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/cgi-bin/YaBB.pl General Category >> Rubber Side Down! >> HighFlo Quiet Muffler Details /cgi-bin/YaBB.pl?num=1609379913 Message started by DragBikeMike on 12/30/20 at 17:58:33 |
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Title: HighFlo Quiet Muffler Details Post by DragBikeMike on 12/30/20 at 17:58:33 In November of 2020 I did a muffler shootout. It was fun and I proved that a free-flowing muffler can make a huge difference in performance. Although the muffler I was running (modified stock muffler) flowed better than a stock muffler, it left a pile of horsepower and fuel efficiency on the table. A free-flowing muffler was in order, but it had to be quiet. As it turns out, it’s not too difficult to build a HiFlow Quiet Muffler. The new HiFlow muffler is based on an automotive resonator. It flows much better and is quiet as a church mouse. It lobs a whopping 1.52 seconds off my acceleration time (3rd gear 4K to 7K) and gets 63 mpg in the bargain. What’s not to like about that? It’s cheap too. This post provides the general details on the construction of a HiFlow quiet muffler. Let’s get started. |
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Title: Re: HighFlo Quiet Muffler Details Post by DragBikeMike on 12/30/20 at 17:59:36 The foundation for the HiFlow muffler is LCGP’s 2.5” stainless-steel automotive resonator, model 254019. You can find one on Amazon for $36 bucks. It’s a high-quality item, polished stainless steel, light weight, and has nice welds. |
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Title: Re: HighFlo Quiet Muffler Details Post by DragBikeMike on 12/30/20 at 18:00:17 Dimensions: |
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Title: Re: HighFlo Quiet Muffler Details Post by DragBikeMike on 12/30/20 at 18:01:01 This shows the construction (structural analysis not so much, how it’s constructed yes). It’s a straight through design, a full 2-1/2” all the way through. It relies solely on absorption to attenuate the acoustic energy. It’s packed with one layer of stainless-steel mesh and one layer of glass fiber cotton. The packing is captured with a stainless-steel grid. |
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Title: Re: HighFlo Quiet Muffler Details Post by DragBikeMike on 12/30/20 at 18:02:28 The design of the HiFlow Quiet muffler utilizes three methods of noise reduction: restriction, direction change, and absorption. A baffle tube is used to restrict flow and force the hot gas to change direction. The stainless-steel mesh and packing material in the LGCP resonator perform the absorption. This illustration shows the flow path. Hot gas enters the baffle at chamber “A”. A plug in the center of the baffle forces the hot gas to turn and flow outward through perforations in the baffle. The hot gas then enters chamber “B” where it turns again and flows toward the rear of the muffler. Acoustic energy is absorbed by the packing that surrounds chamber “B”. The hot gas then turns again and flows through the perforations in the baffle into chamber “C”. Finally, the hot gas turns again and exits the baffle tube. This system is highly effective at reducing noise. It also flows well. My tests show the restriction is low compared to a Dyna or a modified stock muffler. In terms of flow, it rivals the Mac muffler, which is a very loud straight-thru design. |
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Title: Re: HighFlo Quiet Muffler Details Post by DragBikeMike on 12/30/20 at 18:04:12 The 2-1/2” core lends itself to installation of a large diameter baffle. There’s plenty of room for the hot exhaust gas to flow out of the baffle and through the muffler. During the muffler shootout I tried a baffle with a 1.52” ID. It worked well but I wanted more flow. So, the next iteration of the HiFlow design got a baffle with a 1.65” ID. That seemed just about right. On the test bench, the larger diameter baffle reduced the depression from 33-1/2” H2O to 31-1/2” H2O. In comparison, the Mac chrome reverse cone muffler pulled 32-1/2”. The area of the cross section of the baffle ID (“A”) must be close to the area of the cross section of the void between the baffle outside diameter (OD) and the resonator core ID (“B”). If you use a baffle with a larger ID it reduces the cross section of the void. So, if you increase the baffle diameter too much the void gets too small and flow is degraded. The final cross sections were 2.14 in2 (“A”) vs 2.50 in2 (“B”). That was close enough for me. |
