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SuzukiSavage.com
/cgi-bin/YaBB.pl General Category >> Rubber Side Down! >> Muffler Shootout /cgi-bin/YaBB.pl?num=1605160449 Message started by DragBikeMike on 11/11/20 at 21:54:09 |
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Title: Muffler Shootout Post by DragBikeMike on 11/11/20 at 21:54:09 Back in September, I did a report on the 97mm engine I built. The engine ran well but it had a nagging oil leak. I patched up the leak just to allow me to finish testing. At the conclusion of the test, I decided to throw a Mac exhaust system on just to see if it made any difference. To my amazement, that exhaust system made a measurable difference in performance. The Mac system lobbed about 0.23 seconds off my 3rd gear 4K to 7K time. Unfortunately, it was way too loud. I just couldn’t leave horsepower on the table. I had to find a way to reduce the exhaust restriction without raising the noise to rock concert proportions. I had been running a Mac 1.79” ID header pipe for a long time. With that Mac header and a modified stock muffler, my 94mm engine made 41 HP (11/19/20 The tight quench engine with 10.4:1 CR, not the pop-top engine with 9.2:1 CR. I've never dynoed the pop-top engine.). I thought the exhaust system was good. It made lots of power and it was quiet. But the switch to the full Mac system on the 97mm engine proved that the modified stock muffler wasn’t cutting it. With the 97mm engine on the workbench for repairs, and the 94mm engine in the bike for learning projects, it was time for some muffler testing. |
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Title: Re: Muffler Shootout Post by DragBikeMike on 11/11/20 at 21:54:41 I tested I evaluated the mufflers based on flow restriction, weight, noise level, sound quality, acceleration, and aesthetics. |
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Title: Re: Muffler Shootout Post by DragBikeMike on 11/11/20 at 21:56:15 All of the mufflers were installed on a Mac 1.79” ID header pipe. I realize that a 1.62” ID header would be a better choice, but the Mac header is off-the-shelf. So, no messing around with muffler shops trying to get a custom header bent, flange welded on, fitup issues, back & forth, extreme heat coatings, etc., etc. The Mac header provides an ample cross section to support significantly more exhaust flow than the stock 1.30” ID header. The Mac header also lends itself to installation of almost any aftermarket motorcycle muffler. That’s because the pipe runs parallel to the fore/aft centerline of the frame. See how the Mac pipe runs parallel to the stock muffler bracket. Changing to a different muffler is a simple bolt on proposition. |
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Title: Re: Muffler Shootout Post by DragBikeMike on 11/11/20 at 21:56:54 The stock header pipe requires a special adapter. See how the stock pipe angles in toward the rear wheel. You need an adapter with a kink in it to install an aftermarket muffler. |
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Title: Re: Muffler Shootout Post by DragBikeMike on 11/11/20 at 21:57:40 I used my poor man’s flow bench as a test stand to measure flow resistance. I simply pulled on each muffler with two full-size shop vacs (that’s about 10 HP worth of vacuum potential) and measured the depression with a simple U-Tube manometer. This picture shows a muffler getting the chrome sucked off. |
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Title: Re: Muffler Shootout Post by DragBikeMike on 11/11/20 at 21:58:31 To establish a benchmark for performance, I ran several timed acceleration runs with the modified stock muffler to see where things stood. The 3rd gear time from 4000 rpm to 7000 rpm was 8.20 seconds. That’s about 0.48 seconds slower than it was several months ago. Why was it slower? After pondering that for a while, I realized that I have a new rear tire that weighs significantly more and is a full half-inch larger diameter. Also, the ignition timing is advanced 2 degrees from where it was when it ran faster. To be sure that I had a solid benchmark, I ran several more 3rd gear pulls. It hung in there right around 8.20 seconds. So, the benchmark for acceleration was 8.20 seconds. |
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Title: Re: Muffler Shootout Post by DragBikeMike on 11/11/20 at 21:59:23 The Here you see the modified stock LS650 muffler hangin off a Mac 1.79” ID header pipe. This setup has served me well. It makes good power and is quiet. |
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Title: Re: Muffler Shootout Post by DragBikeMike on 11/11/20 at 22:00:03 The modified stock muffler uses this larger transit tube to shuttle hot gas from the front chamber to the rear chamber. The stock internal tube is only about ½” diameter. The additional exterior transit tube is ¾”. |
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Title: Re: Muffler Shootout Post by DragBikeMike on 11/11/20 at 22:00:39 At 1” ID, the exit tube is also significantly larger. It transfers the hot gas from the center chamber in the muffler to the atmosphere. These mods got the stock muffler flowing almost as good as the Dyna. Close but no cigar. |
