Cale Sahl

iTrader: (2)

Case in point, I have an SLP LoudMouth I system on my car. For my taste a little loud and raspy so I might change it up a little after I get the headers on this weekend.

Has anybody run a resonator in the intermediate pipe as well as a traditional muffler out back? I'm wondering how the resonator would impact the sound, maybe make it a little deeper/bassy?

jaybdaboat

I'm Curious too.

midias

I did on my old Monte Carlo with a v8 and on my solar a with a v6. Both were perforated straight through. I have had with and without and I really like with better. I plan on integrating one in my TAs exhaust soon

antman89iroc

I used 2 ultra flow bullets in my head pipes a ultra flow in the stock location and a mini bullet in the tall pipe. All straight through. Sound is deep. The bullets and mini did help. After i finished i discovered the mini bullet (resonator no packing) would have been better placed in the mid as you are suggesting. Since it has no packing it imparts a whooshing sound to the exhaust. Not bad but i noticed it. I would put the largest ID muffler in your location that well fit. The dynomax ultra flows are good pieces in my opinion although the smaller versions aren't stainless. Regardless your idea will work but straight through mufflers or resonator only knock a few decibels out. That's why i used 4 to get the sound level i wanted with the high flow i needed.

STREETDEMON

i believe the loudmouth system just uses a resonator...no muffler.

dynomax uses the race bullets for resonators in there systems that need them. and since they are a zero loss muffler, you won't hurt your flow while taming the rasp.

midias

There is a 90% chance I will be adding this to my Y pipe to go with my magnaflow exhaust.

www.summitracing.com/parts/wlk-24250/

STREETDEMON

i would go with one that is a little longer, like 12".

midias

I might, It all depends on what measurements I come up with when I get the car in the air.

midias

Just installed a Dynomax 24222 race bullet. Unfortunately it is still snowing here no I could only here it parked in the garage. But it sounds really good with my magnaflow muffler

http://www.dynomax.com/race-series-b...und-24251.html

Muffler Body Height 4"
Muffler Body Length 12"
Muffler Body Width 4"
Muffler Inlet Diameter 3"
Muffler Overall Length 16.5"

lha1992

So i see everyone is using the dynomax stuff as a resonator an it's construction is basically like a glass pack of some sort. Could I just go buy a glass pack an do the same as how everyone in this thread is doing? I would be cutting the cat an welding it in place of the cat.

lha1992

I also have stock exhaust on my car too. It's a 91 firebird with a 305 an 5sp.

antman89iroc

Yes a "glass pack" type muffler and resonator are basically the same thing. As far as I can see the term "resonator" is generally used when it is in addition to the main muffler and for a specific purpose of dampening a resonance in the exhaust. Even stock cars have them. Also, it seems a resonator is shorter and has less packing or sometimes no packing. Sort of a crappy muffler. In my case I installed the "resonator" which was actually a "race bullet" muffler with no packing at the rear of the tail pipe. I believe it would have served it's purpose better if I had placed it just in front of the axle to dampen the resonance in the large diameter, long piece of tubing going down the middle of the car. Regardless, I installed 4 straight through mufflers since I chose to stick with single exhaust and wanted high flow and modest sound level. I couldn't find a turbo or chambered muffler that would flow enough to handle my 414ci motor without running duals.

midias

Glasspacks also generally are louvered and not perforated.

Perforated core resonators do not affect flow at all. Louvered core resonators will flow about 5-15% less but do a better job at silencing things.

midias

Also if so you only use a glass pack then it will be quiter if you have a longer pipe after it

antman89iroc

Perf core resonators/mufflers do flow better than louvered ones. This is generally accepted and has been proven in tests. However perforated core mufflers do present the exhaust stream with some resistance to flow. If located near the engine it/they affect the "tuning" of that length of pipe. Now I'm not a fluid dynamics engineer but the way I understand it the restriction comes in the form of sound wave disturbances. When the exhaust "pulse" enters the series of holes it bounces through the media, hits the exterior wall and bounces back through the holes. This happens at each hole and with diminishing intensity from the entrance to the exit. I think of it as a blurring of the stream sort of like when you see heat of a black top road in the summer disturbing light waves. The energy (sound) the muffler absorbs isn't free, it doesn't just disappear, rather it is muted somewhat by the mufflers ability to bounce the sound waves through the media. The exhaust passes through a section which vibrates the stream and causes it to lose some of it's energy and turns it into heat. There is also the aerodynamic affect of each of the holes "side wall" causing air to hit them and bounce off which disturbs the laminar flow of the exhaust. It's not the same as say using a flow bench to test the mufflers CFM at a given pressure drop. The pulsations of the cylinders firing change the dynamics of the exhaust stream. Still, the back pressure created is far less than a louvered core or chambered muffler of the same ID.

midias

You are correct that my my bad for pulling directly from a website. Although at most of our power levels we are not maxing out the flow of a 3" perforated resonator or a 3" pipe. Although yes there is a difference.