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Title: Re: HighFlo Quiet Muffler Details Post by DragBikeMike on 12/30/20 at 18:05:15 The baffle is fabricated from a 1.75” tail pipe. It has a 1.65” ID and a 1.75” OD. It is 18” long. This item came from AutoZone. The AutoZone part number is 17621. |
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Title: Re: HighFlo Quiet Muffler Details Post by DragBikeMike on 12/30/20 at 18:06:05 The size and number of perforations must be determined. No sense making any more holes than necessary. More holes equal more noise. Test the baffle tube to determine the point where adding more holes doesn’t increase flow. It’s a simple test. Close off one end of the tube and start sucking on the other end with a test rig. Two big shop vacs work well. With 36 holes this one pulled 34-1/2” H2O. Keep adding holes in increments of 12 until you see the improvement start to flatten out. It looked like 108 holes on each side of the center plug would be the sweet spot. Here’s a look at the baffle perforation test. |
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Title: Re: HighFlo Quiet Muffler Details Post by DragBikeMike on 12/30/20 at 18:06:51 You can see on this graph that the curve starts to flatten at about 96 holes and it’s pretty much done by 120 holes. I chose 108 holes for my sweet spot. I think any more than 108 holes will only add noise, it won’t reduce back pressure or increase flow. Each perforation was made with a 11/64” drill bit (about .17”). It takes a while. |
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Title: Re: HighFlo Quiet Muffler Details Post by DragBikeMike on 12/30/20 at 18:16:47 While on the subject of back-pressure. I hear a lot of banter about back-pressure and how your engine needs back-pressure and how exhaust systems with no back-pressure kill torque….. I say baloney. David Vizard has a great cliché. “The best performance muffler is no muffler at all.” Yes, you can screw up street manners with a straight pipe, but that’s not a result of no back-pressure. It’s due to a resonant wave returning to the exhaust valve while the valve is still open. All you need is something to break up the resonant wave (like a baffle or slight reduction in pipe size). The baffle will inherently increase exhaust pressure a bit. The trick is to come up with a system that can reduce noise, break up the resonant wave, and allow the highest possible flow. This is a great video. Engine Masters does some cool dyno testing on exhaust systems. There’s a part in the video where they talk about back-pressure. If you pay close attention you will see they are being sarcastic, joking about the back-pressure myth. Ultimately, they prove how the less restrictive exhaust system is pretty much better everywhere. The Power of 2.5- vs. 3-Inch Exhaust - Engine Masters Ep. 9 - YouTube https://www.youtube.com/watch?v=_PVXvHkr-Vs Oh well, looks like the link won't work but I bet if you Google "Engine Masters Episode 9" it will get you there. |
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Title: Re: HighFlo Quiet Muffler Details Post by DragBikeMike on 12/30/20 at 18:21:04 This sketch identifies the various pieces needed to construct the LCGP HiFlow muffler. Any similar glass-pack muffler could be used. If you use a muffler smaller than 2-1/2” the baffle size will have to be adjusted accordingly, and the number and size of perforations will also need to be adjusted. Anything larger than 2-1/2” and similar adjustments will be necessary. I personally think that 2-1/2” is the optimum size for the LS650. I use a Mac header pipe. If you want to install the muffler on a different header pipe you will need to use a different reducer (item 7) to suit the header and you may need to bend or kink the reducer to accommodate the angle of your header. Item 1 is the LCGP 2-1/2” Stainless Steel Resonator 254019 $36 Item 2 is the packing material (can’t be replaced) Item 3 is the baffle tube, AutoZone 1.75” tailpipe 17621 $13 Item 4 is adapter bushing exit end, made from Lincoln 2” x 1.5” pipe bushing 440333 $13 Item 5 is baffle plug, made from Lincoln 1.5” pipe plug 440088 $6 Item 6 is adapter bushing inlet end, made from Lincoln 2” x 1.5” pipe bushing 440333 $13 Item 7 is exhaust reducer, 2.5” OD x 2.0” ID, ROL200ID250OD $9 So, for $90 bucks and some elbow grease you can construct a quiet muffler that sounds great and hauls freight. |
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Title: Re: HighFlo Quiet Muffler Details Post by DragBikeMike on 12/30/20 at 18:21:54 Here is the raw material needed for the adapter bushings and the inlet reducer. It’s all pretty much routine hardware. The galvanized pipe bushings should be available at any hardware store, and the exhaust reducer is available at most auto parts store. |