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Title: Re: Muffler Shootout Post by DragBikeMike on 11/11/20 at 22:02:34 Installed on the motorcycle, the modified stock muffler looks sorta stock. I like the look, but then my taste in mufflers may not be your cup of tea. |
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Title: Re: Muffler Shootout Post by DragBikeMike on 11/11/20 at 22:03:21 The Harley muffler is typical Big Twin hardware. They usually get replaced about one-week after the customer picks up their new motorcycle. This one has a catalyst. Excellent quality and it looks good. |
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Title: Re: Muffler Shootout Post by DragBikeMike on 11/11/20 at 22:03:57 The Harley baffle tube is 1.25” ID and the perforations are about .16” diameter. There are 36 perforations on the exit side. I have no idea how many perforations are on the inlet side because the catalyst blocks the view. |
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Title: Re: Muffler Shootout Post by DragBikeMike on 11/11/20 at 22:04:37 This is the catalyst on the inlet side of the Dyna muffler. If you have a Harley muffler and you see something like this in the inlet, expect it to run major hot (possibly glowing red). Our carbureted engine simply runs too rich, which causes the catalyst to overheat. It seems to be a common issue. |
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Title: Re: Muffler Shootout Post by DragBikeMike on 11/11/20 at 22:05:13 With the Mac header pipe, installing the Harley muffler on the LS650 is a snap. All you need is a simple, off-the-shelf, 2” x 1.75” adapter and two clamps. |
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Title: Re: Muffler Shootout Post by DragBikeMike on 11/11/20 at 22:05:53 Installed on the motorcycle the Dyna looks just right. It has the classic cruiser look. With a standard exhaust adapter, it fits up to the Mac header perfectly and aligns with the exhaust mount so that one bolt can be used to attach the muffler to the mount. No welding, no bending, just bolt it on. |
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Title: Re: Muffler Shootout Post by DragBikeMike on 11/11/20 at 22:06:38 The Mac muffler is a reverse cone. It’s a handsome devil. |
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Title: Re: Muffler Shootout Post by DragBikeMike on 11/11/20 at 22:07:19 Although the Mac has a core that could be called a baffle, it really is straight through. The tube ID is 1.42” but the louvers tend to reduce the ID to around 1.02”. The hot gas can easily cascade around and over the louvers, so I suspect the cross section is equivalent to something quite a bit larger than 1.02” diameter. The test data supports that assumption. The Black Mac has a core ID closer to 1.42”. |
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Title: Re: Muffler Shootout Post by DragBikeMike on 11/11/20 at 22:07:52 As you can see, the Mac is straight thru. |
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Title: Re: Muffler Shootout Post by DragBikeMike on 11/11/20 at 22:08:29 Because the Mac muffler comes with the Mac header, it is a bolt on affair unless you manage to get one of the bargain-basement kits that Dennis Kirk was unloading. Even then, the fix is pretty easy. It’s a very nice-looking system. Info on the Black Mac was posted at the end of this thread on 11/22/20. |
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Title: Re: Muffler Shootout Post by DragBikeMike on 11/11/20 at 22:09:53 The Cherry Bomb is (what can I say?) a typical Cherry Bomb. Somewhat crude. It sports an ample 1.75” diameter hole straight through the center. It’s a featherweight too. I’ve had this one for several years. As I recall, I bought it at O”Reilly for about $25. It’s a Thrush part number 24210. BTW, you can also get one of these in stainless steel. |
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Title: Re: Muffler Shootout Post by DragBikeMike on 11/11/20 at 22:10:32 I bet this one isn’t gonna be too restrictive. I also bet it isn’t gonna be too quiet. |
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Title: Re: Muffler Shootout Post by DragBikeMike on 11/11/20 at 22:11:06 Anticipating that the C-Bomb was gonna wake the dead, I fabricated a baffle tube to snuff out the noise. The largest practical tube ID is about 1”. A larger baffle tube will reduce the exterior cross section (area between the baffle OD and the glass-pack ID) to a section smaller than the tube ID. Sometimes you reach the point of diminishing returns. |
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Title: Re: Muffler Shootout Post by DragBikeMike on 11/11/20 at 22:11:42 With a proper baffle tube, you can no longer use the C-Bomb as a spy glass. It’s not straight thru anymore. |
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Title: Re: Muffler Shootout Post by DragBikeMike on 11/11/20 at 22:12:27 Installation requires a 2” x 1.875” adapter. I was able to find one at O”Reilly auto parts. Since this was a test, I didn’t get too carried away with the mount. Just a chunk of aluminum and a couple of stainless-steel clamps. It worked fine and was easy to do. If I decide to permanently install the C-Bomb, I will come up with something a little more robust. Again, with the Mac header, installation is a snap. |
