t_g_farrell

iTrader: (1)

The kao wool ceramics fiber is good to 2300 F. Its used in building kilns for firing ceramics which easily get to 2300 F for hours on end. It sounds like it was fiber glass.

Also that steel wool may burn, but you'll see when you light it up. Just be prepared with a fire exteinguisher just in case

DriveFast7

iTrader: (1)

I've looked into repacking mufflers and you don't want to wrap the perforated tube super duper tight. If the material is wrapped around the tube too tightly it will greatly increase the density and reflect the sound instead of absorbing it. You want it wrapped on there a little loose.

Also don't need that much tape. Just spiral up and down it once with an inch separating each spiral. The tape will burn in there.

Thanks for the pics, I've wanted to see what that Borla is made of.

dj55b

iTrader: (2)

Cool thanks for the info on wrapping it too tightly, it has actually crossed my mind. so maybe i'll just take off that wire that i actually put on put ill keep it on the end so it doesn't move around from side to side kinda deal like i think happened in the borla. As for the tape i know it will be burning up and will probably stink for a while.

As far as the wool bruning up i don't see it happening. The stuff that i used on the first layer the coarse stuff which will be taking the most abuse is the on the first later and isnt' much thinner than the stuff in the borla. So i can see it lasting but time could prove me wrong.

If i need to improvise on anything else please let me know.

orion84gsl

iTrader: (5)

Thats awfully nice of Borla to reimburse you even though you didnt buy it from them. Don't you owe me a few bucks for gas money for taking you to Wal-mart to get the steel wool?:P

Jeezus

iTrader: (4)

Thats awesome to hear. Just further pushes me towards being a Borla fanboy!

On a side note, my borla's have held numerous backfires and flames and still sound great to this day!

http://ca.youtube.com/watch?v=QchXiwd1toU

Jaime Enriquez

This thread on the AusRotary forum had great info on muff building...
http://ausrotary.com/viewtopic.php?f=16&t=115214

OneRotor

iTrader: (3)

haha, muff building...

impressive work popping the muffler.

dj55b

iTrader: (2)

Well finally got everything done today. I was able to tig weld the whole thing up and should have in it in the car in a few moment. Here's a couple of shots of it. I'll let you know how it sounds later on

Also i know i'm not the greatest tig welder but i gave it my best. I thought it wasn't bad for this being the second time I do pipe welding.

For the tube that i used actually the sidewall was more like .120 or something like that i believe. I couldn't get it in 1/16".

Kerebrus

iTrader: (30)

very nicely done

dj55b

iTrader: (2)

Well took it out for a test run all after noon. I'm amazed on how much it has cut down on noise! Inside the car it has cut down about 1/3 of what he borla was out putting noise wise, and on the inside under 3k rpm or so I would say it has muffled it by about 1/2. Highway cruising is definatly alot nicer now. The sound is also alot deeper now. I had my EGT's reach about 1700*F roughly without damaging it. Also to my surprise on the first start up, it didn't smoke up that paper tape like i thought it would. Not a hint of smoke came out. I'm really temped to take out that Magnaflow in the back and do something similar to it. I think from now on I'll just be building my own mufflers. Well i'll see how long things last first.

t_g_farrell

iTrader: (1)

At first when I saw you doing this I was like "Why?" but now that your reporting a better experience with the handmade muffler I changed my mind. I have a project I'm looking at where I may need a lot of extra muffling in a much shorter muffler and you've given me some great ideas on how I can achieve it or what I want to look for.

Good work. Keep the thread up to date with observations.

dj55b

iTrader: (2)

Now just to keep things in mind the center pipe is not a straight pipe, because i had an offset muffler (according to my calculations 7 degree bends at both ends.) This is i think one of the key things to actually achieve a quieter mufflers because the waves can be pushed into the packing better. Also not sure is you saw on the muffler or not, but where it actually bends, the outer pipe is actually offset from the center pipe so that the area behind the bends on each end have more air room to absorb the sound.

If anyone has anymore question please let me know. And trust me I surprised myself when I first started up the car and heard how quiet it is. I actually didn't have much hope into it neither but it was cheap enough to do and try and i knew people have done it in the past. Besides if you're packing it with pretty much what any company out there uses, whats the difference besides you knowing what is inside the muffler.