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Title: Re: HighFlo Quiet Muffler Details Post by DragBikeMike on 12/30/20 at 18:22:55 The inlet adapter bushing is 2.53” OD by 1.85” ID by 3/8” thick. It can be made from the pipe bushing I list or any other ferrous material you can scrounge up (pipe cap, large washers, scrap steel plate, scrap steel pipe, etc.). It’s not critical. It just has to keep the baffle tube centralized and block off exhaust gas from flowing around the baffle. Here’s a shot of the rough-out. |
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Title: Re: HighFlo Quiet Muffler Details Post by DragBikeMike on 12/30/20 at 18:23:35 This is the finished inlet adapter bushing. Note the chamfer. This bushing gets permanently installed in the 2 x 2.5 reducer. The chamfer is there to help guide and align the baffle tube when you slide it into the muffler. The baffle tube has a slip-fit with the inlet adapter bushing to accommodate expansion. The baffle will run hotter than the muffler body and it will expand more. The slip fit lets it grow without causing any undue stress. |
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Title: Re: HighFlo Quiet Muffler Details Post by DragBikeMike on 12/30/20 at 18:24:17 Here is the inlet adapter slipped over the baffle tube. Because of the female socket in the tailpipe, the OD of the pipe in way of the adapter bushing is 1.85” instead of 1.75”. |
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Title: Re: HighFlo Quiet Muffler Details Post by DragBikeMike on 12/30/20 at 18:25:09 Here is the inlet adapter bushing installed in the 2 x 2.5 exhaust reducer. It’s a snug fit (lite drive fit). It gets locked in place by two 8-32 countersunk screws. Once the reducer is installed in the muffler, it’s permanent. It’s not easy to remove once the muffler is assembled. The large hole in the side of the reducer is for my O2 sensor. If you’re not running an air/fuel ratio meter you don’t need the hole. |
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Title: Re: HighFlo Quiet Muffler Details Post by DragBikeMike on 12/30/20 at 18:26:00 The adapter bushing on the rear end (outlet end) is similar to the inlet end. It is 2.53” OD by 1.75” ID by 3/8” thick. It gets permanently fixed to the baffle tube with two 8-32 countersunk screws. Here you see it slipped over the baffle tube. |
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Title: Re: HighFlo Quiet Muffler Details Post by DragBikeMike on 12/30/20 at 18:27:17 Here’s how the adapter bushing is fastened to the baffle tube with countersunk screws. |
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Title: Re: HighFlo Quiet Muffler Details Post by DragBikeMike on 12/30/20 at 18:27:57 The baffle is about ready for perforations. You can see the exit end will need to be trimmed slightly. |
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Title: Re: HighFlo Quiet Muffler Details Post by DragBikeMike on 12/30/20 at 18:28:50 The center plug is carved out of a 1-1/2” galvanized pipe plug, another routine item available at most hardware stores. |
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Title: Re: HighFlo Quiet Muffler Details Post by DragBikeMike on 12/30/20 at 18:29:36 It’s set up with a light drive fit into the 1.65” ID baffle tube, then drilled through for a ¼-20 bolt and nut. |
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Title: Re: HighFlo Quiet Muffler Details Post by DragBikeMike on 12/30/20 at 18:30:15 The plug looks like this once its installed. It will force the hot exhaust gas to flow out through the perforations in the baffle tube. |
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Title: Re: HighFlo Quiet Muffler Details Post by DragBikeMike on 12/30/20 at 18:30:56 The baffle tube and plug are drilled to accept a ¼” bolt. The bolt locks the plug in-place. |
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Title: Re: HighFlo Quiet Muffler Details Post by DragBikeMike on 12/30/20 at 18:31:40 There are a total of 216 holes drilled in the baffle, 108 on each side of the plug. The holes are 11/64” (.17”). A drill-press works good but a hand-held drill will get the job done. Make sure to clean up all the burrs. |
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Title: Re: HighFlo Quiet Muffler Details Post by DragBikeMike on 12/30/20 at 18:32:28 The 2 x 2.5 exhaust adapter will need two slots cut so the muffler clamp can pinch it tight onto the header pipe. A Harley muffler clamp is in order, they are heavy duty and get the job done. Start the slots with a hacksaw and then finish up with a flat file. An exhaust pipe expander works good for holding the reducer while making the cuts. |
