Ok, I've been obsessing over exhaust for god knows how long, because I was deathly afraid of buying an exhaust system that made my car sound like something attractive to a chipmunk. After poring over tons of material, I finally bought my exhaust.
I've had my HKS hiper for about a full week and am starting to wonder what it'll sound like in a few months. When I first drove the car, it was very deep, and as teh piping grew hotter, it got louder, and more deep. I was pretty pleased with the sound, although it is a tad bit loud for my tastes.
After a week or so, I'm starting to hear some changes. After driving for more than 20 mins or so, the piping gets really hot, and the sound begins to change. Now there's a slight buzz in the muffler. When this started, naturally, I freaked out. I did NOT want my car to sound like a lawnmower, or worse . . . a honda.
My point is coming up, so bear with me.
Lets pretend this problem gets worse. This buzzing persists. It is still deep, but at around 1.2k to 2.5k the buzzing is the worst, and drops off at higher rpms.
My questions are these: what is causing this "buzzing"? and how can it be fixed?
My theory is that there are not enough gasses being produced by the motor, so when they reach the large muffler they "bounce around" causing turbulence and noise. So, if I could find a way to make my motor create more gasses (i.e. add more peformance parts, tune it, increase compression) would the sound disappear?
I've been rambling on, so you guys tell me what you think.
Thanks,Nick.
Why exhaust sounds like it does. My theory . . . please input.
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quiksilvia
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I have the exact same problem with my exhaust. This occured right after I installed my header. It sounded deep and smooth before the header but when I installed the header, it started to buzz and zing around 2500-5000 RPM. I hate it cuz my car sounds like a civic. I blame the damn header because I've heard of other cars having the same problem! Hope this helped...anyone whith this type of experience, please speak UP!
MIKEL240 wrote:I have the exact same problem with my exhaust. This occured right after I installed my header. It sounded deep and smooth before the header but when I installed the header, it started to buzz and zing around 2500-5000 RPM. I hate it cuz my car sounds like a civic. I blame the damn header because I've heard of other cars having the same problem! Hope this helped...anyone whith this type of experience, please speak UP!
in regards to the different pitching of the exhaust after header install, the materials it is constructed of and even the thicknesses of those materials make a difference in sound. i changed my stock cast SR manifold out for a stainless equal length and it made the car higher pitched due to the resonant nature of stainless steel. cast manifolds absorb and dissipate a lot of the sound as it exits the engine. any full stainless exhaust system will sound "buzzy" at certain rpms.
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AZhitman
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Well, there's another theory or two.
One has to do with the size of the exhaust - the trend towards bigger diameter piping is couterproductive. Looks cool, but unfortunately is IS cool - and that's the problem. Exhaust gases need to stay as hot as possible to facilitate evacuation of the pipes. Too large a diameter, and the gases cool down, thereby slowing down and hindering expulsion.
The other possibility is that your system, as a mass-produced system, is NOT specifically tuned for the application. Believe it or not, very few companies actually invest the time and effort to achieve peak power production since their bottom line is more important. Often, the system that creates the most power also looks the worst - and we all know THAT won't sell. So you may have a system with a muffler that is poorly-suited for your application (but looks really good).
Does your catback have a resonator? Definitely a MUST if you have a header. Steer clear of any systems with a screw-in "silencer" - you may as well retain the stock system instead.
One has to do with the size of the exhaust - the trend towards bigger diameter piping is couterproductive. Looks cool, but unfortunately is IS cool - and that's the problem. Exhaust gases need to stay as hot as possible to facilitate evacuation of the pipes. Too large a diameter, and the gases cool down, thereby slowing down and hindering expulsion.
The other possibility is that your system, as a mass-produced system, is NOT specifically tuned for the application. Believe it or not, very few companies actually invest the time and effort to achieve peak power production since their bottom line is more important. Often, the system that creates the most power also looks the worst - and we all know THAT won't sell. So you may have a system with a muffler that is poorly-suited for your application (but looks really good).
Does your catback have a resonator? Definitely a MUST if you have a header. Steer clear of any systems with a screw-in "silencer" - you may as well retain the stock system instead.
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C-Kwik
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The buzzing is a toned down version of the exhaust pulses from the motor. Try disconnecting the exhaust entirely. You should hear what it sounded like when I had turned on my motor with the turbo removed from the manifold. You can hear very distinct pulses.
