I realize this may be a crazy question but has anyone used carbon fiber as a silencer packing? It’s sound insulation properties are very high and it won’t burn or get brittle. I know it’s expensive but it might just last indefinitely in a muffler and could possibly be reused once it’s fouled. Seems to me that sound decibels would decrease and would last a good long time. When it comes to acoustic properties, carbon fiber is often compared to materials like aluminum, steel, and fiberglass. Carbon fiber generally has better acoustic performance than these materials, as it has a higher stiffness to weight ratio and lower density.
 

Laugh if you will but I’m just wondering. Cheers!

Oh, forgot to mention that I did a quick back of the napkin estimate and by volume 1 square meter/yard would be equal 1,200 grams of fiberglass packing so you could repack a typical trials silencer with one square yard three times. Typical costs range from $30ish to $45ish dollars per sq. yd. That would only cost $10ish to $15ish per repack.
 

Maybe I’ve gone bats! Probably.

 

The concept sounds good, I have to wonder how long it would last, how it would sound, if it would capture oil more, and such.  If you ever end up giving it a try I would be interested in the outcome. 

I’ll wait to see what others think before trying but I agree with your concerns. It’d be interesting to see and hear.

Makes sense, I admit I am quite interested in hearing what others think as well.  Though if I still had a 2T bike I would be willing to give it a try.  Only have a couple of Montesa 4T's at this time so not really in the cards for me. 

I’ll let you know if I pull the trigger.

Theres no such thing as indefinitely in a 2 stroke. Where do you mean? The centre box or the tail pipe? Oil contamination forshortens the life of silencer packing before anything else. Scorpa said their sy silencer had ceramic packing that never needed changing. Bikes started to sound rough and performance dropped after about a year. It may have a better chance in a 4 stroke. Otherwise i like your thinking. The non woven stuff i would imagine being the best. Also, many people think silencer packing is only to silence the bike. Engine performance is extrememly dependent on packing type and density. Glass fibre isnt heavy, so theres neglibgle weight savings. If the time to clog the cf is the same as the gf, i dont see where the benefit comes from. But im also tempted to try lol

Edited March 12, 20242 yr by faussy

Thanks for the input. I meant only in the tail end of the pipe. The oil contamination was what I thought might kill the idea too but I think it still might be worth a try. Carbon fiber weighs about 15% less than fiberglass so the weight savings is negligible but I think density would be about the same keeping performance the same. Longevity and resiliency to heat and oil are the goals in my head. It can definitely take the heat better than fiberglass so that leaves the dreaded oil problem. If you try it using the unidirectional fiber let me know and I’ll try woven. I don’t think this idea will save the world but it seems like a good experiment to me. Thanks again for jumping in!

I seem to remember that when carbon fibre is involved in fire it releases micro hooked fragments that just love to lodge in lungs. Potentially quite a serious problem for Firefighters due to modern car design and other forms of construction. 

Not that in a silencer it would be directly involved in a fire, but it's close enough to be degraded and shot out the tailpipe with the heat that is produced. 

Just a thought !

Edited March 16, 20242 yr by rotors7

Wow! Did not know that. Thanks for jumping in. This is the very reason I posted the question here to learn what I don’t know. Given what you said I don’t think I’ll try my experiment. Thank you!

No worries, I can remember at the time, being quite concerned about it and wanting to make sure all us Firemen wore breathing apparatus at any possible fire involving carbon fibre. 

It's great stuff but not when it burns, a bit like that once wonderful material called asbestos! 

I am glad to learn this as well, thank you!