Hello GRM Hive of knowledge,
I am interested in the burns stainless 2 stage quiet muffler..
https://burnsstainless.com/products/2-stage-mufflers?variant=8143763177563
Quite Pricey as I am sure the quality is superb.. are they truly quiet? After having some Flowmaster and Magnaflow 2 chambers that are loud and Drone a lot on the highway I am done with that style. I like the compact form factor, quality materials, and flow rate of the burns, I just would like quiet to go with the price tag.
Thanks, Greg
Magnaflow makes chamber style mufflers? I thought all they did were nice perf-core absorption mufflers.
Flowmaster are really loud and restrictive, but they have a cool name...
I wonder what is "two stage" about those particular mufflers. The old made-in-Italy presilencers from Racing Beat could be considered "two stage", basically a 24" tube, with the first 6" or so just open, and then about 18" of perf-core muffler. Kind of like one segment of a firearms silencer. They worked REALLY well at making rotaries quiet.
Either way, exhaust noise and muffler internal volume are directly linked. You need a large space to kill exhaust noise, small mufflers never work well.
This is secondhand info (no personal experience), but I have heard concerns about longevity with the Burns Stainless stuff. It's light because it's thin gauge, and at least in some cases it seems to have been too thin for extended use. "race parts".
In reply to codrus (Forum Supporter) :
Thanks - that sounds like it's right. - I have had stuff like that happen even on garden vareiry parts store aluminized stuff if it's stressed too much.
I can always weld it back up or put extra hangers in the exhaust system is needed, but I would rather not if possible.
Greg
Shaun
Dork
4/13/21 12:21 p.m.
There was a racing oriented muffler test somewhere on the interwebs (maybe here?) I read once and a Burns product won by a mile in sound reduction and allowed the most power by a bit at the same time.
Shaun said:
There was a racing oriented muffler test somewhere on the interwebs (maybe here?) I read once and a Burns product won by a mile in sound reduction and allowed the most power by a bit at the same time.
Thanks, It would be awesome to see the data on that one.
Greg
Having run a Burn's Stainless single stage for a couple years the two stage version intrigues me. I'm curious what the internal construction looks like. I'm with Pete in that I don't know what makes them "two stage." The SM-300-625-17-2S version looks just like the SM-300-625-17 I have but with another piece making up the main body. Same overall size and everything. Mine's just an interior perforated tube surrounded by ~1" of SS "scrubble" that's then surrounded by ~1/2" of fiberglass mat. Externally, there's no sign of degredation after more than 2 years on my RX7. Internally, I have no idea. I couldn't tell you if the car's gotten louder over time or not. Something, something, rotary exhaust volume and hearing loss...
$600 is pretty steep, has anyone got a more grassroots solution?
In reply to Carbon (Forum Supporter) :
Depends on your goals.
If that thing works as advertised, it'd be half the expense of a Racing Beat system, that is now painfully loud with their new supplier...
I like that it is rebuildable without use of an angle grinder to open the muffler and most of a spool of MIG wire to close it up again. So you can repack it every year instead of replace it every year.
Replaced the Burns Stainless race muffler (SM-250-350-17 with scrubble) with the 2-stage quiet muffler (SM-250-450-17-2S) in a custom FR-S center exit catback I designed using all Burns Stainless tubing (16gauge with muffler where stock resonator was under the car in transmission tunnel...) much improved and deeper sound... but still loud. Not annoyingly loud like the race muffler though (HAD to wear ear protection with that one).
Muffler location in the custom center exit catback...
Two-stage muffler is diverting type, not straight through like the race muffler - wish I had took a picture of the inlet side, but basically have a v-wedge that diverts flow outwards... not sure what is after it in the second section of the body. Absolutely prefer the two-stage over the race muffler... no contest or second thoughts... just a matter of the price jumping up 2-fold...
Unfortunately I don't have any kind of direct comparison videos, but this is what I do have...
With the race muffler:
With the 2 stage quiet muffler:
In reply to Vracer111 :
Big difference with the 2 stage. Since it's no longer a straight-through design have you noticed any changes in power?
I actually sold my FR-S about 10 months ago soon after installing the 2 stage quiet muffler. From short time I had the 2-stage muffler there was no really noticeable changes in power delivery I can recall. Was seriously thinking of doing another custom Burns Stainless catback exhaust with 2-stage muffler for my Nissan Frontier, but there was a new NISMO exhaust which recently came out that I went with a few months back instead (much cheaper [just a bit more than the Burns muffler alone would cost] and fully 304 stainless and TIG welded as well.)
