Has anybody installed side branch resonators on their car. I recently got a new exhaust and was surprised that there was that much drone. So I looked into some options and other people have done this.

http://i718.photobucket.com/albums/w...HKSchamber.jpg

The resonators work by diverting part of the sound from the tailpipe into the resonator, where it travels down the resonator, hits the end of the pipe, reflects back down the pipe, and re-enters the tailpipe. then it re-enters the tailpipe 180 degrees out of phase and partially cancels the sound in the tailpipe.

There are certain dimensions of the resonator you have to get to work properly (physics in phase out of phase cancellation. ) The ideal length is 1/2 the tailpipe length, and same diameter as the exhaust. It makes sense, any body have this done or can chime in?

 

I read a little bit about it a while back. It's not as simple as half the tailpipe length. There is a formula but I forget what it is exactly. The frequency in which your drone occurs is what you need to take into account. I'm thinking about doing this little mod too

 

This is exactly what I've done to my Z. Highly recommended, it may take a couple ofntries to get the right length


More info in my thread:

http://www.300zxclub.com/showthread.php?t=202092

 

I cant log in, because I'm not a member. And yeah i read about the formula, if you do it right you get the quietist sound, the more off you are of the formula, the less is bounces back and less quiet you get. I was hoping somebody could tell me the measurements i needed for the M2 exhuast.

 

How about a twin-loop muffler instead? The above HKS pic makes me believe that you are removing the benefit of having a free-flowing straight-through exhaust system with no bottlenecks or reversions.

 

Woops didn' know you need to be a member. In regards to sound loudness is still there, it's just that drone has moved out of cruising rpm. You get the best of both worlds because performance loss is negligible, sound doesn't change, but reduces/eliminates drone. Factory honda S2000 and many high end BMW/370Z aftermarket systems comes with this. You can theoretically come up with a number on paper but only way to find out is to fabricate longest pipe that fit w/o being seen and cut/cap until you find the perfect length to get rid of your drone. Luckily it only took two tries for me.

Pics from my thread

E90 BMW

MKIII turbo

370Z

 

Man, I really want to do this, but dont have the resources to just trial and error it. Would an exhaust shop know how to do it if I took it to them? And my concern is, if you have the wrong length theoretically can the sound waved be constructive instead of destructive and become louder? Is there a place in specific to put the side branch resonator?

 

You can always switch to the F sport exhaust. Drone starts at 80 and even then its quiet

 

I wish!! Im a college kid, and 1000$ isnt exactly just laying around for me. Care to donate? lol. I got the m2, but regretting it, wishing i would have gotten the tanabe. I might just take it off and sell it. Its only been on for 5 days. And the drone at 65mph is loud. Especially for how quiet the exhaust is on the outside.

 

Exact problem I had. I had to speed up and maintain above 75mph for quiet cabin. Now I still have drone at certain speeds under 55mph but by 60-65mph it's stock quiet. First time at shop cost me $130 then 2nd time $50(to add 5'' on each side)for total $180, not bad I think.

 

ya i found the drone of m2 is quiet damn loud!

 

easier way.......get silencers

 

spelling matters...LOL

 

Hahaha^ and silencers? I know they make them for the HKS, but i dont think they make them for the m2, or are there universal ones? i wish i could see the before and after sounds of an exhaust with the side branch resonators and without.

 

ya i meant for the hks......i've heard it in person and it's still as loud and deep of a growl outside but inside the cabin it's much much better