exhaust can aka Damping

[Lowe119]

My exhaust can is getting a little too dented up for my taste. Is there any reason I can't just make a carbon "tube" to replace it?

I have never seen the inside of these cans. Are there baffles I have to worry about? Is there anything else in there that makes it work - or is it just a hollow tube?

If there is nothing inside, I don't see why I can't make a carbon replacement and just rivet it onto the existing flanges.....

Any ideas??

[tzracer]

Depends upon the design of the muffler. Most race mufflers consist of an inner perforated tube surrounded by a sound damping material with an outer can. If your muffler is of this design, then yes you should be able to construct a new outer can of the same length and diameter. I would try to purchase commercially available CF tubing and cut to length rather than try to make my own tubing, less likely to crack.

[Lowe119]

How important is that dampening material? Can that be left out for race bikes?

I wonder how strong it has to be? If you crash and your can busts, we can continue with the rest of the weekend without it, right? Or would it be too lean?

I know we talked last year that exhaust is not nessesary to race........... Only problem is if you break the decipal limit at BFR (which RA doesn't have  ;)).

[Super Dave]

I think CCS has db limits.  

Length of the can is part of the tuning of the pipe, you'll need to watch that...

[K3 Chris Onwiler]

I usually use about a foot of 2" steel pipe, threaded on both ends, and a pair of threaded caps.  Drill a small hole in one cap.  Screw on the cap without the hole, then fill the pipe with roofing nails and gunpow....  Oh, wait.  Wrong forum.  Never mind....
 ::)

[Lowe119]

I usually use about a foot of 2" steel pipe, threaded on both ends, and a pair of threaded caps.  Drill a small hole in one cap.  Screw on the cap without the hole, then fill the pipe with roofing nails and gunpow....  Oh, wait.  Wrong forum.  Never mind....
 ::)

Is that .25" wall DOM?

[tzracer]

How important is that dampening material? Can that be left out for race bikes?

That would be damping, not dampening, you garden hose is a dampener. Anything that controls, reduces vibrations or oscillation is damping (like a steering damper or rebound damping).

Any time I have seen it tested, a muffler with no packing made less power than the muffler with packing. That is why you should be repacking your muffler on a regular basis. So yes, in an existing muffler the packing material is important.

[Lowe119]

That would be damping, not dampening, you garden hose is a dampener. Anything that controls, reduces vibrations or oscillation is damping (like a steering damper or rebound damping).

That seems to be a tricky word. I've always called a steering damper a damper, but I thought the material in the exhaust was to dampen (not damp) the noise.

So I looked up the definitions and see that a dampener is to soundproof and a damper is to slow or stop the vibrations of sound or decrease the amplitude of an oscillating system. Pretty fine line, but it's cool to learn something new.  ;D

[racerhall]

i think that back pressure of the exhaust also comes into play as well, that and the length of the pipe will affect hp

[tzracer]

That seems to be a tricky word. I've always called a steering damper a damper, but I thought the material in the exhaust was to dampen (not damp) the noise.

So I looked up the definitions and see that a dampener is to soundproof and a damper is to slow or stop the vibrations of sound or decrease the amplitude of an oscillating system. Pretty fine line, but it's cool to learn something new. Ê;D

Grabbed an acoustics textbook (Fundamentals of Acoustics by Kinsler, Frey, Coppens, Sanders). The word dampening does not appear in the index. A better word for the function of the packing would probably be to call it a sound absorber. Seems the reduction of sound is considered absorption, at least according to this text.

I learned in school that dampening was related to moisture.

[Eric Kelcher]

From Merriam-Webster

Main Entry: damp·en
Pronunciation: 'dam-p&n
Function: verb
Inflected Form(s): damp·ened; damp·en·ing  /'damp-ni[ng], 'dam-p&-/
transitive senses
1 : to check or diminish the activity or vigor of : DEADEN <the heat dampened our spirits>
2 : to make damp <the shower barely dampened the ground>
3 : DAMP 1c
intransitive senses
1 : to become damp
2 : to become deadened or depressed
- damp·en·er  /-n&r/ noun

So dampner is correct for a steering dampner(def. #1),  dampen a shirt (def. #2), the insulation acted as a dampener (def, 3.2)

But on to the revelant part of this.

Contact the manf of the pipe you have they often sell just a sleeve to replace that part and you can order the insulation (dampening  ;) material)to repack.

[Lowe119]

So I could be the Dampener at the wet t-shirt comp?  8)