Re: [MBZ] OT: Muffler design?
BTW both Polaris and OMC made rotary snowmobiles also. Polaris used the same 303 and the nearly mythical 606 dual rotor. OMC I think manufactured their own engines and sold them under the Johnson line. OMC also sold Evinrude sleds but I don't think those got the rotary. The 303 made something like 19hp, its replacement the 295 was something like 24hp. The OMC sleds had the option of either a 35 or 45hp (they didn't list sizes) engine but the sleds were big heavy monsters... -Curt Date: Mon, 18 Jan 2010 23:40:43 -0600 From: Fmiser To: Mercedes Discussion List Subject: Re: [MBZ] OT: Muffler design? Message-ID: <20100118234043.5f56accb.fmi...@gmail.com> Content-Type: text/plain; charset=US-ASCII > Curt Raymond wrote: > 2 stroke Wankle... > > Well a Wankle engine with 40:1 premix (no sump) anyway... > > http://www.deadsledwrenchers.net/arcticcat/wanklepanther2.jpg Hmm. Not a very good picture For better pictures, see: http://sledaction.homestead.com/Panther303_2.html No affiliation, I just went googling when you wrote there was a wankle snowmobile. -- Philip ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] OT: Muffler design?
Too right... The first link is mine though. Need to get some video of it, the sound it makes is remarkable. -Curt Date: Mon, 18 Jan 2010 23:40:43 -0600 From: Fmiser To: Mercedes Discussion List Subject: Re: [MBZ] OT: Muffler design? Message-ID: <20100118234043.5f56accb.fmi...@gmail.com> Content-Type: text/plain; charset=US-ASCII > Curt Raymond wrote: > 2 stroke Wankle... > > Well a Wankle engine with 40:1 premix (no sump) anyway... > > http://www.deadsledwrenchers.net/arcticcat/wanklepanther2.jpg Hmm. Not a very good picture For better pictures, see: http://sledaction.homestead.com/Panther303_2.html No affiliation, I just went googling when you wrote there was a wankle snowmobile. -- Philip ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] OT: Muffler design?
> Curt Raymond wrote: > 2 stroke Wankle... > > Well a Wankle engine with 40:1 premix (no sump) anyway... > > http://www.deadsledwrenchers.net/arcticcat/wanklepanther2.jpg Hmm. Not a very good picture For better pictures, see: http://sledaction.homestead.com/Panther303_2.html No affiliation, I just went googling when you wrote there was a wankle snowmobile. -- Philip ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] OT: Muffler design?
2 stroke Wankle... Well a Wankle engine with 40:1 premix (no sump) anyway... http://www.deadsledwrenchers.net/arcticcat/wanklepanther2.jpg -Curt Date: Mon, 18 Jan 2010 21:13:15 -0500 From: Mitch Haley To: Mercedes Discussion List Subject: Re: [MBZ] OT: Muffler design? Message-ID: <4b55153b.1040...@voyager.net> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Jim Cathey wrote: > This is a 2-stroke, not a diesel right? Where's the oxygen > to come from? Four stroke wankel, but still not much O2 coming out of it. Mitch. ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] OT: Muffler design?
Jim Cathey wrote: This is a 2-stroke, not a diesel right? Where's the oxygen to come from? Four stroke wankel, but still not much O2 coming out of it. Mitch. ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] OT: Muffler design?
I don't think I would use steel wool. It burns. Try it. Even soaking wet, it will ignite and burn. This is a 2-stroke, not a diesel right? Where's the oxygen to come from? -- Jim ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] OT: Muffler design?
Yeah I've been thinking about how to do that... Dirtbike mufflers have an end cap thats held on with screws. I've just started to come up with a plan for how to do that... Honestly I'm pretty sure its not going to be that big a problem. If I do a reasonably good job baffling the filling is mostly for show. -Curt Date: Mon, 18 Jan 2010 15:38:23 -0600 From: "R A Bennell" To: "Mercedes Discussion List" Subject: Re: [MBZ] OT: Muffler design? Message-ID: Content-Type: text/plain; charset="iso-8859-1" If you do make a muffler, let me suggest that you make it so it can be opened up to check and maybe replace the insulation periodically. Randy -Original Message- From: mercedes-boun...@okiebenz.com [mailto:mercedes-boun...@okiebenz.com]on Behalf Of Curt Raymond Sent: Monday, January 18, 2010 2:49 PM To: Diesel List Subject: Re: [MBZ] OT: Muffler design? It sure does doesn't it. Can't believe I'd forgotten that. Fiberglass it is then. -Curt ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] OT: Muffler design?