The KA is larger than say a B16, so while it can buzz a bit, it should be at a much deeper tone. Teh Civics buzzing around sound the way they do because their motors are smaller. Think of how a motorcycle sounds. Even at low RPM's the tone is high.
If you want to reduce buzzing, you have to use a muffler that will absorb more noise. These canister exhausts(N1 style) are not exactly the best mufflers by function. They flow well. But any straight through perforated core should flow nearly as well. The piping on these N1 stilye systems have less bends and may see a slight advangate, and can also contribute a small amount ot the noise level. Less bends means less turbilence. Less turbulence means less noise cancellation.
The KA is larger than say a B16, so while it can buzz a bit, it should be at a much deeper tone. Teh Civics buzzing around sound the way they do because their motors are smaller. Think of how a motorcycle sounds. Even at low RPM's the tone is high.
If you want to reduce buzzing, you have to use a muffler that will absorb more noise. These canister exhausts(N1 style) are not exactly the best mufflers by function. They flow well. But any straight through perforated core should flow nearly as well. The piping on these N1 stilye systems have less bends and may see a slight advangate, and can also contribute a small amount ot the noise level. Less bends means less turbilence. Less turbulence means less noise cancellation.
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AZhitman
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All correct except: The N1 style flows LESS. Hard to believe, but true.
Too much open space. The best-flowing (and sounding) mufflers operate on the principle of REFLECTION whereby the exhaust pulses reflect off an internal barrier backwards into the canister, cancelling out the following pulses - but small enough to be evacuated by thermal energy...
BTW, turbulence is not always good for noise reduction either. Improper "turbulence" contributes to that horrid drone you hear on the freeway at certain RPM's in certain cars....
Too much open space. The best-flowing (and sounding) mufflers operate on the principle of REFLECTION whereby the exhaust pulses reflect off an internal barrier backwards into the canister, cancelling out the following pulses - but small enough to be evacuated by thermal energy...
BTW, turbulence is not always good for noise reduction either. Improper "turbulence" contributes to that horrid drone you hear on the freeway at certain RPM's in certain cars....
just took my car out for its first spin with my new exhaust (RS*R GT-II 80mm piping) my car is pretty much stock enginewise but im gonna be turboing soon so i needed something that could flow well. its sounds deep and nice but it is very loud. my friend who was with said it wasnt that bad but im not trying to grab that much attention. also i started the car with no exhaust on it and it sounded very similar to what my new exhaust sounds (both were loud and deep). keep in mind that this is without the silencer which i will be putting in tomarrow.
Supafly wrote:in regards to the different pitching of the exhaust after header install, the materials it is constructed of and even the thicknesses of those materials make a difference in sound. i changed my stock cast SR manifold out for a stainless equal length and it made the car higher pitched due to the resonant nature of stainless steel. cast manifolds absorb and dissipate a lot of the sound as it exits the engine. any full stainless exhaust system will sound "buzzy" at certain rpms.
I totally agree with what you are saying! I have many people tell me that the header is causing the noices to vibrate instead of obsorbing it. I am considering putting back my stock manifold just for the sole purpose of eliminating that nasty buzzing and zinging sound! Anyone else with this same problem, please SPEAK UP!
Mikel, why not have a competent custom exhaust shop flange the exhaust system for a resonator and install one? Look at dynomax for a company that makes resonators, you can find em' through http://www.summitracing.com . I had my exhaust system flanged so that I can swap between cat and resonator, should be rather nice 
Edit: silencer = huge restriction, usually more so than the stock exhaust was. Huge restriction = no good.
Edit: silencer = huge restriction, usually more so than the stock exhaust was. Huge restriction = no good.
It should actually help cut down on the "buzzyness" of the exhaust because in effect, its just another muffler in the system, albeit a straight through one. It also doesn't represent a significant cause of turbulence in the system, and absorbes some of the sound. As a rule of thumb, resonators are recommended whenever there is more than a 6' run of piping before a muffler in the system. Be forwarned though, its not always cheap to have the job done right, to flange my cat and resonator so they could be swapped between was about 150 bucks because of the cost of GOOD flanges, gaskets, and labor. The resonator shouldn't cost more than 30 bucks or so though, and I just remembered that http://www.jegs.com has a better price on the one I used (dynomax somethin) than summit did.