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Title: Re: HighFlo Quiet Muffler Details Post by DragBikeMike on 12/30/20 at 18:33:12 The exhaust pipe expander works great for holding the work piece. It also comes in handy for installing the baffle into the muffler. You don’t need to tighten it very much, just enough to grip the pipe, not enough to expand the pipe. |
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Title: Re: HighFlo Quiet Muffler Details Post by DragBikeMike on 12/30/20 at 18:34:02 If you run an O2 sensor you will need a bung. I don’t have welding equipment so I make bungs that can be mechanically installed. Grade 2 bolts & nuts work good. |
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Title: Re: HighFlo Quiet Muffler Details Post by DragBikeMike on 12/30/20 at 18:34:38 To accommodate the O2 sensor bung you have to drill a 1” hole through the muffler and the reducer. The thin wall material requires that you use a hole saw or a step drill. Step drills work really good and they don’t tear up the thin wall material. |
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Title: Re: HighFlo Quiet Muffler Details Post by DragBikeMike on 12/30/20 at 18:35:21 You end up with this. All lined up and ready for the bung. |
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Title: Re: HighFlo Quiet Muffler Details Post by DragBikeMike on 12/30/20 at 18:36:08 When it’s ready for final assembly, pile on the JB Weld Extreme Heat Paste and insert the bung through the inside. Apply more paste to the threads and install the threaded collar. The small bolt and nut are only used to hold the bung in place while tightening the collar, then remove the nut and pull the bolt out from the inside. |
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Title: Re: HighFlo Quiet Muffler Details Post by DragBikeMike on 12/30/20 at 18:36:54 When it’s all finished the bung looks like this. It works fine. No leaks. A little simichrome cleans up the excess JB Weld paste on the bung and polished stainless-steel. |
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Title: Re: HighFlo Quiet Muffler Details Post by DragBikeMike on 12/30/20 at 18:37:46 A ¼-20 stainless-steel button head screw is used to secure the other side (bottom) of the reducer to the muffler. If an O2 sensor bung is not installed, substitute a ¼-20 stainless-steel button head screw on the top to lock the reducer to the muffler. The joint between the reducer and muffler is sealed with JB Weld Extreme Heat paste. Once it’s all together, it’s not advisable to try and take it apart. You must make sure everything is right before you assemble it. Several dry fit-ups are in order before final assembly. Before you assemble the reducer to the muffler, make sure the adapter bushing is installed in the reducer. This shows the ¼-20 screw installed in the bottom of the joint. |
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Title: Re: HighFlo Quiet Muffler Details Post by DragBikeMike on 12/30/20 at 18:38:33 Install the baffle tube into the muffler. As mentioned earlier, the exhaust pipe expander comes in handy to slide the baffle into the muffler and align the screw holes. |
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Title: Re: HighFlo Quiet Muffler Details Post by DragBikeMike on 12/30/20 at 18:39:25 Lock the baffle assembly in the muffler with suitable stainless-steel screws. The screws are threaded into the adapter bushing. Stainless-steel countersunk screws (8-32) fit just right. Put a dab of Permatex Optimum Black or Grey sealant on the threads prior to installing the screws. It keeps the screws from coming loose. The Permatex Optimum grade sealants can take the heat. |
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Title: Re: HighFlo Quiet Muffler Details Post by DragBikeMike on 12/30/20 at 18:40:14 A modified Mac muffler bracket works fine. Any similar fabrication will work. You can make if from 1/8” steel plate or angle. Just drill some holes and bend it to suit. Attach the bracket to the muffler with 5” stainless-steel hose clamps. It’s strong and looks OK. This one has about 500 miles on it. So far, no problems. |
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Title: Re: HighFlo Quiet Muffler Details Post by DragBikeMike on 12/30/20 at 18:40:59 Maybe later I will see if I can come up with a mount that can be attached to the muffler with stainless-steel pop-rivets. |