If you do make a muffler, let me suggest that you make it so it can be opened up to check and maybe replace the insulation periodically. Randy -Original Message- From: mercedes-boun...@okiebenz.com [mailto:mercedes-boun...@okiebenz.com]on Behalf Of Curt Raymond Sent: Monday, January 18, 2010 2:49 PM To: Diesel List Subject: Re: [MBZ] OT: Muffler design? It sure does doesn't it. Can't believe I'd forgotten that. Fiberglass it is then. -Curt Date: Mon, 18 Jan 2010 13:34:20 -0600 From: "R A Bennell" To: "Mercedes Discussion List" Subject: Re: [MBZ] OT: Muffler design? Message-ID: Content-Type: text/plain; charset="iso-8859-1" I don't think I would use steel wool. It burns. Try it. Even soaking wet, it will ignite and burn. Randy ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] OT: Muffler design?
There is a "new" sort of insulation in the stores around here sold under the name Roxol if I recall correctly. It is supposedly fire proof. Looks sort of like basic fiberlass batts but is sort of greeny gray color and a bit of a different texture. Randy -Original Message- From: mercedes-boun...@okiebenz.com [mailto:mercedes-boun...@okiebenz.com]on Behalf Of Curt Raymond Sent: Monday, January 18, 2010 2:49 PM To: Diesel List Subject: Re: [MBZ] OT: Muffler design? It sure does doesn't it. Can't believe I'd forgotten that. Fiberglass it is then. -Curt Date: Mon, 18 Jan 2010 13:34:20 -0600 From: "R A Bennell" To: "Mercedes Discussion List" Subject: Re: [MBZ] OT: Muffler design? Message-ID: Content-Type: text/plain; charset="iso-8859-1" I don't think I would use steel wool. It burns. Try it. Even soaking wet, it will ignite and burn. Randy ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] OT: Muffler design?
It sure does doesn't it. Can't believe I'd forgotten that. Fiberglass it is then. -Curt Date: Mon, 18 Jan 2010 13:34:20 -0600 From: "R A Bennell" To: "Mercedes Discussion List" Subject: Re: [MBZ] OT: Muffler design? Message-ID: Content-Type: text/plain; charset="iso-8859-1" I don't think I would use steel wool. It burns. Try it. Even soaking wet, it will ignite and burn. Randy ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] OT: Muffler design?
I wonder what sort of muffler the Mazda Rotary cars had? I know I have read that the rotary is a real noise maker when unmuffled. I think there was an article about someone running a rotary on the salt without any muffler and the comments about the amount of noise it made. Randy -Original Message- From: mercedes-boun...@okiebenz.com [mailto:mercedes-boun...@okiebenz.com]on Behalf Of Barry Stark Sent: Monday, January 18, 2010 2:13 PM To: 'Mercedes Discussion List' Subject: Re: [MBZ] OT: Muffler design? Randy - Hey, I did say it would burn out over time. Actually when I have seen that used in the past, it was the real coarse stuff not the hair fine stuff. The fine stuff doesnt work as well as the coarse stiff anyway as it just seems to block the exhaust flow where the coarse stuff lets the sound get trapped in it and bounce around thereby robbing the sound pulse of its' energy. Also the silencer with the steel wool located was at the end of the "stinger" on the expansion chamber. The temperature at that point is quite a bit lower than the "fire" coming out of the exhaust port. Curt - In your situation, I'm guessing that the muffler may be rather close to the exhaust port. The steel, even the coarse stuff may heat up and oxidize rather quickly. I was thinking that maybe you could find a machine shop that is turning some stainless parts on a lathe and retrieve some of those "pigtail" turnings. They may be heavy enough not to heat up as much as fine strand and they would not oxidize as readily as a steel part. Even fiberglass close to the exhaust port would not last long. I imagine that rotary engines have a pretty hot exhaust stream much like a 2 stroke. On a 4 stroke, the exhaust valve ends up taking some of the heat from the exhaust stream and transferring it to the head, so things are a bit cooler. Barry > -Original Message- > From: mercedes-boun...@okiebenz.com [mailto:mercedes- > boun...@okiebenz.com] On Behalf Of R A Bennell > Sent: Monday, January 18, 2010 11:34 AM > To: Mercedes Discussion List > Subject: Re: [MBZ] OT: Muffler design? > > I don't think I would use steel wool. It burns. Try it. Even soaking > wet, it will ignite and burn. > > Randy > > -Original Message- > From: mercedes-boun...@okiebenz.com > [mailto:mercedes-boun...