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Title: Re: Muffler Shootout Post by DragBikeMike on 11/11/20 at 22:13:04 The C-Bomb has a look all its own. I think it would look good on a bobber. Of course, an industrious fellow would strip off that red powder coat and give the thing a nice layer of flat-black high-temp paint. Then it would look reasonable & proper. |
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Title: Re: Muffler Shootout Post by DragBikeMike on 11/11/20 at 22:13:54 The LCGP resonator is polished stainless steel. Looks to be good quality. The welds are nice, the finish is too. It has a mighty big 2.5” hole straight through the center. I had to install a baffle in this one before I even tried to ride the bike. I also didn’t bother to test it for restriction without the baffle because the hole through the center is so big that it wouldn’t have pulled any vacuum on my test rig. I bought it on Amazon for $36 delivered. LCGP part number 254019. Website is www.lcgppro.com. |
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Title: Re: Muffler Shootout Post by DragBikeMike on 11/11/20 at 22:14:31 Without a baffle, the LCGP is a one-way ticket to anti-socialville. C-Bomb on left, LCGP on right. |
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Title: Re: Muffler Shootout Post by DragBikeMike on 11/11/20 at 22:15:12 The baffle is just a piece of 1.5” conduit. It has a plug in the center with 84 holes on the inlet side of the plug and 84 holes on the outlet side. The holes are .17”. There is a fitting on each end to seal it to the glass-pack core. The plug in the center forces the flow to run out of the perforations into the area between the tube OD and the glass-pack ID, then back through the perforations into the tube ID and out the exit. Acoustic energy is attenuated by restriction, direction change, and absorption. 12/16/20 I also built a LCGP with a 1.75" baffle tube. Construction is essentially the same with the exception that the baffle tube is larger. It flowed much better and was significantly faster. I updated this post to include data on the 1.75" baffle. |
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Title: Re: Muffler Shootout Post by DragBikeMike on 11/11/20 at 22:15:50 A standard 2” x 2.5” reducer is all that is needed to marry it up to the Mac header pipe. |
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Title: Re: Muffler Shootout Post by DragBikeMike on 11/11/20 at 22:16:33 I had an extra Mac muffler bracket that I modified to mount the LCGP muffler. A couple of 5” stainless steel clamps and I was in business. |
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Title: Re: Muffler Shootout Post by DragBikeMike on 11/11/20 at 22:17:13 The LCGP looks nice. It’s kinda like an old school Britt bike muffler. It was easy to install. |
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Title: Re: Muffler Shootout Post by DragBikeMike on 11/11/20 at 22:18:53 I tested each muffler for flow restriction. The manometer reading is directly proportional to restriction, higher inches H2O equals more restriction. Here’s how they stacked up. Modified stock: 42-1/2” H2O Dyna: 41” H2O Cherry Bomb with baffle: 41” H2O LCGP with 1.5" baffle: 33-1/2” H2O Mac (chrome): 32-1/2” H2O LCGP with 1.75" baffle: 31-1/2" H2O Mac (black): 26" H2O Cherry Bomb: 16-3/4” H2O It’s pretty obvious that the Cherry Bomb is the least restrictive. Of course, the LCGP would be even less restrictive without the baffle, but it would be exactly like running a straight pipe. Simply out of the question. |
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Title: Re: Muffler Shootout Post by DragBikeMike on 11/11/20 at 22:20:04 The weights are as follows: Stock: 14 lbs Dyna: 7 lbs LCGP with baffle: 6 lbs Mac: 5 lbs C-Bomb with baffle: 4 lbs C-Bomb: 3 lbs Why am I not surprised that the stock muffler is a porker? |
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Title: Re: Muffler Shootout Post by DragBikeMike on 11/11/20 at 22:21:49 Noise levels: Modified stock muffler: very quiet Dyna: very quiet C-Bomb with baffle: very quiet LCGP with baffle (1.5" & 1.75"): very quiet Mac (chrome): painfully loud Mac (black): crushingly loud Mac ((black) packed: loud but tolerable C-Bomb: crushingly loud |
