Donate!
Welcome, Guest. Please Login or Register :: View Members
Pages: 1 2 3 4
Send Topic Print
Stock Muffler Eval & Upgrade (Read 546 times)
DragBikeMike
Serious Thumper
*****
Offline

SuzukiSavage.com
Rocks!

Posts: 4071
Honolulu
Stock Muffler Eval & Upgrade
05/15/18 at 23:58:01
 
This post will take awhile.  I have lots of pictures to insert and it will take me multiple replies to complete.  Please hold off on any comments until I finish the initial portion of the thread so it will make sense.  I will state that I’m finished with the initial report when I finish up.

I wanted to evaluate and test the stock muffler to see if I could improve the flow without dramatically increasing audible noise.  I also want to be able to return the thing to stock condition if possible, so I will be doing any modifications in stages, testing for flow and noise level after each stage is complete.  Todays post covers stage I.

I was able to reduce the restriction from 35” H2O to 29” H2O.  It’s still very quiet (pretty much like stock).  It runs good.  It was inexpensive to modify.  It looks pretty much the same.  It was quite a bit of work (but don’t forget I was doing lot’s of inspecting & measuring & testing along with the mods).  It’s not as easy as installing a Dyna muffler.

What I did was similar to the “Hartman Modification” discussed in the tech section.  You can find more details on that mod at jonline.org/savage/Tips.  The difference between the Hartman Mod and the DBM mod is I stick to the stock flow path through the muffler.  I don’t claim that this is any sort of “tuned” system, it’s simply less restrictive.

I know most of you have no interest in utilizing the stock muffler.  Some think it is ugly.  Others don’t care for the sound.  Some are concerned with the weight.  I personally find the animal a thing of beauty.  Not necessarily because of how it looks (however I do think it looks pretty good), but because of the potential associated with it’s volume.  It’s very large, much larger than say a Harley Dyna unit, or a SuperTrap.

If you do a mathematical evaluation of just the cylindrical portion of the stock LS muffler (4.15” OD x 11” long) to just the cylindrical portion of the Dyna muffler (3.25” OD x 13” long) you will see that the LS muffler has 41 cubic inches more internal volume than the Dyna.  Peek inside of the mufflers and you will see that the conical section of the LS muffler has way more volume than the Dyna.  Also, keep in mind that Harleys (most models) use exhaust systems where each cylinder shares two mufflers.  They use a crossover pipe so that each individual cylinder is actually connected to two mufflers.
 
I think that the volume of the muffler makes a significant difference in how well the device can do it’s job (allow maximum flow while effectively attenuating noise).  That extra volume allows the hot gasses to accumulate without building up excessive pressure.  There’s nominally 500 degrees of crank rotation before the next slug of hot gas comes down the pike so that extra volume is a nice place to store the stuff while it meanders out the back door.  

Next time you pull up behind one of those new racy Camaros, take a look at those two, beautiful, stainless steel works of art hanging under the car.  They are huge.  How about any of those late model sport bikes like say a Hayabusa, GSXR, ZX-10, R1 or RR1000.   They all have very large-volume muffler systems.  Totally stock, those machines all make big horsepower and are quiet.  Buell designed the eighth wonder of the world when he came up with that magnificent (albeit not too pretty) 55 gallon drum hanging off the bottom of the engine.  It received accolades from the motorcycling press for affording excellent performance and lowering the center of mass while meeting federal noise standards.    It also had this innovative valve system that opened up additional portions of the muffler under WOT conditions.  Majorly cool Erick.  Now corvette just happens to have a valve system like that.

I’m not a muffler designer so I just sort of made up my own names for the various components.  Please forgive me if the names I assigned turn out to be in disagreement with the actual name of a particular part of the muffler.

Let’s get started.
Back to top
 
 

Knowledge is power.
  IP Logged
DragBikeMike
Serious Thumper
*****
Offline

SuzukiSavage.com
Rocks!

Posts: 4071
Honolulu
Re: Stock Muffler Eval & Upgrade - Stage II
Reply #1 - 05/16/18 at 00:00:33
 
I removed the muffler and hooked it up to my poor man’s flow bench.  The stock muffler restricted flow enough to register 35” H20 on the water manometer (almost pulled it right off scale).  It was the same with or without the header pipe.

[img][/img]
Back to top
 
« Last Edit: 05/30/18 at 23:17:30 by DragBikeMike »  

Knowledge is power.
  IP Logged
DragBikeMike
Serious Thumper
*****
Offline

SuzukiSavage.com
Rocks!

Posts: 4071
Honolulu
Re: Stock Muffler Eval & Upgrade
Reply #2 - 05/16/18 at 00:01:40
 
Let's try that image again.

[img][/img]
Back to top
 

IMG_02491.JPG

Knowledge is power.
  IP Logged
DragBikeMike
Serious Thumper
*****
Offline

SuzukiSavage.com
Rocks!

Posts: 4071
Honolulu
Re: Stock Muffler Eval & Upgrade
Reply #3 - 05/16/18 at 00:02:58
 
I also did a similar test to a Dyna muffler (catalyst version).  It registered 27.5” H2O.  Sorry, I don’t have a non-cat version but I’ve heard they flow about the same.

