Hi, my evo viii 2005 is bone stock. I recently switch from ALL stock exhaust to


-3" HFC from ultimate racing
-Dynomax VT 3" muffler 17957 (https://www.evolutionm.net/forums/ev...y-muffler.html) This is the same recommended by BlueEvoIX, and very good sounding on his car
-There is 2.5" stock piping on the car


Here is the problem: http://www.youtube.com/watch?v=UAxPuihP5yY
I have a big problem from a sound coming from the back of the car, an "Air frequency noise", or a pipe noise
I think my exhaust tip is like 12" because the muffler is so smaller than OEM. I hope this is the problem but I doubt it.
From inside of the car the sound isn't even noticeable. You can just hear it in the rear of the car...

Could the too long muffler tip cause that sound problem??
Is a vibrant ultra quiet resonator would quiet this particular noise?


Thanks for your help guys!!!


Fiy: My car is quieter than stock on the highway with this muffler, so I don't know what is that air pulsing sound...





Edit: Found what was doing this sound: I had the idea to start my car and take a long rod to open the muffler valve. And yes, the air puffing sound is air hitting that valve into the dynomax vt.

-Full open I don't hear air pulsing but I have some deep growl that I don't want on the highway.
-Full close, without me holding it opened, it is a very loud air puffing sound.
-25% opened, a little deep drone/growl and a little air pulsing.

So that's how I'll fix the bad noise. I'll weld a little rod on the valve to avoid it closing completely (20-25% opened). This will make me very happy with that muffler, saving me a lot of money.

 

It's the muffler. Have you seen the design? I believe it has a valve or some pressure-actuated valve in it. It's normal for those kind of mufflers.

If it's a straight-through type of muffler, then it'll be something like this:

http://www.youtube.com/watch?v=fYcqqxL96xg

Btw: I'm running a full 3" tbe with the magnaflow muffler. The video does no justice for the exhaust. lol

 

No, if I open the valve myself, the sound is the same, just louder.
But maybe the valve itself do the sound... Should I take a big chance removing it...

 

Are you referring to like a air pulsing sound similar to a tractor ?

The video seems to be normal. The tractor like air sound is just the exhaust rushing out in pulses. Mine is similar to that as well. I dont have a HFC but I'm running a center muffler.

I'm only guessing here, but it's probably caused from the short distance the exhaust pulse travels before exiting the tubing.

Here is mine, its from a different angle, different camera and distance. That's why it might sound slightly different. But adding more mufflers will mostly change the noise when the flapper is open , in my opinion...

Donwload file:
http://www.neiu.edu/~asaakian/Exhaus...%20exhaust.avi

 

Unless I'm mistaken and miss understanding you? Its an air rushing sound in fast pulses and sounds similar to a tractor, correct?

 

Yes it's that sound but my air pulse seem to be louder than yours...
So the long exhaust tip seems to have nothing to do with that, or maybe....dunno

I'm pretty sure that police will get me for this, that's why it need a setup change

 

Well, from the video its hard to tell how much more pronounced yours is over mine because you have your camera closer to the exhaust path.

You shouldnt have any trouble with the police. Its not really an exhaust sound more of just an air puffing sound. Also your exhaust tip is a little closer to the muffler than mine, not sure how that might affect things.

 

They won't bug you unless it's uber loud. The oval-type mufflers usually draw less attention than the round canisters. If you're worried, you can paint the muffler and piping with some high temp paint. The pic below is my setup. It's a hell lot louder than your setup for sure and it's not drawing any unnecessary attention. You'll be fine.

 

the air pulsing is pretty strong, believe me it's VERY annoying, i'm ordering a vibrant ultra quiet resonator to quiet down things and i'll give you news.

 

Resonators doesn't really help quiet anything down. Just get a Buschur mid-muffler and replace your HFC with it.

 

You don't think vibrant ultra quiet resonator will quiet this thing down ?? it's a very large resonator, even bigger than buschur sd mid muffler and use the same principle: http://vibrantperformance.com/catalo...products_id=46

I would place it as nearest as possible to the HFC

 

lol I misread the type of resonator you planned on running. That one should quiet things down. I was thinking about the usual resonators. Now, you'll have to think about clearance.

 

yes but after the cat I think there is a lot of space, i'll check that tomorrow, on the ground with the canada snow...

 

the air flow output is like a square wave, i think the vibrant muffler will round this wave to a continuous wave, with less DB, at least I hope so...

I'll also shorten the muffler tip and give you update about this tractor pulse problem...

 

The pulse is so loud, i wonder if I put another muffler, it would quiet the deep sound,
but will the pulse be the same loudness at the exit??