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Title: Re: Muffler Shootout Post by DragBikeMike on 11/11/20 at 22:24:33 Sound quality: Modified stock: It sounds almost exactly like the stock muffler. It’s a little lower frequency so it’s slightly less irritating. Sounds a lot like a small industrial engine, like a pressure washer or a farm implement. Not pleasant, not powerful, just sort of utilitarian. Dyna: It sounds much better than the stock muffler. It obviously has some sort of wool packing in there because the grating high-frequency noise is filtered out. It’s a nice sounding muffler with a nice tone. Not like a V-Twin but much better than stock. Note that in the past I have made negative comments about the Dyna, stating that it was too noisy. I don’t know how I arrived at that conclusion. Maybe I slipped it onto the stock header for a quick & dirty listen, possibly didn’t have a good seal between muffler & header. For this test it was installed correctly, and the sound was good. Mac (chrome): In a word, obnoxious. Emits an extremely loud, high-frequency snap, crackle, pop. The absence of any wool packing is evident because every decibel of acoustic energy seems to escape this things grip. While I am sure an open pipe would be louder, this thing will flat make you some enemies. If you think other bikers will admire the manly music wafting from your exhaust tip, think again. It’s all high-frequency cacophony and sounds anemic. I hate it. Mac (black): Similar to the C-Bomb. Very powerful low-frequency sound but the volume is bone-crushing. It is so loud I literally had to sneak out of my neighborhood and could not run the thing in the garage for any sort of tuning. It is a good deep rumble and sports the sort of sound quality that most bikers are looking for, but the volume is simply too much. Waaaaaaaay too much. Please, don’t run this muffler without packing. With ceramic wool packing it’s tolerable until you screw on the throttle. Added 11/22/20. C-Bomb: Very powerful low-frequency sound but the volume is bone-crushing. It is so loud I literally had to sneak out of my neighborhood and could not run the thing in the garage for any sort of tuning. It is a good deep rumble and sports the sort of sound quality that most bikers are looking for, but the volume is simply too much. Waaaaaaaay too much. Please, don’t run this muffler without a baffle. C-Bomb with Baffle: Top notch sound quality. Very nice low-frequency thud, thud, thud. Deep, throaty, very pleasing, powerful note. The combination of restriction, directional change, and absorption really does the trick. Great sounding muffler. LCGP with Baffle: Didn’t even attempt to run this one without a baffle. Same comments as the C-Bomb with baffle. Very nice sounding muffler. Both the 1.5" baffle and 1.75" baffle were very quiet and had a nice healthy sound, but the 1.75" baffle produced an even lower frequncy note. Even more pleasing than the 1.5" baffle. Both these setups are excellent. |
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Title: Re: Muffler Shootout Post by DragBikeMike on 11/11/20 at 22:26:48 The 3rd gear acceleration times from 4000 rpm to 7000 rpm were as follows: Modified Stock Muffler: 8.20 seconds Dyna: 7.83 seconds C-Bomb with Baffle: 7.81 seconds LCGP with 1.5" Baffle: 7.37 seconds Mac: 7.21 seconds Mac (black) packed: 6.72 seconds (added 11/22/20) LCGP with 1.75" Baffle: 6.68 seconds (added 12/16/20) C-Bomb: 5.79 seconds (Steam heat, tsssssssss!) As you can see, this engine wants a free-flowing exhaust system. The aggressive 340b cam really seems to work well with the unbaffled C-Bomb , the Black Mac, or the LCGP with 1.75" baffle. The trick will be to achieve free flow equivalent to the C-Bomb without making a lot of noise. Easier said than done. It will be interesting to see what happens when I try the open C-Bomb on the 97mm engine with its milder camshaft and larger exhaust port. I’m not suggesting that a free-flowing muffler on a stock engine will provide a similar improvement in acceleration. But on a highly modified engine, an engine that can take advantage of the free-flowing exhaust, you should expect a big gain. My engine obviously needs a better exhaust system. Lobbing 2.4 seconds off my acceleration time says it all. |
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Title: Re: Muffler Shootout Post by DragBikeMike on 11/11/20 at 22:27:48 Aesthetics? I’ll leave that up to you guys. I think all the systems look good in the right application. The stocker looks good on a sleeper. The Dyna looks good on a cruiser. The Mac looks good on a café. The C-Bomb looks good on a bobber. The LCGP looks good on an old school replica. For me, the clear winner overall is the LCGP. My goal is power and this one makes measurably more power without making a lot of racket. It achieves a low level of restriction without a high level of noise. It sounds good too. I believe there’s more flow to be had. That 2.5” glass-pack leaves enough room for a larger baffle tube (like 1.75” ID). I think I can get the restriction down to levels that are lower than the Mac. It would be great if I could come up with a muffler that pulls 16.5” H2O like the unbaffled C-Bomb, yet emits noise like the baffled LCGP. Dream on you say? Hey, ya gotta shoot for the stars, right? I hope some of you find this report informative. As always, I welcome your questions and comments. Stay safe, stay well. Mike |
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Title: Re: Muffler Shootout Post by SpamyToo on 11/12/20 at 00:48:01 Nice write up. Sure looks like fun. This bike makes some noise. 5 years back or so I won a loud bike contest at a show against all these Harleys with straight open pipes. It suppressed me the 650 was so loud with an aftermarket pipe, and made me realize I gotta quite down that stinking bike. |
