^^ the large Tube above the pipe is secondary resonator...it sits above the exhuast.

 

Does air just go into that resonator and bounce back into the exhaust? Doesn't seem like a good design at first glance. Then again, I have no knowledge of those exhausts at all.

 

The official name of the upper canister is a "branch tuner or Hemholtz chamber". In all honesty, this is kind of a gimmick. The intention of a tuning can like this is to remove a specific period of unpleasent droaning noise. The placement of the can in the system, the diameter of the primary branch tube, the length of the tube and if the tube is perforated inside the can determines it's effectivity.

HKS put this branch tuner on their system. Then Ningbo Smart made a clone system in China using the same concept. This looks like their work. They simply removed the muffler and welded this thing to a straight pipe. If you cut it off and welded the hole shut, it would be marginally louder.

Sound reduction is done via two methods. Cancellation and absorption (dissapation). Cancellation occurs when like frequencies collide. The cancel out. A branch tuner does just that. By controlling the branch tube diameter and length, you are effectively taking some of the soundwaves and altering the frequency to a higher level. The wave enters the canister and reflects off the end of the tube and goes back into the next incoming wave. If the frequencies are the same, they collide and cancel. But the canister changes diameter and volume. Thus the frequency changes briefly. By the time it reflects, it may hit the incoming wave but the frequencies may not be matching. Cancellation is not as effective as the tuner pipe without the canister on top. Some OE Honda systems had tuner pipes like that that were just a pipe with a plug on the end. (No change in diameter.)

The range that this kind of tuner covers is very limited. In exhaust systems, what we like is the deep (low frequency) sound. The branch tuner hits a narrow band of high frequency. In some cases, it can tune out low frequency when large enough tuner pipes are used. In my guess, this branch tuner is pretty large in diameter. So it is more effective in removing low frequency. (Not what you want taken out.)

Absorption is most effective on high frequency. Honda engines typically produce very high frequency sounds. This is why when a Civic puts on a fart can, it still sounds like a kazoo. To cure high frequency, you need lots of absorption like fiberglass and stainless steel mesh wool. Increased muffler volume (size of the muffler body) helps increase the amount of high frequency absorption. The most common design is a perforated pipe wrapped with stainless steel wool and run through a chamber of injected fiberglass (such as Advantex by Owens Corning or basalt wool.) The stainless wool protects the fiberglass from intense heat or from allowing the brittle fibers from to escape out the tailpipe.

In some cases, resonance frequency may be the cause of droaning noises at interstate speeds. Every object on Earth has a natural frequency. This is the frequency where an object will vibrate. (Like a tuning fork.) Some exhaust systems have a natural frequency low enough to induce cabin droaning noises at normal operating vibration levels. So to remove this noise, you alter the natural frequency of the system by adding a brace in a bend, add a counterweight to the specific modal position in the system or change materials. Altering the design from the OE system completly throws this tuning to the wind. Removing the muffler from the HKS design may fix or cause resonance frequency issues.

Exhaust tuning is a lot of trial and error. You never know exactly what you'll need so you can either start with next to nothing and keep adding till you get what you like or do the reverse and remove components untill it is how you like it.

Sorry for the long explanation. After 17 years of designing exhaust systems, I've seen a lot or strange aftermarket designs. Heck, I hold a patent on a wierd one. Every once in while, a company gets lucky and releases something simple that hits the frequencies just right. This could be such a case but my instincts say no. I certainly would like to hear it in person.

 

The highway drone is ridiculous with my current system - we wear earplugs to and from track events. If this doesn't help, or doesn't help 'enough' there is one other new axle-back with an actual muffler called the Nova.

Thanks for the explanation though - I'm hoping for positive results.

 

I upgraded my exhaust from stock 2.5" with resonators to the available MAZDASPEED 3" with no resonators and single muffler. The exhaust actually got quieter during highway cruising and take off. The resonators made the exhaust so boomy on the inside, after a while it got so annoying and you'd have a headache. My dad warned me before helping me install it, saying "Man..this is a huge exhaust..I don't think you're going to like it". Then we fired it up and were very surprised.

Those canisters just look like they'd interrupt airflow, because it's got nowhere to go but back into the flow of exhaust. Then again, it's so far down the exhaust path, it may not make a difference.

 

I honestly thought my system was loud until I heard yours Steve. When we were at AJ's, we heard you all the way out to the main road. LOL

I think you should consider the clone HKS system unless you drive in the winter. (The clone systems rust easily.) You can pick it up for less than $500 as opposed to multiple cheaper systems that you won't like. I am biased towards the Greddy EVO II system but I selected it based on my experience. Even with that, I still plan to slightly modify it to take out a slight buzz at high RPM.

 

Steve-I don't doubt it man, that thing is loud as HELL...
Looks cool enough I hope it helps you get a more reasonable sound.

Brian-I learned a ton reading that. thx I have no idea about exhaust tuning
P.S. EVO II is the best in my opinion as well for NA applications.

I agree Brian my old EVO with the non res tp's was LOUD, but Steve's was def louder.

 

So GTM Motorsports is asking for a car to use to make a TT install dvd...
Talk me out of asking to pay $7k for this:
http://gtmotorsports.com/product.php...cat=451&page=1

It would be so retarded. :P

 

Talk you out of it? Add the cost of another car to use when stuff breaks...and the cost to fix stuff that breaks.. If you have that covered.. go for it.

 

7K including install / tune? Do eeeettt!!!!!!!

 

The reliability is the thing that makes me think that it's just a retarded waste of money.

 

New wheels, crappy pics!

Varrstoen ES 2.2 matt black finish.
19x9.5 +12
19x10.5 +12

 

^^ Damn sweet wheels!!! I so want all black right now.
Congrats! I bet you can't wait for winter to end!


Lee: Isn't your Z fast enough for you? My approach is do the suspension, wheels, exhaust, brakes and bolt ons while the factory warranty is in place. After it has expired, then go TT.

Reliability does scare me too. I'd feel better doing it if I had a built bottom end and a tuner that knew what they're doing. (Forged)

 

^ I think GTM would be more than capable of doing the install and tune. The only reasons I have not done twins yet is because of reliability, and costs. If I had the money for a built motor, and all the extras for when my engine blows then yes I would do it too.

 

Lee-
No offense I am NOt trying to be a dick here man

you need to learn how to push the car you have NOW, let alone with TT.
Get some instruction and track time under your belt, THEN get the power as you can handle it....

Trust me this goes against EVERYTHING about me, I would do it in a heartbeat.
Then again I drive more with ***** then brains!

Jeez-Those wheels ar Sex by the way!!!
What tire you gonna throw on them??

 

Oops, I wasn't trying to compare GTM to Forged. I was speaking in general. I know a lot about cars and installing parts, but getting them to run their best is an art I do not have.

 

Yeah, the car is fast enough for me.... The only reason why I would consider it is because it's about $3-4k off the normal price. :P Otherwise I would probably never have thought about it.

I'm really just planning on only ever doing bolt-ons. With intake and exhaust I should be around 300 WHP, which I think is pretty great. So now my plan is the stillen g3 and some better pads due to the brake failure horror stories I've read. After that I haven't even thought about mods.

 

Well they came in. The whole motorsports kit. The camera is a lot smaller in person than I thought it was going to be.

 

Sexy wheels.

Woohoo! I can't wait to play with it.

 

Nice ! Congrats. Now show us some of your motorcycle track videos with that camera