@okiebenz.com]on Behalf Of Curt Raymond > Sent: Monday, January 18, 2010 11:27 AM > To: Diesel List > Subject: Re: [MBZ] OT: Muffler design? > > > Barry, > > Great info! I knew a little of that but you put it into context. > > My problem is that this is such an oddball machine. '71 Arctic Cat > Panther 303 Rotary... They used the 303 from > '69 through around '72. This was the dawn of race sleds and the 303 was > NOT one of those ;) > > Theres extremely limited space to put the pipe in and any performance > tuning has already been ruined because the > exhaust port faces almost straight down. Theres a pipe from it around > to the front (maybe 12") which then takes a > left turn (the engine is about the same diameter as a 5 gallon bucket > but only about 2/3 as tall. If it were a > bucket it'd be lying on its side in the sled) and enters the "muffler" > which is about the size and shape of a > coffee can in the center of one end of the can. At the other end of the > can another pipe comes out making another > left turn. It goes down about 16" and makes a turn stright down and > out. > > So as you can see this is about the WORST design possible... On a > positive note I don't think a rotary engine > requires much exhaust gas scavenging since the intake and exhaust ports > don't overlap like they do in a piston > engine... > > I like the steel wool idea, I think I'm going to try to end up with a > combo approach, baffles and steel wool... > > -Curt > > Date: Mon, 18 Jan 2010 08:38:04 -0800 > From: "Barry Stark" > To: "'Mercedes Discussion List'" > Subject: Re: [MBZ] OT: Muffler design? > Message-ID: <01ca985c$9c10f290$d432d7...@net> > Content-Type: text/plain; charset=us-ascii > > Curt - > Manfred is correct. The downside of not using a properly designed > exhaust > system is that you may end up with a destructively lean mixture at full > throttle, or you may just have reduced power. While the reduced power > is > likely not a big thing, the excessively lean condition can be. With > whatever > system you end up with be sure to take a spark plug reading after a > short > full power run to determine if the mixture is within range. If it is > just a > bit lean you can likely either adjust the high speed needle valve or > install > a bigger main jet depending on the design of
Re: [MBZ] OT: Muffler design?
Randy - Hey, I did say it would burn out over time. Actually when I have seen that used in the past, it was the real coarse stuff not the hair fine stuff. The fine stuff doesnt work as well as the coarse stiff anyway as it just seems to block the exhaust flow where the coarse stuff lets the sound get trapped in it and bounce around thereby robbing the sound pulse of its' energy. Also the silencer with the steel wool located was at the end of the "stinger" on the expansion chamber. The temperature at that point is quite a bit lower than the "fire" coming out of the exhaust port. Curt - In your situation, I'm guessing that the muffler may be rather close to the exhaust port. The steel, even the coarse stuff may heat up and oxidize rather quickly. I was thinking that maybe you could find a machine shop that is turning some stainless parts on a lathe and retrieve some of those "pigtail" turnings. They may be heavy enough not to heat up as much as fine strand and they would not oxidize as readily as a steel part. Even fiberglass close to the exhaust port would not last long. I imagine that rotary engines have a pretty hot exhaust stream much like a 2 stroke. On a 4 stroke, the exhaust valve ends up taking some of the heat from the exhaust stream and transferring it to the head, so things are a bit cooler. Barry > -Original Message- > From: mercedes-boun...@okiebenz.com [mailto:mercedes- > boun...@okiebenz.com] On Behalf Of R A Bennell > Sent: Monday, January 18, 2010 11:34 AM > To: Mercedes Discussion List > Subject: Re: [MBZ] OT: Muffler design? > > I don't think I would use steel wool. It burns. Try it. Even soaking > wet, it will ignite and burn. > > Randy > > -Original Message- > From: mercedes-boun...@okiebenz.com > [mailto:mercedes-boun...@okiebenz.com]on Behalf Of Curt Raymond > Sent: Monday, January 18, 2010 11:27 AM > To: Diesel List > Subject: Re: [MBZ] OT: Muffler design? > > > Barry, > > Great info! I knew a little of that but you put it into context. > > My problem is that this is such an oddball machine. '71 Arctic Cat > Panther 303 Rotary... They used the 303 from > '69 through around '72. This was the dawn of race sleds and the 303 was > NOT one of those ;) > > Theres extremely limited space to put the pipe in and any performance > tuning has already been ruined because the > exhaust port faces almost straight down. Theres a pipe from it around > to the front (maybe 12") which then takes a > left turn (the engine is about the same diameter as a 5 gallon bucket > but only about 2/3 as tall. If it were a > bucket it'd be lying on its side in the sled) and enters the "muffler" > which is about the size and shape of a > coffee can in the center of one end of the can. At the other end of the > can another pipe comes out making another > left turn. It goes down about 16" and makes a turn stright down and > out. > > So as you can see this is about the WORST design possible... On a > positive note I don't think a rotary engine > requires much exhaust gas scavenging since the intake and exhaust ports > don't overlap like they do in a piston > engine... > > I like the steel wool idea, I think I'm going to try to end up with a > combo approach, baffles and steel wool... > > -Curt > > Date: Mon, 18 Jan 2010 08:38:04 -0800 > From: "Barry Stark" > To: "'Mercedes Discussion List'" > Subject: Re: [MBZ] OT: Muffler design? > Message-ID: <01ca985c$9c10f290$d432d7...