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Title: Re: Muffler Shootout Post by Dave on 11/12/20 at 02:45:59 Good Write up and testing. A lot of folks just want their bike to sound faster, and don't really care if it actually is. Several other forum members who have installed Mac mufflers, including their Slash Cut model agree it is too loud. Any muffler you can see through is not going to be quiet! I do hope the Cherrybomb results don't start a "loud fad" in the pursuit of performance - your engine is highly modified and needs to breath! I wonder how well a SuperTrapp muffler would work on your bike? (Not trying to get you to spend more money). There was a SuperTrapp on my bike when I bought it - I took it off as it made too much noise for me. When I ride down the street I wave to my neighbors and they wave back.......they have all 4 fingers up! Maybe you could figure out a way to put a butterfly valve in the baffle tube.....and make it straight through and noisy when you need the power? |
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Title: Re: Muffler Shootout Post by Armen on 11/12/20 at 06:52:02 Wow! Another amazing job and write-up! thanks I too have the Mac system. Only run the bike on the side stand for a little while. Doesn't sound bad at idle, but I believe you about being loud when the bike is revved up. I bought a universal baffle and am trying to figure out how i want to fit it into the muffler. Of course, in the middle of this all, I moved, so the last few months of my life have been chaos. Looking forward to getting back to the project. thanks again |
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Title: Re: Muffler Shootout Post by verslagen1 on 11/12/20 at 08:35:51 You can get an app for smartphones that serves as decimeter. certainly your evaluation from quiet to loud is acceptable, but it would be nice to quantify it. |
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Title: Re: Muffler Shootout Post by bobert_FSO on 11/12/20 at 09:12:03 "You can get an app for smartphones that serves as decimeter." These apps can be wildly inaccurate. I saw somewhere that iphones have an upper response limit of of their response. I think it was somewhere around 105 db. Android phone apps can be wildly inaccurate because of all the mic and hardware differences between brands and models. If you happen to have a real meter, the app settings can be adjusted to match a known meter. |
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Title: Re: Muffler Shootout Post by verslagen1 on 11/12/20 at 10:23:29 Are wildly inaccurate as a human ear? |
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Title: Re: Muffler Shootout Post by LANCER on 11/12/20 at 10:26:24 Mike, what was the location of your vac gauge on your setup ? Did you also happen to get data using just one vacuum ? A 5hp test ? |
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Title: Re: Muffler Shootout Post by hotrod on 11/12/20 at 16:29:16 I like the Mac header, but am unable to find a seller to supply just the header itself. I don't want their muffler. :( |
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Title: Re: Muffler Shootout Post by DragBikeMike on 11/12/20 at 18:30:53 Dave, I guess the butterfly valve is an option. The Fastman also suggested that. However, I want the thing quiet at WOT too. In fact, WOT is where I really want it quiet. The last thing I want is to attract attention when I'm havin fun. Who knows, at some point I may have to relent if I want the best performance. Armen, I think you will regret the auxilliary baffle. The Mac core is already a bit small. Once you but an additional baffle in there the restriction will go through the roof. I'm planning on an attempt at packing the Mac. I have some ceramic wool that I want to try. I think I might be able to cut the muffler open and pack the area surrounding the core with that ceramic wool. I think that might reduce the high frequency noise. It will still be loud, but not so grating and obnoxious. Check out this video. It demonstrates how effective a combined approach is. The Mac uses restriction and small directional changes to scrub off the acoustic energy. Listen to what happens when I augment that with the glass packing (absorption). https://www.youtube.com/watch?v=_U91BRWUc6s Amazing isn't it. |
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Title: Re: Muffler Shootout Post by DragBikeMike on 11/12/20 at 18:34:52 Versy & Bobert, that smart phone app would be nice for comparative data. I wouldn't be too concerned about accuracy in terms of "exactly" how many decibels, but if I located the device in exactly the same proximity for every test it would be useful to compare one muffler to another. Unfortunately, I'm a flip-phone sorta guy. Do you think something like that is available for an iPad? |
