For the sake of more argument, could a guy quiet down a pipe like this? It has a baffle with fiberglass wrapping already -- but the center of the pipe is wide open. Could a more restrictive baffle be fashioned to fit in the current pipe? Anyone done this?
That's a good question... OKAY, agruments aside, does anyone have an answer to this question. It would be very interesting to learn if it is possible. My initial thought would be that it would cause too much back presure... but maybe not.
Anyone?
Not SOHC4, but an applicable experience.
I was given a CX500 with a fairly new MAC 2 into 1 installed on it. When I eventually got it running, I found out that the, pipe was REALLY loud. Not wanting to risk further bouts with tinitus, I set about quieting the beast (while wearing earplugs).
Deconstruction:
The "baffle" was simply a perforated tube with some holes in it to allow some noise to enter the outer megaphone chamber and reverberate in there. You could see the full diameter of the perforated tube the entire length of the "muffler". Okaaaay..... low restriction.
I packed the outer chamber with steel wool. This helped damp and soften the noise a bit. And, the engine ran better with the added restriction since the carbs had not been rejetted from stock configuration. But, the exhaust shock waves and heat eventually resulted in blowing bits of glowing steel embers out the back. After making and destroying a list of people to drive ahead of... I did some online research of muffler designs.
Striking a balance between sound and restriction is not easy. Steel wool and fiberglass muffle sound by creating turbulence that distorts the sound wave pulses from the engine ports. The more turbulence, the more sound damping as the waves distort into each other and cancel themselves out. However, turbulence is restrictive to exhaust flow. I learned that the less restrictive exhaust designs have no packing of fiberous materials because of the flow restricting turbulance created. Instead they use strategic placement of angled baffles to redirect exhaust flow with minimal restriction, yet reflect sound pulses in the reverse direction so they may cancel. A balance is struck between multiple baffle stages and the desired restriction of air flow.
After learning this, I re-examined the Mac muffler design with an eye toward baffle insertion and placement. Let's see, trial and error method, or do the math for exhaust impulse timing/distance traveled over multiple RPMs to determine baffle placement and spacing.
Then I found a nearly new stock exhaust system, designed and implemented by Honda complete with balance box and strategic baffling, on eBay for what I now considered a reasonable price (given my recent illumination). I installed that and am happy to report no re-occurance of tinitus.
And guess what! The stock carb jetting (aleady installed) works perfectly with the stock exhaust! So, the engine runs MUCH better over teh entire range, too!
The only drawback, is that I now have to find someone to buy a really loud CX500 exhaust system in really good condition, hopefully far away from where I live in California (sound travels, you know).
Cheers,
And, Good luck!