[img][/img]
Back to top
 

IMG_02641.JPG

Knowledge is power.
  IP Logged
DragBikeMike
Serious Thumper
*****
Offline

SuzukiSavage.com
Rocks!

Posts: 4071
Honolulu
Re: Stock Muffler Eval & Upgrade
Reply #4 - 05/16/18 at 00:04:27
 
I reinstalled the muffler and cut it open using a 2-1/2” diameter hole saw.  This required that I make a plug to go in the tailpipe so that the hole saw stayed on center.  I learned that the plug must be a drive fit.  A push fit allows the plug to back out of the hole and the saw to run away.  I nicked my chrome a bit.  I did the saw cut with the muffler installed since it held everything nice & steady.  

[img][/img]
Back to top
 

IMG_02631.JPG

Knowledge is power.
  IP Logged
DragBikeMike
Serious Thumper
*****
Offline

SuzukiSavage.com
Rocks!

Posts: 4071
Honolulu
Re: Stock Muffler Eval & Upgrade
Reply #5 - 05/16/18 at 00:07:50
 
I noted one post in this forum where the member simply drove a wooden dowel into the tailpipe and drilled/sawed away.

Here’s what came out.

[img][/img]
Back to top
 

IMG_02541.JPG

Knowledge is power.
  IP Logged
DragBikeMike
Serious Thumper
*****
Offline

SuzukiSavage.com
Rocks!

Posts: 4071
Honolulu
Re: Stock Muffler Eval & Upgrade
Reply #6 - 05/16/18 at 00:09:10
 
Here’s what I saw inside  from the rear.

[img][/img]
Back to top
 

IMG_02561.JPG

Knowledge is power.
  IP Logged
DragBikeMike
Serious Thumper
*****
Offline

SuzukiSavage.com
Rocks!

Posts: 4071
Honolulu
Re: Stock Muffler Eval & Upgrade
Reply #7 - 05/16/18 at 00:11:04
 
I removed the muffler and did a thorough visual & dimensional inspection.  Here’s a detailed sketch of the interior.

[img][/img]
Back to top
 

Muffler_Dimensions_2_0001.jpg

Knowledge is power.
  IP Logged
DragBikeMike
Serious Thumper
*****
Offline

SuzukiSavage.com
Rocks!

Posts: 4071
Honolulu
Re: Stock Muffler Eval & Upgrade
Reply #8 - 05/16/18 at 00:14:31
 
There are three chambers (X, Y & Z) separated by solid plates (B, C & D).  Small ¾” diameter tubes transfer the hot gasses between the chambers.  There are two perforated plates (like really perforated, kinda like a screen they’re so perforated) that appear to be used to diffuse the hot gasses as they pass across the plate.  I labeled the perforated plates (A & D).  Be aware that there are two details missing from the sketch.  There is some sort of diverter/deflector contraption just forward of the attenuation tube.  It appears to be intended to help channel the hot gasses into the tube as they change direction from moving forward to moving toward the rear.  There are also two holes about 5/16” diameter, one in solid plate “B” and one in solid plate “”C”.  These small holes are on the periphery of the solid plates.  They effectively short circuit the plate, but they are very small so it is probably a very whimpy short circuit.

I immediately noticed that the actual muffler did not agree with the sketches provided in the post for Hartman Mod.  The sketches had some features that were sort of like what I was holding in my hands, but they really weren’t close to the actual design.  Based on what I could see, it looked like I might be able to make some significant improvements without increasing the noise level too much.

Here is the flow path.

[img][/img]
Back to top
 

Muffler_Flow.jpg

Knowledge is power.
  IP Logged
DragBikeMike
Serious Thumper
*****
Offline

SuzukiSavage.com
Rocks!

Posts: 4071
Honolulu
Re: Stock Muffler Eval & Upgrade
Reply #9 - 05/16/18 at 00:18:36
 
Hot gasses enter the muffler at chamber “X” where they pass through perforated plate “A”, collide with solid plate “B” and make the first direction change.  Then they enter transit tube 1 and move aft to chamber “Z”.  Once in chamber “Z” they pass through perforated plate “D”, collide with solid plate “E” and make the second direction change.  The gasses then move back forward and again pass through perforated plate “D” and into transit tube 2.  They continue moving forward through the transit tube and enter chamber “Y”.  In chamber “Y” the gasses collide with the backside of solid plate “B” and make the third direction change.  The gasses then head aft again and enter the attenuation tube.  This tube has a perforated section surrounded by a chamber.  I call it the attenuation chamber.  The acoustic energy diffuses through the perforations and enters the chamber where I assume it gets attenuated.  The hot gasses continue aft and out the muffler to the atmosphere.  No wonder its quiet.

I believe that each time the hot gasses pass through a perforated plate, collide with an immovable object, change direction, squeeze through a tube, or disburse through an attenuation device, acoustic energy is diminished.  If my guess is correct, the key to better flow without excessive noise is to provide a less restrictive path while maintaining the collisions, turns, squeezing, disbursement and attenuation.