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Title: Re: Muffler Shootout Post by DragBikeMike on 11/12/20 at 18:45:57 Lancer, I have old test data from May of 2018 where I used one 5.5 HP shop vac to test several mufflers. It was a different rig but I really can't imagine the rig would make much (if any) difference for this sort of test. With a single shop vac, the unmodified stock muffler pulled 35" H2O, the Dyna pulled 27.5" H2O, a Herritage muffler (non-catalyzed) pulled 31" H2O, and a SuperTrapp with 21 discs pulled 13" H2O. Regarding your question about where the manometer was tied in. The manometer is connected to the 4" ABS pipe. So the shop vacs tie in at the bottom, the manometer ties in at the center, and the muffler sits on top. The manometer reading is the difference between the two legs. If one side goes up 10", the other side goes down 10", so total difference is 20" H2O. I marked up this picture in red so you can see where the manometer ties into the rig. |
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Title: Re: Muffler Shootout Post by DragBikeMike on 11/12/20 at 18:50:30 HotRod, I agree that it would be nice to be able to buy just the header pipe. I had to buy two of these systems and all I wanted was the header. But all is not lost. Maybe the Mac muffler can be tamed. The fire-sale price that Dennis Kirk placed on the whole system made the pill a lot easier to swallow, even if it took a little work to get the header to slip into the head. |
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Title: Re: Muffler Shootout Post by Jdvt600 on 11/12/20 at 19:32:29 Amazing write-up, as per usual. Based on your review, the C-bomb w/baffle would be the winner for me. I like the look and prefer a bit of a growl in the exhaust note. Plus it also shaved a few pounds. Maybe I'll give it a go myself instead of saving for a supertrap. The supertrap although it has adjustability, seems a bit expensive. I've been struggling with the cost as it goes against the principal of the Savage for me. I'm guessing it's a fairly easy endeavor to fabricate your own baffle? Just search around YouTube and I'm set? |
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Title: Re: Muffler Shootout Post by LANCER on 11/13/20 at 09:16:40 Cone Engineering makes exhaust components Primarily with some ready made mufflers. You can choose the style/shape, length, width, mild or stainless steel, assorted types/sizes of baffles or NO baffle, type of mount; and pipe of course. Prices run about $150-185. Look at their parts and if what you want is there then it’s a good deal. I’ve used one for 15 years; love it. |
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Title: Re: Muffler Shootout Post by Ruttly on 11/13/20 at 11:23:07 DBM , If you didn’t build motorcycles you could have been an excellent MAD Scientist !? LOL |
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Title: Re: Muffler Shootout Post by LANCER on 11/13/20 at 16:27:56 321514140C19600 wrote:
Are you trying to say that you have stumbled on a secret identity of his ? [ch128527] |
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Title: Re: Muffler Shootout Post by DragBikeMike on 11/14/20 at 11:39:22 "MAD", of course. "Scientists", not so much. :o Verslagen, great suggestion on the decimeter. I love it. I was able to find a free NIOSH app for my iPad. I used it to take some readings with several of the mufflers installed. It was informative. These readings were taken with my garage door closed, bike sitting upright, iPad resting on the seat (same orientation for all mufflers). Took readings at 1300 rpm/3000 rpm/4000 rpm. LCGP with 1.5" baffle: 67/77/81 LCGP with 1.75" baffle: 69/79/81 Mac (chrome) : 70/83/86 Mac (black): 73/82/86 Mac (black) with packing: 70/80/83 C-Bomb with baffle: 64/78/81 C-Bomb no baffle: 71/83/85 Stock (modified): 63/80/82 If you compare these levels to NIOSH guidelines for noise exposure, it's pretty evident that the app isn't accurate. There's no way that NIOSH would permit unprotected exposure to any of these mufflers at 4000 rpm, so I suspect the actual noise levels are significantly higher. But the app is a great tool for comparison. The federal standard for the Dyna & Stock mufflers is 80 dB but I don't know what the test parameters are. |
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Title: Re: Muffler Shootout Post by verslagen1 on 11/14/20 at 12:13:54 fed std https://www.fs.fed.us/t-d/programs/fire/spark_arrester_guides/_assets/OHV209-308Blue.pdf the laws https://drivinglaws.aaa.com/tag/motorcycle-noise-limits/ |
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Title: Re: Muffler Shootout Post by Dave on 11/15/20 at 03:52:57 I believe that any recording, video or sound reading using a phone or video camera is pretty useless. The microphones on these little devices are made to record normal sounds, and loud sounds are clipped and made to sound "less loud" than they really are. If you doubt this just go listen to a recording of a "Top Fuel" dragster on YouTube.....the darn things take your breath away in person - but on the video they are no louder than a recording of any other engine with a loud muffler. I also believe that the sound of an engine "with full throttle and under load" is significantly louder than when it is revved up without any load applied. When my wife and I went to TN/NC one fall to see the colors and do some hiking, we walked on a trail at the Cherohala Skyway. We had walked about 30 minutes away from the road, and we could still hear the big V-Twins with open pipes - some of the really loud ones we could hear for 15 minutes as the noise just echoed down the valleys. There really should be an enforced "maximum" sound value on public roads......just as there should also be a "maximum" applied to the brightness of the added headlights (some of these fellows also install 5 or 6 LED headlights on their bikes). If you really want to record the db values I think you need a sound meter - but since the loudness numbers really don't mean much to us I am not sure if it is any more informative than your "opinion". Most of the people who have installed a MAC muffler on a Savage have removed them as they are just too loud......unless you are a hard core noise maker! |