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Title: Re: HighFlo Quiet Muffler Details Post by DragBikeMike on 12/30/20 at 18:42:05 The LCGP muffler looks good on the bike. The sound is very pleasing and it’s not loud at all. There’s measurably more power and the fuel economy has improved too. It’s also about 8 pounds lighter than the stock muffler. At $90 this thing provides good bang for the buck. |
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Title: Re: HighFlo Quiet Muffler Details Post by Armen on 12/30/20 at 20:40:01 Awesome! Thanks for sharing your hard work! |
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Title: Re: HighFlo Quiet Muffler Details Post by LANCER on 12/31/20 at 15:41:07 Very interesting Mike, thanks. |
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Title: Re: HighFlo Quiet Muffler Details Post by Mavigogun on 01/02/21 at 19:35:43 Fantastic write-up, Mike- I suppose all your tube diameters complement your large bore cylinder? I've got a stock header and a carb jetted to a Harley muffler- all that talk about no flow being too much- were you speaking to your circumstance, or mine? "Unlearning" a truism, I seem to be resisting adjustment. |
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Title: Re: HighFlo Quiet Muffler Details Post by Hiko on 01/02/21 at 23:11:45 Very interesting Mike It almost seems too easy and begs the question Why aren,t all mufflers made that way? Thanks for sharing |
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Title: Re: HighFlo Quiet Muffler Details Post by DragBikeMike on 01/03/21 at 02:04:28 Mavigogun, I did all the tests on my 94mm engine. Once I finished up with the muffler project, I pulled the 94mm engine and installed the 97mm. The 97mm runs great with this muffler too, but the improvement is not nearly as dramatic as it was on the 94mm. I'm not sure why. The two engines have different cams and exhaust ports. The 94mm has a hotter cam and a smaller exhaust port, while the cam in the 97mm is a lot milder but the exhaust port is larger. It could be that the bigger bore engine wants a muffler that flows more, or the smaller engine has a cam that works better with this muffler. However, the muffler works superb on either engine. Regarding the flow, I'm a firm believer in achieving the highest flow possible without setting up a reversion problem. No sense installing a bunch of high performance components and then choking off the exhaust. Big carburetors, cams, porting, air filters are all intended to move more air through the engine. How can choking off the exhaust system help? My best acceleration times were using a wide open cherry bomb glass pack. It was only .04" (1mm) smaller in diameter than the header. Street manners were just fine, not a hint of reversion. Must not take much to break up the resonant wave. Hiko, many mufflers are made exactly like this one. A good example is the Dyna muffler. It uses a similar baffle design and absorbent material in the outer shell. But the baffle diameter is a lot smaller and there are fewer perforations in the baffle. These reductions are necessary to allow the muffler to meet federal standards. Both the stock LS650 muffler and the Dyna muffler have notes stamped into their shell stating that the muffler meets a federal standard of 80 dB. This HighFlo muffler is quiet but I don't think it meets that standard. It is certainly quieter than any other aftermarket muffler I have heard. |
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Title: Re: HighFlo Quiet Muffler Details Post by MMRanch on 06/09/21 at 00:43:07 Nice job Mike ! good looking on the bike too ! 8-) I'm guessing the inside dia. of the head pipe is the biggest restriction ? My best acceleration times were using a wide open cherry bomb glass pack. I'll be trying out the "wide open cherry bomb" thing when the mail person gets here with it !. :) |
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Title: Re: HighFlo Quiet Muffler Details Post by DragBikeMike on 06/09/21 at 11:05:03 Good luck with the wide open muffler MMRanch. I suspect it's gonna be a bit on the loud side. I put an additional baffle in a 1.75" cherry bomb and it took the bite right out of it. Unfortunately, the additional baffle also brought the flow down to the same level as a Dyna muffler. It ran good and sounded good, but just didn't have the flow I was looking for. It's the size of the baffle. You can only fit about a 1" baffle tube in that 1.75" muffler. |