The low hanging fruit here is the attenuation tube.  It’s relatively easy to remove.  Its relatively easy to replace with a larger tube.  Its relatively easy to reverse course and restore to stock if the mod doesn’t work as intended.  Unfortunately, it’s at the very end of the flow path.  If I want to capitalize on the volume of the muffler, I probably should be making improvements at the beginning of the flow path (transit tube 1).  But until I have a better idea as to what effects various alterations will have on noise, I figured I should stick to stuff that is easily reversed
Back to top
 
 

Knowledge is power.
  IP Logged
DragBikeMike
Serious Thumper
*****
Offline

SuzukiSavage.com
Rocks!

Posts: 4071
Honolulu
Re: Stock Muffler Eval & Upgrade
Reply #10 - 05/16/18 at 00:22:48
 
I tested the muffler with the entire attenuation tube removed.  The restriction was reduced significantly.  Now the poor man’s flow bench registered 26.5” H2O (1” less than Dyna).  So how loud is it.  I reinstalled the muffler and ran it.  Whoa!  Yuk!  Waaaaaay too loud.
Back to top
 
 

Knowledge is power.
  IP Logged
DragBikeMike
Serious Thumper
*****
Offline

SuzukiSavage.com
Rocks!

Posts: 4071
Honolulu
Re: Stock Muffler Eval & Upgrade
Reply #11 - 05/16/18 at 00:27:06
 
I scrounged up some materials to fabricate a new attenuator tube with a larger inside diameter.  One-inch electrical conduit looked like it would fit the bill.  It has an inside diameter of 1-1/16” and an outside diameter of 1-3/16”.  A ten foot section is about $11 (sorry, they don’t sell short sections).  The stock attenuation chamber has an outside diameter of 1-1/2”,  so now I needed some material with 1-1/2” outside diameter.  I could find it on the internet from all sorts of mail order outfits like Summit, J.C. Whitney, Advanced Auto, etc.  But I couldn’t find any locally.  What I did find was a Moen handicap hand rail for a shower stall.  Its stainless steel, exactly the right outside diameter, and very thin wall (which will allow lots of room between the inner &  outer components of the chamber).  It was like $20.  What the heck, I’m on a mission.  I bet you guys and gals on the mainland could scrounge this stuff up for a fraction of what I paid.

I have plenty of old aluminum stock laying around from previous projects so I started by making a new end cap with a 1-1/16” hole (same as the conduit ID).  Tried it with just the end cap.  Better, but still way too loud.   Flow test with just the new end cap pulled 28” H2O
Back to top
 
 

Knowledge is power.
  IP Logged
DragBikeMike
Serious Thumper
*****
Offline

SuzukiSavage.com
Rocks!

Posts: 4071
Honolulu
Re: Stock Muffler Eval & Upgrade
Reply #12 - 05/16/18 at 00:41:44
 
Then I cut off a 7-3/32” section of the conduit and counterbored the end cap to provide a nice fit.  So now when I installed the end cap the conduit ran from the end cap all the way to solid plate “C”.  It would be pretty close to the stock flow path.  I ran it again.  Better, but still too loud for me.  Some of you might find this configuration to your liking, but it’s too loud for me.  Flow test in this configuration pulled 31” H2O.  The restriction was higher because now the flow bench had to pull the air all the way through the stock flow path and the existing hole in solid plate “C” was only a little over ¾” diameter.

Here's a sketch of that configuration.

[img][/img]
Back to top
 

Solid_Tube_Flow.jpg

Knowledge is power.
  IP Logged
DragBikeMike
Serious Thumper
*****
Offline

SuzukiSavage.com
Rocks!

Posts: 4071
Honolulu
Re: Stock Muffler Eval & Upgrade
Reply #13 - 05/16/18 at 00:45:36
 
So now it’s the moment of truth.  Do I hog out solid plate “C” to 1-3/16” so that the conduit can pass through to chamber “Y”.  I can still restore to stock configuration by simply fabricating a bushing to slip over the stock attenuator tube.  Go for broke.  I used a step drill to enlarge the hole in plate “C” to 1-3/16”.  Now its setup for a new, larger attenuator tube assembly.

Here is a pic of the step drill.  Using a Ryobi cordless worked nice because I could adjust the clutch so that it didn’t rip the plate up if the bit snagged.  It made a beautiful hole.

[img][/img]
Back to top
 

IMG_02741.JPG

Knowledge is power.
  IP Logged
DragBikeMike
Serious Thumper
*****
Offline

SuzukiSavage.com
Rocks!

Posts: 4071
Honolulu
Re: Stock Muffler Eval & Upgrade
Reply #14 - 05/16/18 at 00:46:36
 
Here is a pic of the new 1-3/16” hole.

[img][/img]
Back to top
 

IMG_02691.JPG

Knowledge is power.
  IP Logged
Pages: 1 2 3 4
Send Topic Print


« Home

 
« Home
SuzukiSavage.com
03/29/24 at 02:03:35



General CategoryRubber Side Down! › Stock Muffler Eval & Upgrade


SuzukiSavage.com » Powered by YaBB 2.2!
YaBB © 2000-2007. All Rights Reserved.