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Title: Re: Muffler Shootout Post by antmanbee on 11/15/20 at 05:47:47 For relative loudness, I would test out doors in an open space with nothing to reflect the sound as much as possible. Then measure from the exhaust outlet, a meter or 2 meters or 3 meters or to whatever distance that the phone mic is not being overloaded. Maybe put the phone a few feet above the ground too. |
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Title: Re: Muffler Shootout Post by LANCER on 11/15/20 at 10:07:53 I know this varies state by state but an HP officer told me the decibel level is measured 25’ from and at a 45^ angle from the rear of the bike, out in the open, with the engine at idle. I think that was in SC . |
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Title: Re: Muffler Shootout Post by DragBikeMike on 11/15/20 at 16:32:37 "I believe that any recording, video or sound reading using a phone or video camera is pretty useless." Dave, I agree that this App is probably not accurate in terms of meeting a specification or compliance with laws, but I think it is an excellent tool for a hobbiest trying to come up with a good flowing quiet muffler. It allows you to actually quantify the difference when you make a change. I think it works great for that. It's no longer simply my opinion of the noise level, I actually have a way to measure the noise level. As long as I always take the readings under the same conditions and parameters, it should tell me what works and what doesn't. Versy, again thanks for the tip and also for the links on laws and test procedures. For info, I tried the procedure that specifies placing the iPad twenty inches from the exhaust outlet at a 45 degree angle. I only did that with the LCGP muffler. The values went up a bit. 73/79/82 I suspect that all of the mufflers I tested would show increased noise with this test (20 inches, 45 degrees). I'm very pleased with how quiet this muffler is. The bike runs great and sounds even better. I'm gonna try a larger baffle tube. I will post the results. |
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Title: Re: Muffler Shootout Post by DragBikeMike on 11/22/20 at 22:06:55 11/22/20 While I am waiting for materials to enlarge the baffle tube on the LCGP muffler, I decided to try and quiet down the Mac muffler. I have two, a chrome one and a black one. Since the mods I was planning require that the muffler be cut open, I decided to work on the black Mac. I can’t touch up chrome with paint. I wanted to make sure I did a fair comparison, so I threw the Black mac on the test bench to make sure it pulled close to 32-1/2” H2O like the chrome Mac. To my surprise, the Black Mac only pulled 26” H2O. I spent a while swapping the two mufflers back & forth on the bench. Chrome 32-1/2” H2O, black 26” H2O, over & over. What’s up with that? I placed the two mufflers side by side. It was evident that they are different. The black one is shorter. |
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Title: Re: Muffler Shootout Post by DragBikeMike on 11/22/20 at 22:08:11 11/22/20 While I am waiting for materials to enlarge the baffle tube on the LCGP muffler, I decided to try and quiet down the Mac muffler. I have two, a chrome one and a black one. Since the mods I was planning require that the muffler be cut open, I decided to work on the black Mac. I can’t touch up chrome with paint. I wanted to make sure I did a fair comparison, so I threw the Black mac on the test bench to make sure it pulled close to 32-1/2” H2O like the chrome Mac. To my surprise, the Black Mac only pulled 26” H2O. I spent a while swapping the two mufflers back & forth on the bench. Chrome 32-1/2” H2O, black 26” H2O, over & over. What’s up with that? I placed the two mufflers side by side. It was evident that they are different. The black one is shorter. |
