Resonance, where does it come from?
Le Mans Master
Joined: Dec 2006
Posts: 5,139
Likes: 482
From: H-Town Texas
Does anyone have any pics of an LT1/4 muffler cut open like the corsa muffler? I would love to see the difference? How about the center resonator?
Maybe if we get as many pics of mufflers cut open and peoples experiences we can see what could possibly work...
I think the Vettes shape, the material it uses (fiberglass), the engine tune/gears, and the location of the exhaust have to also do a lot with the resonance. Maybe if the pipes were separated they wouldnt act as tuning forks. I am not sure, just throwing some ideas out there.
Exhaust flow has a lot to do with it because when you add restriction it usually cuts down the resonance. Like stated above its probably caused by sound waves cancelling but if that is so then how do you make a free flowing muffler that is low on resonance?
Maybe if we get as many pics of mufflers cut open and peoples experiences we can see what could possibly work...
I think the Vettes shape, the material it uses (fiberglass), the engine tune/gears, and the location of the exhaust have to also do a lot with the resonance. Maybe if the pipes were separated they wouldnt act as tuning forks. I am not sure, just throwing some ideas out there.
Exhaust flow has a lot to do with it because when you add restriction it usually cuts down the resonance. Like stated above its probably caused by sound waves cancelling but if that is so then how do you make a free flowing muffler that is low on resonance?
Thread Starter
Pro
Joined: Apr 2001
Posts: 744
Likes: 13
From: Lenoir City TN
This is the exact system I am running. I am using the Magnaflow dual in dual out, as I tried the Dynamax, but it was too wide to install. I personally really like the sound. Magnaflow puts a high flow x-pipe along with sound damping material in this muffler, which really helps to give a nice tone. Yes, it can be loud, but hearing your engine is not what I consider resonance. The trick is to make sure the tips are about 1/2" beyond the bumper and point slightly downward. This keeps the bulk of the sound from the cabin.
Instructor
Joined: Feb 2009
Posts: 248
Likes: 1
From: SF East Bay CA
This topic has indeed been worked, but a well-informed discussion is always worthwhile. A few additional thoughts:
1) I, too, was wondering why Mustangs sound good (let's be honest, they do). The effect of firing order on exhaust pulses is apparently a key factor.
2) Interesting to hear that the stock LT resonator has perforated tubing and allows some flow between sides. This indicates at least some balancing like an X pipe.
3) The H pipe GM added to LT4s behind the resonator is noteworthy, since it was presumably done to address sound, performance and cost. Does it perhaps suggest benefits for both the resonator (noise control) and the crossover (performance)? Just a thought; I sure wish someone could provide the background.
1) I, too, was wondering why Mustangs sound good (let's be honest, they do). The effect of firing order on exhaust pulses is apparently a key factor.
2) Interesting to hear that the stock LT resonator has perforated tubing and allows some flow between sides. This indicates at least some balancing like an X pipe.
3) The H pipe GM added to LT4s behind the resonator is noteworthy, since it was presumably done to address sound, performance and cost. Does it perhaps suggest benefits for both the resonator (noise control) and the crossover (performance)? Just a thought; I sure wish someone could provide the background.
Le Mans Master
Joined: Dec 2006
Posts: 5,139
Likes: 482
From: H-Town Texas
As far as resosnance, all I hear is motor. Cruising it has a rumble to it and at wot it screams pretty loud. Like I said, I am not sure what the exact definition of resonance is, I think perhaps it depends on the person. It seems like sometimes folks want their cars to sound loud and mean on the outside and be Cadillac quiet on the inside, and in disappointment, call it resonance when in fact, they're just hearing the exhaust giving them what they paid for. IMHO
As far as I'm concerned, and been told by others that this set up sounds like a SBC should sound like. I just know I really like it, going on it's fourth year now. I saved my stock mufflers just in case, but they've been gathering dust ever since.
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
This topic has indeed been worked, but a well-informed discussion is always worthwhile. A few additional thoughts:
1) I, too, was wondering why Mustangs sound good (let's be honest, they do). The effect of firing order on exhaust pulses is apparently a key factor.
2) Interesting to hear that the stock LT resonator has perforated tubing and allows some flow between sides. This indicates at least some balancing like an X pipe.
3) The H pipe GM added to LT4s behind the resonator is noteworthy, since it was presumably done to address sound, performance and cost. Does it perhaps suggest benefits for both the resonator (noise control) and the crossover (performance)? Just a thought; I sure wish someone could provide the background.