@net> > Content-Type: text/plain; charset=us-ascii > > Curt - > Manfred is correct. The downside of not using a properly designed > exhaust > system is that you may end up with a destructively lean mixture at full > throttle, or you may just have reduced power. While the reduced power > is > likely not a big thing, the excessively lean condition can be. With > whatever > system you end up with be sure to take a spark plug reading after a > short > full power run to determine if the mixture is within range. If it is > just a > bit lean you can likely either adjust the high speed needle valve or > install > a bigger main jet depending on the design of the carburetor. If it > "blubbers" it may be too rich and the appropriate adjustments can be > performed to correct that instance as well. The best system for a 2 > stroke > is what is called an expansion chamber. It consists of a divergent > pipe, > like a megaphone, and then a convergent pipe, just the opposite, > followed by > a small length of a small dia. straight pipe. The length and diameters > of > each of these sections are somewhat critical but the cones can
Re: [MBZ] OT: Muffler design?
I don't think I would use steel wool. It burns. Try it. Even soaking wet, it will ignite and burn. Randy -Original Message- From: mercedes-boun...@okiebenz.com [mailto:mercedes-boun...@okiebenz.com]on Behalf Of Curt Raymond Sent: Monday, January 18, 2010 11:27 AM To: Diesel List Subject: Re: [MBZ] OT: Muffler design? Barry, Great info! I knew a little of that but you put it into context. My problem is that this is such an oddball machine. '71 Arctic Cat Panther 303 Rotary... They used the 303 from '69 through around '72. This was the dawn of race sleds and the 303 was NOT one of those ;) Theres extremely limited space to put the pipe in and any performance tuning has already been ruined because the exhaust port faces almost straight down. Theres a pipe from it around to the front (maybe 12") which then takes a left turn (the engine is about the same diameter as a 5 gallon bucket but only about 2/3 as tall. If it were a bucket it'd be lying on its side in the sled) and enters the "muffler" which is about the size and shape of a coffee can in the center of one end of the can. At the other end of the can another pipe comes out making another left turn. It goes down about 16" and makes a turn stright down and out. So as you can see this is about the WORST design possible... On a positive note I don't think a rotary engine requires much exhaust gas scavenging since the intake and exhaust ports don't overlap like they do in a piston engine... I like the steel wool idea, I think I'm going to try to end up with a combo approach, baffles and steel wool... -Curt Date: Mon, 18 Jan 2010 08:38:04 -0800 From: "Barry Stark" To: "'Mercedes Discussion List'" Subject: Re: [MBZ] OT: Muffler design? Message-ID: <01ca985c$9c10f290$d432d7...@net> Content-Type: text/plain; charset=us-ascii Curt - Manfred is correct. The downside of not using a properly designed exhaust system is that you may end up with a destructively lean mixture at full throttle, or you may just have reduced power. While the reduced power is likely not a big thing, the excessively lean condition can be. With whatever system you end up with be sure to take a spark plug reading after a short full power run to determine if the mixture is within range. If it is just a bit lean you can likely either adjust the high speed needle valve or install a bigger main jet depending on the design of the carburetor. If it "blubbers" it may be too rich and the appropriate adjustments can be performed to correct that instance as well. The best system for a 2 stroke is what is called an expansion chamber. It consists of a divergent pipe, like a megaphone, and then a convergent pipe, just the opposite, followed by a small length of a small dia. straight pipe. The length and diameters of each of these sections are somewhat critical but the cones can be ovaled a bit and pipes curved usually without too much loss of efficiency. The unfortunate part of these expansion chambers if they can