As for sound dynomax claims about 4db down with their race bullets.

antman89iroc

4bd lol, going from 122bd to 118bd is still loud. It's difficult for the ear to detect that amount of change. However, every little bit helps and sometimes it isn't the sound level but the tone or frequency that is objectionable. 3" will handle most street vehicles with a good muffler and 3 1/2" cover the rest up to fire breathing monsters or turbo/nitrous hogs. Every combo is unique and each person has different tastes, play around with different combinations and see what you like. I started with a 3 1/2" in the stock location and ended up adding 2) 2 1/2 in each head pipe and a race bullet/res. at the tail pipe. I like my combo and the neighbor rarely say I wake the baby. It doesn't drone going down the highway, I'm happy. But it took trying different things til I got what I wanted.

midias

4db is about 1.7x in power ratio. It is noticeable, maybe not at volumes so high where the ear hits a flat response. But 4db is a noticeable difference. At least that is my experience working as an engineer on audio systems.

Resonators are generally going after a change in tone more than sound level. Getting some rasp and drone out of the system.

antman89iroc

Agreed, again I'm not an engineer but a -4bd rating on a muffler isn't going to make a car exhaust sound much different at the sound levels we're talking about here. +4db in sub woofer response may be noticeable. +4db at 4k probably very noticeable.

midias

It will remove or dampen harmonics which will lower the overall SPL. What dynomax really needs to quantify is if the 4db is an average or just at one point in the spectrum. Ideally I should have taken a spectrum plot before and after but I am really just hoping to remove some rasp and some drone. I can tell you with my two bros exhaust on my bike the silencer removes about 5db 96-91 and it is very noticeable

This is a fairly good read.

http://www.enoisecontrol.com/wp-cont...rrier_wall.pdf

antman89iroc

Yes, I'm sincerely not trying to debate whether 4db is noticeable or not. As you have pointed out there are many things going on and what may be objectionable for one individual, or in one situation, may not be a problem in another. If someone feels their car is too loud, -4db is probably not going to satisfy them. You've hit on a point though in that many times it's not the spl but a frequency issue. Your statement about dampening harmonics is a key factor. Using a sub woofer as an analogy the right size box with the right diameter and length port is what amplifies the sound at a certain frequency, it gets the right resonation within the port to make the sound (0r feeling) we want, louder. Conversely, an engine is emitting a whole spectrum of sound energy and often times it just so happens that the diameter and length of exhaust tubing happens to resonate one (or possibly more) of those frequencies and that's were the resonator comes in. Properly placed it can "disturb" that perfectly tuned sub woofer port in the exhaust pipe to make the tone of the exhaust more pleasant. At that frequency the race muffler rated at -4db may actually reduce the spl far greater than -4db. There is so much going on in the exhaust system that I don't fully understand but what I have found is having a plan and reason for each component selected and then some trial and error seem to work for me. The other factor which is important to power is restriction which is easily measured with a fitting in the pipe and a low pressure gauge. In the end an exhaust system that first provides ample flow for the performance requirement and also sounds pleasant is achievable by many different methods.

midias

I have driven around with the resonator in place for a while. The difference was far more noticeable than expected. Cruising is the most noticeable area far less annoying on expressways. The whole system is a quieter but sounds much better as a whole. I dont think I will be reversing it.

89gta383

iTrader: (5)

antman89iroc,

do you have any pics of your exhaust? I have a 4inch mufflex system with a 4in dynomax ultra-flo and want to quiet my system down by either putting in another 4inch ultra-flo in the pipe before the rear-end turnover pipe.

