LocostUSA.com

I found these images today through another post talking about a removable hard top for a Locost. They used an LS engine with 4" side pipes, cutting ceramic foam into rings, then inserted into the tubes. I kind of like the concept. The ceramic should help to keep the pipes cool, but would this setup still be loud as hell, or would it be decently quiet?

That's kind of cool, but until you run a sound test - with a dB meter - it's just a nice assembly.

I'm no engineer and I don't play one on TV, but it would seem to me that the only function they serve is more of a heat insulator rather than a sound attenuator.

But that would be cool as all get out if it worked!!

Wonder if they'd rattle? I see the crimp that holds them in, but tight enough not to rattle? Especially after heat cycles?

The crimps were only temporary to hold them in place before welding. Two stainless perf cones were built and also welded in from each end of the tube to match what i found in a new set of hushpowers i installed on my sons car. I still haven't started the car so don't know if this has been a complete waste of time but have had a good time designing and fabricating this idea.
You can put your hand on a hot Hushpower without getting hurt and the sound is great but i don't like the shape.

I'm anxious to know how well they work. I really like the look. Where did you get the ceramic? Most every search I try comes back with information about Chinese manufacturers.

This is the link to the St Louis company i got it from. Can't find the invoice.. sorry.
http://www.christyco.com/pdf/crc/Christ ... _Sheet.pdf

I don't know if the site will allow me to attach links but check this out:
http://www.google.com/search?hl=en&safe=off&q=sound+dispersion&bav=on.2,or.r_gc.r_pw.&biw=1252&bih=625&um=1&ie=UTF-8&tbm=isch&source=og&sa=N&tab=wi#um=1&hl=en&safe=off&tbm=isch&sa=1&q=sound+diffuser&pbx=1&oq=sound+diffuser&aq=f&aqi=g4g-m2&aql=&gs_sm=e&gs_upl=5758l9090l0l9917l14l11l0l0l0l0l244l1870l1.8.2l11l0&bav=on.2,or.r_gc.r_pw.&fp=88e7747489c1adf6&biw=1252&bih=625

Alternate the inside diameter of the ceramic disks and you may be onto something.

Seems to me that to attenuate the sound you have to let the exhaust pulses escape thru the perforations. If you surround it with ceramic like that, its like plugging all those holes - you end up with the same result as a straight pipe.

On the other hand, if you used a few of those rings at intervals, you end up with something like a chambered muffler. Might sound pretty good.

Stainless or fiberglass wool is the usual packing material in those types of muffs. Or asbestos! Perforated motorcycle muffs without the packing are louder than the ones with it.

That's my initial response as well.
I wonder though closed cell foam works just fine as sound deadening material so despite the stiffer cell walls could ceramic perform in the same way even if its attenuation is less?
I've never experimented with the various spray on sound deadening materials but one or two of them have a ceramic component iirc.

So how vibration resistant does that foam seem? I'm afraid it will just turn into sand on you. Keep us posted....

This ceramic material is very porous, light weight and seems to have very good sound deadening properties, but I think the end result will be that this stuff will be turned into a powder by the vibration against its self and the steel components of the muffler. The question is how long will it take. I thought about glueing it into the tube with some of the high temp materials used in the manufacture of kiln doors. This will be tried as a solution if the material fails to stay in place.
If you can believe what you read in muffler adds, you can eliminate the harshness/high frequency sound waves in an exhaust tone by forcing the exhaust pulses to escape thru perforations of a certain diameter. Velocity of the exhaust gas thru the holes also plays a role in the resulting tone. The surface area of the perforated material also affects the back pressure ....so cones are usually used to decrease the back pressure.
The perforated cones that were placed tip to tip and welded inside the muffler should kill off a good share of the high freaks with the walls absorbing some also. I have set the sections of the muffler up so I can get back into it for changes or repairs.
Has anyone ever cut open a Hushpower to see what they are using as an insulator/sound deadening material? What ever it is... it is great stuff.

I'd be interested in an update on this. Neat idea, but just want to know the longevity of it. I am pretty sure in the as-shown application, the sound reduction would be very minimal indeed.