Side Branch Resonator
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Joined: Jun 2010
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Side Branch Resonator
Has anyone added a Side Branch Resonator to their aftermarket exhaust to reduce drone?
The OEM exhaust has this, just wondering if I can get the same length of dead end pipe to takeout the drone during 3~4k RPM on my aftermarket exhaust
Here is a good read on this topic...
http://www.enoisecon...arrier_wall.pdf
The OEM exhaust has this, just wondering if I can get the same length of dead end pipe to takeout the drone during 3~4k RPM on my aftermarket exhaust
Here is a good read on this topic...
http://www.enoisecon...arrier_wall.pdf
Joined: Jan 2003
Posts: 2,184
Likes: 95
From: Granville OH
In a former life, I used to work with an exhaust manufacurer in the design of exhaust systems, and it was interesting to learn why exhaust systmes had certain characteristics, which explains the OEM design.
An exhaust system is "tuned" to the engine and vehicle. The length of the sections of the exhaust tube as well as the total volume of the exhaust system determines the frequencies at which resonation (harmonic frequency) occurs. The trick is to design an exhaust system with harmonic frequencies outside the operating range of the vehicle. For a car with an engine designed to redline at 9,000 RPM, that's no easy task.
To break up the large section between the cat and the split to the mufflers, Honda put a standard resonator right in the middle. Not only does that break up the length of the tube, but it adds significant volume to the exhaust system which changes the harmonic pitch. Honda could have tuned the exhaust system by tweaking the standard resonator but that takes countless tweaks and test cycles, resulting in excessive development cost. To get around this, they add the Helmholtz resonator. Then by simply making this pipe shorter or longer, they can get the precise volume in the exhaust system by just changing the length of this appendage. Once they figure out how long to make it, they make all of them the same length.
Therefore if you want to add a Helmholz resonator to your aftermarket exhaust system, you would just be guessing how long to make the appengage. You could concoct a cup-over-a-tube setup and play around with the length until the resonant frequency goes away - kind of like a trombone - then weld it in place when you get the right length. But if you think you're just going to weld a tube on the side of an aftermarket exhaust system and hit the optimum size, you're kidding yourself.
An exhaust system is "tuned" to the engine and vehicle. The length of the sections of the exhaust tube as well as the total volume of the exhaust system determines the frequencies at which resonation (harmonic frequency) occurs. The trick is to design an exhaust system with harmonic frequencies outside the operating range of the vehicle. For a car with an engine designed to redline at 9,000 RPM, that's no easy task.
To break up the large section between the cat and the split to the mufflers, Honda put a standard resonator right in the middle. Not only does that break up the length of the tube, but it adds significant volume to the exhaust system which changes the harmonic pitch. Honda could have tuned the exhaust system by tweaking the standard resonator but that takes countless tweaks and test cycles, resulting in excessive development cost. To get around this, they add the Helmholtz resonator. Then by simply making this pipe shorter or longer, they can get the precise volume in the exhaust system by just changing the length of this appendage. Once they figure out how long to make it, they make all of them the same length.
Therefore if you want to add a Helmholz resonator to your aftermarket exhaust system, you would just be guessing how long to make the appengage. You could concoct a cup-over-a-tube setup and play around with the length until the resonant frequency goes away - kind of like a trombone - then weld it in place when you get the right length. But if you think you're just going to weld a tube on the side of an aftermarket exhaust system and hit the optimum size, you're kidding yourself.
Thread Starter
Joined: Jun 2010
Posts: 779
Likes: 0
In a former life, I used to work with an exhaust manufacurer in the design of exhaust systems, and it was interesting to learn why exhaust systmes had certain characteristics, which explains the OEM design.
An exhaust system is "tuned" to the engine and vehicle. The length of the sections of the exhaust tube as well as the total volume of the exhaust system determines the frequencies at which resonation (harmonic frequency) occurs. The trick is to design an exhaust system with harmonic frequencies outside the operating range of the vehicle. For a car with an engine designed to redline at 9,000 RPM, that's no easy task.
To break up the large section between the cat and the split to the mufflers, Honda put a standard resonator right in the middle. Not only does that break up the length of the tube, but it adds significant volume to the exhaust system which changes the harmonic pitch. Honda could have tuned the exhaust system by tweaking the standard resonator but that takes countless tweaks and test cycles, resulting in excessive development cost. To get around this, they add the Helmholtz resonator. Then by simply making this pipe shorter or longer, they can get the precise volume in the exhaust system by just changing the length of this appendage. Once they figure out how long to make it, they make all of them the same length.
Therefore if you want to add a Helmholz resonator to your aftermarket exhaust system, you would just be guessing how long to make the appengage. You could concoct a cup-over-a-tube setup and play around with the length until the resonant frequency goes away - kind of like a trombone - then weld it in place when you get the right length. But if you think you're just going to weld a tube on the side of an aftermarket exhaust system and hit the optimum size, you're kidding yourself.
An exhaust system is "tuned" to the engine and vehicle. The length of the sections of the exhaust tube as well as the total volume of the exhaust system determines the frequencies at which resonation (harmonic frequency) occurs. The trick is to design an exhaust system with harmonic frequencies outside the operating range of the vehicle. For a car with an engine designed to redline at 9,000 RPM, that's no easy task.
To break up the large section between the cat and the split to the mufflers, Honda put a standard resonator right in the middle. Not only does that break up the length of the tube, but it adds significant volume to the exhaust system which changes the harmonic pitch. Honda could have tuned the exhaust system by tweaking the standard resonator but that takes countless tweaks and test cycles, resulting in excessive development cost. To get around this, they add the Helmholtz resonator. Then by simply making this pipe shorter or longer, they can get the precise volume in the exhaust system by just changing the length of this appendage. Once they figure out how long to make it, they make all of them the same length.
Therefore if you want to add a Helmholz resonator to your aftermarket exhaust system, you would just be guessing how long to make the appengage. You could concoct a cup-over-a-tube setup and play around with the length until the resonant frequency goes away - kind of like a trombone - then weld it in place when you get the right length. But if you think you're just going to weld a tube on the side of an aftermarket exhaust system and hit the optimum size, you're kidding yourself.
Posted too early. Found the info. after an extensive search:
Distance from cat to centre of pipe: Stock 240mm, Amuse 220mm
Length: Both 150mm
Diameter: Stock 45mm, Amuse 55mm.
Location: Is similar both on the Amuse and on stock pipe. Guess that is the best place to put it.
Distance from cat to centre of pipe: Stock 240mm, Amuse 220mm
Length: Both 150mm
Diameter: Stock 45mm, Amuse 55mm.
Location: Is similar both on the Amuse and on stock pipe. Guess that is the best place to put it.
https://www.s2ki.com/s2000/topic/510...or-dimensions/
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