be quite noisy. If you have ever witnessed a 2 stroke racing motorcycle you will know what I mean. The factory muffler is likely designed to try and emulate the characteristics of the expansion chamber in a very small package. Very hard to do without some fluid flow type engineers and a dynamometer. Your best bet may just be to try and make a unit that is quiet as possible, take plug reading and adjust the mixture, and live with any power loss. The secret to making a quiet muffler is to rob the sound energy from the exhaust pulse. This is done by trying to bounce the sound off as many surfaces as possible. Often a "gun" type silencer will do pretty well which is basically a pipe. With a bunch of holes drilled in it, surrounded by a chamber stuffed with sound deadening material like steel wool or rolled fiberglass. If you use this design the deadening material will burn out over time and will need to be replenished. A more longer life method may be a series of chambers with internal baffles that have holes with the edges deformed like a simple cheese grater. You may have seen this used in automotive mufflers. By the way, have you looked to see if there is a performance aftermarket exhaust system for your machine? There may one available that is not too noisy. Ebay? If you would like to learn more about 2 stroke expansion chambers and their theory I just Googled "two stroke cycle expansion chamber design" and got a number of interesting hits including some possible chamber design parameter computer programs. Wikipedia had an excellent animated discussion on how expansion chambers work. http://en.wikipedia.org/wiki/Expansion_chamber I hope some of this helps out. Barry ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okie
Re: [MBZ] OT: Muffler design?
Barry, Great info! I knew a little of that but you put it into context. My problem is that this is such an oddball machine. '71 Arctic Cat Panther 303 Rotary... They used the 303 from '69 through around '72. This was the dawn of race sleds and the 303 was NOT one of those ;) Theres extremely limited space to put the pipe in and any performance tuning has already been ruined because the exhaust port faces almost straight down. Theres a pipe from it around to the front (maybe 12") which then takes a left turn (the engine is about the same diameter as a 5 gallon bucket but only about 2/3 as tall. If it were a bucket it'd be lying on its side in the sled) and enters the "muffler" which is about the size and shape of a coffee can in the center of one end of the can. At the other end of the can another pipe comes out making another left turn. It goes down about 16" and makes a turn stright down and out. So as you can see this is about the WORST design possible... On a positive note I don't think a rotary engine requires much exhaust gas scavenging since the intake and exhaust ports don't overlap like they do in a piston engine... I like the steel wool idea, I think I'm going to try to end up with a combo approach, baffles and steel wool... -Curt Date: Mon, 18 Jan 2010 08:38:04 -0800 From: "Barry Stark" To: "'Mercedes Discussion List'" Subject: Re: [MBZ] OT: Muffler design? Message-ID: <01ca985c$9c10f290$d432d7...@net> Content-Type: text/plain; charset=us-ascii Curt - Manfred is correct. The downside of not using a properly designed exhaust system is that you may end up with a destructively lean mixture at full throttle, or you may just have reduced power. While the reduced power is likely not a big thing, the excessively lean condition can be. With whatever system you end up with be sure to take a spark plug reading after a short full power run to determine if the mixture is within range. If it is just a bit lean you can likely either adjust the high speed needle valve or install a bigger main jet depending on the design of the carburetor. If it "blubbers" it may be too rich and the appropriate adjustments can be performed to correct that instance as well. The best system for a 2 stroke is what is called an expansion chamber. It consists of a divergent pipe, like a megaphone, and then a convergent pipe, just the opposite, followed by a small length of a small dia. straight pipe. The length and diameters of each of these sections are somewhat critical but the cones can be ovaled a bit and pipes curved usually without too much loss of efficiency. The unfortunate part of these expansion chambers if they can be quite noisy. If you have ever witnessed a 2 stroke racing motorcycle you will know what I mean. The factory muffler is likely designed to try and emulate the characteristics of the expansion chamber in a very small package. Very hard to do without some fluid flow type engineers and a dynamometer. Your best bet may just be to try and make a unit that