1) I, too, was wondering why Mustangs sound good (let's be honest, they do). The effect of firing order on exhaust pulses is apparently a key factor.
2) Interesting to hear that the stock LT resonator has perforated tubing and allows some flow between sides. This indicates at least some balancing like an X pipe.
3) The H pipe GM added to LT4s behind the resonator is noteworthy, since it was presumably done to address sound, performance and cost. Does it perhaps suggest benefits for both the resonator (noise control) and the crossover (performance)? Just a thought; I sure wish someone could provide the background.
Last edited by Tom400CFI; May 28, 2010 at 07:30 PM.
Melting Slicks
Joined: Feb 2005
Posts: 3,204
Likes: 4
From: Midland Georgia
St. Jude Donor '06
The Magnaflow has 2.5" inlets/outlets. The x-pipe inside is pretty large however. They do have a 3" inlet/outlet available as well. But this thing seems to flow really well.
As far as resosnance, all I hear is motor. Cruising it has a rumble to it and at wot it screams pretty loud. Like I said, I am not sure what the exact definition of resonance is, I think perhaps it depends on the person. It seems like sometimes folks want their cars to sound loud and mean on the outside and be Cadillac quiet on the inside, and in disappointment, call it resonance when in fact, they're just hearing the exhaust giving them what they paid for. IMHO
As far as I'm concerned, and been told by others that this set up sounds like a SBC should sound like. I just know I really like it, going on it's fourth year now. I saved my stock mufflers just in case, but they've been gathering dust ever since.
As far as resosnance, all I hear is motor. Cruising it has a rumble to it and at wot it screams pretty loud. Like I said, I am not sure what the exact definition of resonance is, I think perhaps it depends on the person. It seems like sometimes folks want their cars to sound loud and mean on the outside and be Cadillac quiet on the inside, and in disappointment, call it resonance when in fact, they're just hearing the exhaust giving them what they paid for. IMHO
As far as I'm concerned, and been told by others that this set up sounds like a SBC should sound like. I just know I really like it, going on it's fourth year now. I saved my stock mufflers just in case, but they've been gathering dust ever since.
Sounds like you have no resonance. There is a definitive different between a lovely SBC exhaust rumble and resonance. Your exhaust is set up properly. The B&B that I had was a 3" inch stainless steel version for the LT1. It was the first generation that B&B produced. In my car in 6th at cruise between 1500 and 2000 rpm the cockpit was invaded by resonance. With the windows up in the car it was intolerable. Lower the windows or drop it down into 5th and the nice exhaust rumble returned.
When you experience resonance you will know it because after about 46 minutes you will need tylenol for the headache it will give you.
Safety Car
Joined: Sep 2000
Posts: 3,524
Likes: 4
From: Hinckley Ohio
Sounds like you have no resonance. There is a definitive different between a lovely SBC exhaust rumble and resonance. Your exhaust is set up properly. The B&B that I had was a 3" inch stainless steel version for the LT1. It was the first generation that B&B produced. In my car in 6th at cruise between 1500 and 2000 rpm the cockpit was invaded by resonance. With the windows up in the car it was intolerable. Lower the windows or drop it down into 5th and the nice exhaust rumble returned.
When you experience resonance you will know it because after about 46 minutes you will need tylenol for the headache it will give you.
When you experience resonance you will know it because after about 46 minutes you will need tylenol for the headache it will give you.
I too had the original 3" B&B.....the other option is cruise about 90mph...earplugs was the only thing I ever found that worked
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Safety Car
Joined: Sep 2000
Posts: 3,524
Likes: 4
From: Hinckley Ohio
This topic has indeed been worked, but a well-informed discussion is always worthwhile. A few additional thoughts:
....
3) The H pipe GM added to LT4s behind the resonator is noteworthy, since it was presumably done to address sound, performance and cost. Does it perhaps suggest benefits for both the resonator (noise control) and the crossover (performance)? Just a thought; I sure wish someone could provide the background.
....
3) The H pipe GM added to LT4s behind the resonator is noteworthy, since it was presumably done to address sound, performance and cost. Does it perhaps suggest benefits for both the resonator (noise control) and the crossover (performance)? Just a thought; I sure wish someone could provide the background.
