-cdn.com/20190702/db6560fd1c217486eed1bf93db47addc.jpg
https://uploads.tapatalk-cdn.com/20190702/eb1ee9abe133c84e1ffd6af00047f7d1.jpg