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Title: Re: Muffler Shootout Post by DragBikeMike on 11/22/20 at 22:10:04 It turns out the Black Mac has a larger diameter core. It’s not evident because the core is stepped. The part that sticks out is the same size as the chrome Mac, but the long internal section, the section with all the louvers, is much larger. Good for flow, but how about noise? A quick test on the bike and I had the answer. It sounds a bit louder, but the frequency of the noise is much lower than the chrome Mac. It sounds a lot better, but it’s still way too loud, in the same league as the C-Bomb. 73/82/86 dB I was able to successfully cut it open and pack it with ceramic wool. That reduced the noise a bit. I can ride it around the neighborhood if I take it easy on the throttle. It’s pretty quiet when its idling. Still too loud for me but I’m sure it would be acceptable to some of you. Seems the packing lobbed off about 3 dB and mellowed out the frequency a bunch. It sounds good, but loud. 70/80/83 dB It runs great. With the Black mac installed it pulls the 3rd gear 4K to 7K in 6.72 seconds. There’s a lot of steam. Not as speedy as the C-Bomb, but at least you can ride it around the neighborhood. I will be doing a post to give all the details on cutting it open and filling it with packing. For those of you that purchased the Mac System from Dennis Kirk, if it’s the Black Mac, the one with the oversize flange, you probably have the same muffler. If you have the smaller core, the mods I did will probably work good on that one too, it just won’t be as fast. To satisfy my curiosity, I threw the modified stock muffler on so I could measure its noise output. It was the quietest unit at idle, but the C-Bomb with baffle and the LCGP with baffle were quieter at 3000 & 4000 rpm. That surprised me. 63/80/82 dB So I will forge ahead with my plan to install a larger diameter baffle in the LCGP and see if I can get the flow closer too or better than the Mac. More to come. |
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Title: Re: Muffler Shootout Post by Edub on 12/16/20 at 16:44:53 Wow, this was an amazing read! Really interesting to hear about your findings. I never would have thought about an automotive cherry bomb muffler! They practically give those away! I do have a question, there's something I may have missed. The baffles you made for the cherry bomb and the other straight through muffler had fittings on each end to facilitate mounting. What are these? Did they come from the mufflers themselves? Also, how did you accomplish the mid-baffle "diverter"? I don't recall the exact term you used, but what is it, how did you install it? Sorry for so many questions, but this is really interesting stuff. |
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Title: Re: Muffler Shootout Post by DragBikeMike on 12/17/20 at 01:32:50 Edub, I call the pieces at each end of the baffle tube "adapter bushings". I'm not sure that is the correct terminology but I like it. They keep the baffle centralized and seal the baffle tube OD to the muffler core ID. They can be made from any suitable material that can take the heat (not aluminum, found that out the hard way). I refer to the mid-baffle diverter as a "plug". Its simply a solid piece of metal. I lock it in place with a bolt that goes all the way through the baffle tube & plug. I will be doing a post on constructing the LCGP HiFlow Quiet Muffler. The techniques would be the same for the Cherry Bomb. I finished the LCGP with the larger baffle tube. It worked great. All the tables I previously posted in this thread have been updated. The 1.75" baffle tube is a lot less restrictive. It runs significantly faster which indicates more horsepower. It is also still very quiet and has a very satisfying, low frequency exhaust note. While testing the new LCGP, I noticed I was using a lot less fuel. Fuel mileage is not at the top of my priority list but it was such a dramtic difference that I was compelled to accurately check it. Prior to the HiFlow muffler the best mileage I had achieved with this engine was 59 mpg (during the carburetor shootout). Now it gets 63 mpg. That sruprised me so I checked it several more times. It gets an honest 63 mpg riding in a normal fashion. That means not trying to milk every last mpg I can. Just rode it. I think that's pretty darned good considering the bump stick I'm runnin. |
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Title: Re: Muffler Shootout Post by Edub on 12/17/20 at 11:01:17 Very cool! I hope you can post some video/audio files with your findings; I’d love to hear the quieter solutions that perform well. I’d also love to see some detailed fabrication process images of how you made these bushings and the other parts; I’m a decent welder, but I don’t have much experience with a lathe or milling machine, so having a better idea of how you made these smaller, critical components would be really interesting. |
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Title: Re: Muffler Shootout Post by sparktfxr on 12/17/20 at 14:21:03 Hi Mike, always look forward to reading of your experiences, I also spent a bit of time modifying mufflers for both looks & sound on the S40 (mostly with unsuccessfull sound reduction) with a 17 inch reverse cone type muffler with a removable cone. One thing which did seem to take the sharp crack out of the note was a piece of curved pipe fitted at the exit of the muffler curving up & pointing the sound down more towards the ground than straight out. I got the idea from a guy who had them fitted to his 850 Norton Which just seemed to whisper along. Thanks for all your very helpfull input. |
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