FWIW I think part of the problem is the 3 inch and secondly I think the stainless steel just might resonant a lot better than aluminized steel
Instructor
Joined: Feb 2009
Posts: 248
Likes: 1
From: SF East Bay CA
http://www.bangshift.com/blog/Chart-...rtesy-MSD.html
"As an example, the well-known Chevrolet Small-Block engine has cylinders 1-3-5-7 on the left hand side of the car, and 2-4-6-8 on the other side, and uses a firing order of 1-8-4-3-6-5-7-2. [1] Note that the order alternates irregularly between the left and right banks; this is what causes the famous 'burbling' sound of this type of engine. [2]
In most Audi and Ford V8 engines cylinders 1-2-3-4 are on the right hand side of the car, with 5-6-7-8 are on the left.
This means that GM LS V8 engines and Ford Modular V8s have an identical firing pattern despite having a different firing order." Wikipedia
Race Director
Joined: Nov 2003
Posts: 12,221
Likes: 446
From: Overland Park Kansas
2020 Corvette of the Year Finalist (appearance mods)
C4 of Year Winner (appearance mods) 2019
Where does resonance come from? Well,,,let's examine the word.
RE-SON-ANCE
RE = repeated (as in over and over)
SON = root of the word "sonic"
ANCE = ants (mis-spelled of course!)
So, it's the sound of ants crawling around your car over and over. Some might use bug-spray as the cure. Or, you can run them off with a LOUD exhaust!
(Just some light-hearted fun for the holiday!)
RE-SON-ANCE
RE = repeated (as in over and over)
SON = root of the word "sonic"
ANCE = ants (mis-spelled of course!)
So, it's the sound of ants crawling around your car over and over. Some might use bug-spray as the cure. Or, you can run them off with a LOUD exhaust!
(Just some light-hearted fun for the holiday!)
Thread Starter
Pro
Joined: Apr 2001
Posts: 744
Likes: 13
From: Lenoir City TN
Team Owner
Joined: Sep 2003
Posts: 20,179
Likes: 673
From: Freedom is never more than one generation away from extinction.
St. Jude '03 thru '24
"Resonance, where does it come from?"
From the rolling ghetto blasters we hear driving on the streets.
Its also the sound of the moldings rattling on any car within a 50 foot radius of said ghetto blaster.
Pro
Joined: Jun 2006
Posts: 508
Likes: 1
From: Miami Florida
Here's what I did, and I have no resonance problems whatsoever. First, I removed all the oem parts in the exhaust system. Then I installed a set of Hedman long tube headers with 3 inch collectors. I then ran a straight pipe from each side of the engine to the center of the car and into a Magnaflow two tube resonator and out the other end with a straight pipe on each side to a Corsa muffler. The Magnaflow resonator fits just perfect into the place where the cat used to be. The sound while driving normal is well.. normal. I can hear the radio and talk at a normal level. When I go to WOT, the sound is awesome! No overload or resonance. I couldn't be happier.
Steve
Steve
3rd Gear
Joined: Aug 2009
Posts: 3
Likes: 0
I have stock manifolds, 2.5 inch pipes, 2 stainless cats, 2 chambered mufflers at the rear with large (2x8) stainless tips. All completly seperate, no H or X pipe. The sound is awesome at idle and WOT, but at cruising speeds the resonance is horrible even with the windows down. I was thinking of of dividing the system into thirds, putting one H pipe at the rear of the trans and one near the rear suspension. I'll make it look like damn ladder if it fixes it. Hoping that the problem is the complete seperation of the 2 pipes. I like the Dynomat idea too, it's going on whether the H pipes work or not.
Advanced
Joined: Jun 2010
Posts: 58
Likes: 0
From: Bowling Green Ky
TRANS03,you might think about putting glass packs in..I have a true dual magnaflow system and the same problem until I added the glass packs,makes it a little quieter but well worth it and I'm only into the exhaust about $525 in all..something to think about
Advanced
Joined: Jun 2010
Posts: 58
Likes: 0
From: Bowling Green Ky
TRANS03,mine were put about center of the exhaust side by side...keep in mind I have no cats so the reason I added the glass packs was with hopes of getting rid of an irritating fluttering sound out the tips so it was either new cats at $125ea. or glass packs at $40ea...it was a very nice bonus when I started down the road and the resonance was dramatically reduced as well..remember too that the longer the glass pack the quieter the sound...good luck