Thanks for the videos.
As noted, The Caparisons are a bit difficult as the video is in a different position for the 2 stage vs one stage.
It's kind of difficult to tell if there is even a muffler on for the one stage video. It-s Loud!
Greg
Burns mufflers are nice, but they are definitely for that last stretch of losing weight, I cannot justify their cost in most instances, plus they usually need to be repacked after a season or 2 because they are loosely packed (to keep weight down). I feel the baffle in the 2stage might be too turbulent in some maxed out systems, and probably best used at the very end of an exhaust for max effectiveness (baffle difuses the exiting sound waves right as they are about to be expelled into the atmosphere).
Look into the Vibrant 'Ultra Quiet' muffler/resonator. Absolute excellent unit that actually significantly dampens sound well per its diminutive size. I use this often as the lone muffler in a system and also as a 2ndary muffler for very tame results.
Another small yet effective solution is the Flowmaster HP2 laminar mufflers, I have no idea the quality of them since the change to China production however.
Consider Coast Fabrication for another source of extreme lightweight race mufflers
In reply to malibuguy :
I definitely need to repack the single stage on my RX7 based off my track day last week. I've seen pictures online but it'll be interesting to see just what's in there myself. I have one of the "large body" 6.25" diameter mufflers that's advertised as having both "scrubble" and fiberglass packing. I know when I purchased it I specified scrubble online (because rotary) but I'm now wondering what I really got. I've got a repacking kit ready when I have the time. I'm also going to put another single stage, a small body 4.5" muffler, just upstream. Since they are repackable it does open up a lot of options. No requirement to use Burn's stuff. There's some serious stuff used in industrial heat exchangers like ceramic mat that is supposedly more durable. Heavier too, no doubt.
In reply to malibuguy :
Thanks for the other options!
Greg
malibuguy said:
Look into the Vibrant 'Ultra Quiet' muffler/resonator. Absolute excellent unit that actually significantly dampens sound well per its diminutive size. I use this often as the lone muffler in a system and also as a 2ndary muffler for very tame results.
Another vote for Vibrant Performance's products. Used them on my R32 and was quite pleased. Construction quality was good and it seems to be doing the job.
The larger Flowmasters actually flow quite well, and reduce sound significantly without droning.
The bonus is that they sound great.
The problem with them is that they're not particularly well built and tend to fall apart much sooner than they should. I don't know if the SS option makes that any better.
In reply to infernosg :
Ive had good sucess with ceramic mat...however I do not live with doritos so I cannot speak with experience. Ive only done 2 or 3 rotary exhausts in the last 15 years.
Ceramic mat in the Borla muffler I repacked
In reply to malibuguy :
That looks like the stuff I used to repack a Racing Beat muffler. IIRC I calculated its internal volume at 1080ci and I used 2000ci worth of packing material.
When I cut the muffler open, the original packing was completely gone except for half a Brillo pad's size chunk of fiberglass. So much for being filled with stainless steel swarf.
Pete. (l33t FS) said:
In reply to malibuguy :
That looks like the stuff I used to repack a Racing Beat muffler. IIRC I calculated its internal volume at 1080ci and I used 2000ci worth of packing material.
When I cut the muffler open, the original packing was completely gone except for half a Brillo pad's size chunk of fiberglass. So much for being filled with stainless steel swarf.
I made a YouTube video on repacking that one. The old packing came out in 3 main chunks.
Ive repacked Magnaflows that had nearly nothing left.
I don’t know why but ceramic fibre does a much better job at attenuating sound than does fibreglass.
I have a lifetime supply of it from when I used to service heat treat furnaces and use it on my bikes.
In reply to Pete. (l33t FS) :
LOL, that's honestly about what I'm expecting to come out of my current muffler. Burn's gives recommendations for how much scrubble and/or fiber to use but I think I'm going to try to stuff more in there. Lightweight is good but I'm not chasing every lb just yet.
Looks like ceramic mat is the way to go once this next round of packing is dead. I've seen some other crazy SS/ceramic matrix stuff that's pleated and can be wrapped around the perforated core to act as a heat shield for the rest of the packing. That combined with the ceramic mat could be the magic combination for quieting the spinning triangles.
In reply to Mr. Peabody :
I've found that the bike world, especially the two stroke variety, has a wealth of info on exhaust packing that doesn't seem to be too well translated to our four-wheeled side of motorsports.
