Silencing the exhaust

turbocad6 said:
ha, & your going to add berk hi flow cats too, I think they'll increase the noise level a bit too, I'm afraid to do hi flow cats at this point, I'm thinking like you, of trying to come up with a way to quiet my exhaust a bit too first at least, I'm thinking about adding a set of supertrapp tips maybe even, which are cool cause you can tune them, not too sure on the look but might not be bad really...
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I'm really stuck on that decision John. I'll see how the sound comes up this Saturday. If it really quiets down, I can maaybbee do HFC. If not, they're for sale. I'm like 70% no to HFCs now..

gto-dave said:
What's the DIA of your midpipe?
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Here's the whole thing:
Kakumei at the arms: 2.5"
Kakumei at the collector: 3"
Reverse Y up to the square flange: 3"
Square flange to the separation: 4" (very short space)
Dual midpipes and dual in rear muffler piping: 2.5"

It's like half of the exhaust is 3" and the other half is 2.5". I believe Stillen headers are 2.5" as well. So the only 2.25" piping left are the stock cats now.
 
generally, you want to stay away from that arrangement, but you knew that already.
The physics seem against you
 
I know that smaller-larger-smaller is not the optimum setup as the middle larger part really acts as a "container" but I didn't have much options really being an AWD. Either don't get the Kakumei and stick with y-pipe and deal with its restrictions or go for the Kakumei and deal with the 3" collector.

The good thing is that no place in the whole setup (except the cats) have instant diameter changes. The 3" region starts with a y-collector and ends with a reverse y-collector so no regions except the tiny 4" flange for the pulses to lose energy. That's probably why I didn't feel any torque loss.

As for the silencer, it is a straight through one and the notches in it are all parallel to the gas flow so it should act more like a flow regulator than a restriction. The diameter reduction makes the pipe closer to 2.5" so that should speed up the gases as well..

That all theory and we all know that theory doesn't mean sht sometimes so we'll see :smile: If even it reduces that boom a bit, I will be happy.
 
I'm not putting it on, I'm putting it inside :smile: That'll slide (and get welded) into the long straight part of this:
View attachment 158847

The long part there is about 4" long, 3" in D. This thing will reduce the inner diameter to about 2.5-2.75" and act like a very unrestricting "muffler". Regular racers (not trackers) use these to work as a "muffler" where the competition requires a muffler. It reduces the sound level around 9 dB supposedly. Even if it reduces it by 5 dB, I'll be happy.

The wholes are there to break sound waves by breaking the air flow close to the surface a bit. It'll look like this from inside:
View attachment 158851
 
It won't be seen Dave. Also, did you ever see the inside of a muffler. Take a look at the one below:
muffler-cutopen.jpg

Compared to regular mufflers, this one is very unrestrictive. Btw, the welded one is a narrow one. Inside is just about 2 inches. Mine will be bigger.
 

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since it's in the 3" section it will really be like a baby muffler, & at a spot that lost velocity before too, this may even help the flow. if you did it in th straight run diameter though, then it would be a restriction, great idea there:biggrin:
 
turbocad6 said:
since it's in the 3" section it will really be like a baby muffler, & at a spot that lost velocity before too, this may even help the flow. if you did it in th straight run diameter though, then it would be a restriction, great idea there:biggrin:
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Exactly my point. I'll try this in the 3" section of the reverse y. If I like the results, I might even put one in the Kakumei collector, given that it won't get in too deep into the Y section and restrict the flow. If this works, it'll be juusstt enough to reduce the annoying low rpm noise while keeping (or by chance, improving) the performance. I just wish some of the chips were parallel to the flow so that I could call it a "regulator muffler" :tongue::rofl:
 
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