I am trying to keep flow also, but reduce some sound.

antman89iroc

Yeah I hear ya! Sorry but no pics yet. I may be able to get some up. Since I don't have a cat I ran both head pipes basically straight back by the trans and put 2 2 1/2" Ultra flow muffs beside the trans before the Y pipe. My main muffler is in the stock location with a single exit on the drivers side. I think your idea of putting an additional muffler or resonator right in front of the axle is a good plan. I think it will help most in that location because of the resonance of the large mid pipe. I put a resonator at the end of the tail pipe but it did little to help. I feel it would have had more affect in the location you proposed.

Another interesting note. I recently replace my carpet. I went to extra measures to add dampening mat (like dynomat) to the floor pan but also added a lot of carpet padding (juke-like poly padding) I lined the wheel wells both inside and in between the body panels as well as the area behind the wheel wells. On the right side where the spare wheel goes and on the left behind the cargo box. I lined the inside of the quarter panels all the way down and on the inside panel just on the other side of the tail pipe. It made a noticeable difference on interior noise. Your Auto Trim Store sells the matting for $5/yard and I used spray adhesive to tack it on. I am amazed the difference it made. The exhaust tone is much softer.

89gta383

iTrader: (5)

You ever consider the dynomax muffler with the flap inside to divert exhaust gas through the muffler at idle and light cruise? If they had this muffler in a 4" I would buy it.

http://www.summitracing.com/parts/wlk-17157/overview/

Not sure how much flow/power I would lose going from 2 3 inch y-pipes to a single 4 inch pipe to a 3" muffler vs 2 3 inch y-pipes to a single 4 inch pipe to a single 4 inch muffler.

midias

Put mine here worked great
https://www.thirdgen.org/forums/showthread.php?t=717380&goto=newpost

antman89iroc

I considered that muffler at first as well as making a flap in the tail pipe with the same design. In the end it all depends in how much flow your engine really needs vs how quiet you want the system. For me the combo with 3 1/2 pipe and 3 mufflers and a resonator have me the theoretical flow I needed and is quiet enough. Also your rear end gearing plays a role. Most exhaust seen to resonate unpleasantly around 1600-1800 rpm when loaded. My 3.70 gear cruises at 2000+ in overdrive so I avoid the drone. I could have gone with a 3" system if I didn't plan for nitrous use. Most engines will do good with 3 or 3 1/2" single pipes.

tb3

would a resonator or glass pack be quieter than the stock catalytic converter?

I recently installed a dynomax super turbo exhaust. Fit was awesome, but its way to loud for me. Going down the highway you have to raise your voice to have a conversation, and turn the radio up pretty loud.
I tried it first by not installing the cat, but it was crazy loud, I put the cat back on and I'd really like to quieten it down some more.
I have a test pipe I can weld a straight-through muffler or glass pack or resonator into, if its going to be quieter than the stock cat.

midias

I dont know if the overall volume will be less but it is my experience that a resonator reduces drone more than a cat. Put in the longest one you can fit. Using the cat location is a decent idea. It is my experience the closer to the engine straight through mufflers are the quieter that they make the tone. You \have two choices, louvered and perforated. The louvered will do more to reduce sound but dont flow as well.

Personally I like dynomax race bullets as resonators if salt is not an issue they are perforated. For my daily driver I used silverline stainless resonators. If you want louvered summit has them dirt cheap under their house brand.

89gta383

iTrader: (5)

I went out and measured my current set-up. I have the 4 inch ultra-flow 17537 muffler (27 inches long) now under the gas tank. I have about 27-28 inches in the intermediate pipe before the rear axle to put another 4 inch muffler to try and quiet down this system. http://www.dynomax.com/mufflers/ultr..._diameter1=146

I was thinking I would put the 17225 21 inch long ultra-flow muffler before the axle. I don't really have space for any race bullets in the y-pipe anywhere without hitting the bottom of the car.

Does anyone know of anymore mufflers/resonators that would keep the flow of the system high but reduce the sound level more than the 17537 and 17225 mufflers?

midias

You could try their 4" race bullet. It might not reduce sound as much but it is 5" in diameter vs 6

http://www.dynomax.com/race-series-b...und-24253.html

89gta383

iTrader: (5)

I am trying to get max sound reduction, so I would think a "muffler" vs a "race bullet" the muffler would win?

http://www.summitracing.com/parts/bor-40948

Above is a 4inch 4.5 diameter oval muffler vs the 6 inch diameter round ultra flow which would fit under the car better. Price is twice as much also but I am short on space.