PercentSevenC

Wow, that's cool that it turned out so well. Any chance of getting some video/sound clips of it?

t_g_farrell

iTrader: (1)

Check out this article on muffler design. Looks like your headed in the right direction.

http://researchnews.osu.edu/archive/fibrmufl.htm

t_g_farrell

iTrader: (1)

And s a great resource on how the various mufflers are structured internally:

http://furinox.com/jappweb/index.php...id=4&Itemid=28

dj55b

iTrader: (2)

I'll try to get some video maybe later on tonight after I get off work. I had Martin (Immanuel) from the forum go with a spin with me and he said pretty much the same thing, Chris (Orion84gsl) might be going with a sping with my today in the car to let me know what he things of it. The guys at school definatly noticed the deeper/throatier sound of it.

bad 83

iTrader: (3)

This has been very educational. I have been racking my brains trying to figure out a good free flowing exhaust that's not loud as hell for my bridgeport. This has given me alot to think about.

DriveFast7

iTrader: (1)

Glad it worked out. Did you keep the center pipe packed so tightly or did you re-wrap it.

orion84gsl

iTrader: (5)

Nicely done Sam, your welds look OK to me. I won't be going for a spin with you, at least not til next weekend. I'm off to Winnipeg in the morning so I'll give ya a shout when I get back.

dj55b

iTrader: (2)

I did keep it the way i had it. When i wrapped the wool on the pipe, with that paper tape it doesn't take too much to actually rip it so it doesn't really tighten it as much as you think or look like. Like i said though I did remove the wire that I had swirled around it though to let it expand better when it burned up the tape. Also another thing that give me a little more cushion space too is that Furnace insulation stuff. My buddy was telling me that it does shrink a bit once it get hot. So everything should still be fairly snug but not rediculisly tight. One thing that might be interesting to expert with is to see how much more noise is taken out by using something that maybe had a sharper angle something like an offset - offset muffler that should have almost double the angle of this pipe.

Like i said i'm really tempted to redo the magnaflow in the back, but for that I might get a little more creative. We'll see if I ever get to it. Or maybe I'll just buy one that is junk off the net (maybe another borla ) and use that as my test piece. I need to redo all my exhaust piping anyways to mandrel bent piping and properly welded and fitted.

Jeff20B

iTrader: (13)

This is the coolest mod I've seen in a long time. I have a dead RB presilencer (it's 20 years old and suffered internal water damage). I'm considering cutting the shell off and packing with new steel wool.

dj55b

iTrader: (2)

Thanks for the compliments ... I still have to get videos but haven't had a chance to do it though. I might be able to do it later on today or tomorrow sometime. I feel like going on ebay buying every single busted borla and rebuilding it my way then selling them for rotary use One of my other buddies heard it today and said it sounded like a muscle car now with the deeper tone So definatly getting compliments on it.

Here's a good candidate if someone has a 2" piping muffler:

http://cgi.ebay.com/ebaymotors/Borla...spagenameZWDVW

dj55b

iTrader: (2)

Well I've finally had a chance to get a few sound clips of my exhaust. The first one is with my new homemade muffler and the magnaflow in the back. The second one is of just my magnaflow. I don't think I have a video of my borla and magnalow except for when i was doing the dyno runs and you can find those on youtube anyways. The last one is with the camera sitting on the passenger side floor and taking sound from the inside. Remember thats as close to the inside noise as I can get and you should be able to tell that its fairly quiet. The same camera was used for both mufflers too so its a good sound comparison you can really tell the difference in low rpms. I should mention that the inside the car one was sitting inside a car paking lot so you're hearing a bit of echo with my windows down.

http://www.youtube.com/watch?v=Wpc8aLu23Mo

http://www.youtube.com/watch?v=ROdbcjjA_Cc

http://www.youtube.com/watch?v=3t4R_id9wgA

dj55b

iTrader: (2)

A bit of an update on this, I was out on the track with it all day today, and DD it and still no issues. Seems like it might hold up well!

Jeff20B

iTrader: (13)

That's good to know. My MG midget needs a presilencer and I have that dead RB just sitting there. I'll drop the OD down to 3" since there is limited room under the car. Think that will work if I got a length of 3" SS pipe in .063 or 16" wall thickness? How thick is your SS shell pipe?