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Title: Re: HighFlo Quiet Muffler Details Post by DragBikeMike on 06/09/21 at 11:13:19 The 1.75" muffler just doesn't have enough cross section to permit a properly sized baffle tube. Let us know how yours works out. Post some pictures so we can see what you come up with. These glass pack mufflers are easy to modify and the results are well worth the effort. |
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Title: Re: HighFlo Quiet Muffler Details Post by MMRanch on 02/14/22 at 10:06:01 I don't think I demand as much performance from my bike as some of you other folks. But That MPG sure looks good ! :) ................ Here's the 1.75 pipe I'm putting on it , it is a foot and a half long ! :) . |
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Title: Re: HighFlo Quiet Muffler Details Post by TheSneeze on 02/14/22 at 11:38:00 I noticed you are in Lynchburg. The Jack Daniels Distillery is on my bucket list to visit. It has been my favorite bourbon for decades! |
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Title: Re: HighFlo Quiet Muffler Details Post by justin_o_guy2 on 02/14/22 at 15:38:20 716E4B4C464F435049220 wrote:
Visiting a distillery would be cool. Go. Do that. But, try Tullamore Dew,Irish whiskey. After you tour the American whiskey producers. Or you might stay home. |
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Title: Re: HighFlo Quiet Muffler Details Post by Kwarran on 01/04/23 at 05:41:00 Great guide, I think I will make one of these for my bike. Any chance you can record a sample so we can hear how the muffler sounds? I have to choose between this muffler and a Screamin Eagle, any ideas if the Screamin Eagle has comparable flow? |
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Title: Re: HighFlo Quiet Muffler Details Post by DragBikeMike on 01/04/23 at 13:07:40 I believe the Screamin Eagle will have good flow but also suspect it will be very loud. They are a fairly simple design with a simple baffle, no glass wool. If your goal is to achieve a good sounding bike, you can forget about it. These big singles don't sound good. You will never get that V-Twin rumble. But if you want to make good power and improve fuel economy, then a free-flowing exhaust will help a lot. If you want the good power and improved fuel economy without making a bunch of obnoxious noise, then this muffler, or one with a similar design, will do the job. This is a recording of the LCGP muffler in the garage. This particular muffler has a 1.5" baffle. There's a bit of chirp. The 1.65" baffle (1.65" ID x 1.75" OD) eliminates the chirp, but the sound quality and volume are about the same. https://www.youtube.com/watch?v=m1e0M3u7i0M&feature=youtu.be This is the same muffler on a country road cruisin through the gears. You can see that the engine revs free but doesn't make a lot of useless noise. You can make lots of power without offending all the other motorists, scaring wildlife, and being obnoxious. https://www.youtube.com/watch?v=kkcUdPD0g_c&feature=youtu.be Here it is on the feeway. You can barely hear it over the road noise and wind. https://www.youtube.com/watch?v=z7TGA-43JaA&feature=youtu.be You don't have to use the LCGP muffler to make one of these. Any decent 2.5" glass pack will work as long as it has the same basic dimensions. If you make the baffle tube just like the one shown in this post, and perforate it with the same number of holes and the same size holes, it should perform just as good. |
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Title: Re: HighFlo Quiet Muffler Details Post by Kwarran on 01/10/23 at 04:41:11 Sweet, sounds badass. Thank you very much for the reply and info! I'll go with the LCGP muffler for sure. |
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Title: Re: HighFlo Quiet Muffler Details Post by ThumperPaul on 01/12/23 at 06:21:45 Afterfire problem solved! As usual, impressive work Mike! |
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Title: Re: HighFlo Quiet Muffler Details Post by LANCER on 10/29/23 at 11:27:49 677C667D717F2527242D140 wrote:
Ive tried several Screaming Eagles in years past and all of them were problematic. The sound level was extreme and sound quality was very harsh. Tuning them was like trying to tune a straight pipe, it was generally an exercise in futility. They did flow a lot of air though. I do not use them any more. |
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Title: Re: HighFlo Quiet Muffler Details Post by LANCER on 10/29/23 at 11:30:10 [img][/img] 5C607D65786D7A58697D64080 wrote:
I think we might need to downsize these pipes a bit to make them work on the LS650. |
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