I can re-measure my y-pipe and see if the race bullet in 3inch could go somewhere in each y-pipe after the header collector maybe.

antman89iroc

I spoke with a tech at Dynomax when building my system. I will summarize what I heard. Essentially, all their straight through mufflers are the same whether they're called "race" or not. Their ability to reduce sound pressure is dependent on their length and the amount of space between the perforated core and exterior housing and whether they have packing. Some of the "race" mufflers do not have any packing at all so I would classify them as "resonators". For example a 3 1/2ID muffler with 4OD probably doesn't have any packing. A 3 1/2ID with 5OD would have 3/4 of packing all the way around where a 3 1/2ID with 6OD would have 1 1/4 of packing all the way around and "muffle" better. Get it? So, get the longest muffler with the largest external OD that will fit and that is the best you can do.

The best I remember is the welded mufflers typically have the largest external OD and the "bullet" mufflers are smaller. The "race bullet" are just bullet style mufflers, what I would call "cherry bomb" style. That's really the only difference.

I think the best strategy is to place a muffler in the stock location (for a single exhaust) and if it's too loud add one just in front of the axle and if it's still too loud add more in the head pipes close to the engine.

89gta383

iTrader: (5)

got it thanks.

But that begs the question, is the 4 inch ultra-flow muffler that is 16 inches long and 6 inches round better than the 4 inch borla that is 16 long x 4.5 thick x 7.88 wide ?

The ultra-flow has 2 inches of sound deadening material around it (4 in inlet minus 6 inch round muffler case) vs the borla with maybe 3.5 inches of packing material (4 in inlet oval minus 7.8 inch max width of case on 2 sides only).

antman89iroc

Yeah the comparison only works within the Dynomax brand. Borla may have different hole patterns, packing materials etc. I almost added the comment regarding oval mufflers, Dynomax tech told me there wasn't a measurable difference in their round vs oval mufflers. When I pointed out that on their site the oval was listed as "quieter" than the round he said while theoretically true it wasn't measurable. ?? Basically I used the largest, longest straight through muffler that would fit.

Another comment I have is in regard to perceived value. Borla mufflers cost more, have nicer finishes and likely better materials. They would probably last longer because of this. Many users say they sound better. If two exact vehicles with exactly the same size and type of mufflers were fitted, I bet it would be difficult to tell which one had a Borla and which one had a Dynomax. Maybe I'm wrong but often the difference is the type and construction of the muffler, not cost.

As long as the average insulation thickness is about the same I think round vs oval would sound the same, it's a fitment issue. In some installations the oval allows the correct offsets and gives the exhaust the "right" look. As long as you have room, I think the round is the way to go. The oval style may improve ground clearance in some instances.

89gta383

iTrader: (5)

Just an update:

I just put the #17225 21 inch long dynomax ultra-flow muffler before the axle and I can't tell a difference in sound what so ever. Car sounds the same. I don't really have space for 2 3" mini bullets in the mufflex y-pipe without taking it to a muffler shop and having them cut and weld them in on a lift.

I might try a bigger muffler under the gas tank or even a 4 inch bullet in the tailpipe after the muffler if I can fit it.

ragtopday_z28

Do you have a drone when cruising around? Did the additional muffler change that in any way? I'm thinking about a 4" system with the Dynomax 17537 muffler as well. I'm really not too concerned with how loud it is (within reason), but I can't stand the drone that my Flowmaster has right now.

89gta383

iTrader: (5)

I had a slight drone at 14-1600 in overdrive with the one muffler, but nothing as bad as a flowmaster, that was the worst I ever had.

I added this extra muffler but didn't drive it, only moved it around in the driveway, so I don't know if the drone is gone, header is off to fix an leak and I am changing cams, so won't start it for a while now.

DiabloWS6

iTrader: (8)

As said by magnaflow exhaust engineer a straight thrugh perforated with a steel wool packing is as close to runing a straight pipe with out losing little back pressure. The resonator takes that unwanted rasp as most members here like using Flowmaster and gives that pirate noise (rrrrrrr) at the end of the exhaust deceleration. Chambered exhaust sacrifices some flow because of the travel it has to make and is not straight through path...that is why our stock cross flow is such a poor design. I like how the slp totl is designed i have one. Well all all of the post prior to mine are correct. Find the youtube on magnaflow exhaust engineering so much good info on exhaust.