is quiet as possible, take plug reading and adjust the mixture, and live with any power loss. The secret to making a quiet muffler is to rob the sound energy from the exhaust pulse. This is done by trying to bounce the sound off as many surfaces as possible. Often a "gun" type silencer will do pretty well which is basically a pipe. With a bunch of holes drilled in it, surrounded by a chamber stuffed with sound deadening material like steel wool or rolled fiberglass. If you use this design the deadening material will burn out over time and will need to be replenished. A more longer life method may be a series of chambers with internal baffles that have holes with the edges deformed like a simple cheese grater. You may have seen this used in automotive mufflers. By the way, have you looked to see if there is a performance aftermarket exhaust system for your machine? There may one available that is not too noisy. Ebay? If you would like to learn more about 2 stroke expansion chambers and their theory I just Googled "two stroke cycle expansion chamber design" and got a number of interesting hits including some possible chamber design parameter computer programs. Wikipedia had an excellent animated discussion on how expansion chambers work. http://en.wikipedia.org/wiki/Expansion_chamber I hope some of this helps out. Barry ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] OT: Muffler design?
Thats true today but back in '71 on a utility machine like this Arctic Cat was looking for some measure of quiet, not performance. This engine is weird too as its a rotary... AFAIK none of the snowmobile makers ever did a tuned pipe with a rotary. So anyway I'm also not really concerned about performance. This is the sled I use to haul wood, it'll never get over 50mph, I just need it quiet enough to not piss off the wife. I like the idea of cutting the old one apart, I'll give that a shot. -Curt Date: Mon, 18 Jan 2010 09:43:36 -0500 From: MG To: Mercedes Discussion List Subject: Re: [MBZ] OT: Muffler design? Message-ID: <4b547398.3070...@yahoo.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Curt I think the design of mufflers is a bit different between two and four stroke. The two stroke muffler is usually an integral part of the power band tuning of the motor, much more so than with a four stroke. Try cutting open the original muffler and see if any of the pipe and baffling are still in there to see if you might be able to copy it in the new muffler. The closer you can get to the original the better. Even the distance between the head and the muffler is part of the tuning. Manfred Date: Sun, 17 Jan 2010 19:37:07 -0800 (PST) From: Curt Raymond Anybody know anything about muffler design? I've got an old snowmobile that the muffler is NLA and a strange enough design that nothing else will work right. I bought a muffler from a Cub Cadet tractor and its okay but still too loud. It looks like that "muffler" is just a can with a tube that has holes punched all around it inside. I *think* quiet mufflers generally have some kind of fiberglass packing inside. I've got to cut this muffler anyway since its too long, I was thinking that since I had to have it open I'd stuff some fiberglass in (either the pink stuff or some mat) around the outside and see if that helped any. I don't think it could make it any worse... I've also thought about welding in more baffles but theres not that much space, its about the size of a coffee can. -Curt ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] OT: Muffler design?
Curt - Manfred is correct. The downside of not using a properly designed exhaust system is that you may end up with a destructively lean mixture at full throttle, or you may just have reduced power. While the reduced power is likely not a big thing, the excessively lean condition can be. With whatever system you end up with be sure to take a spark plug reading after a short full power run to determine if the mixture is within range. If it is just a bit lean you can likely either adjust the high speed needle valve or install a bigger main jet depending on the design of the carburetor. If it "blubbers" it may be too rich and the appropriate adjustments can be performed to correct that instance as well. The best system for a 2 stroke is what is called an expansion chamber. It consists of a divergent pipe, like a megaphone, and then a convergent pipe, just the opposite, followed by a small length of a small dia. straight pipe. The length and diameters of each of these sections are somewhat critical but the cones can be ovaled a bit and pipes curved usually without too much loss of efficiency. The unfortunate part of these expansion chambers if they can be quite noisy. If you have ever witnessed a 2 stroke racing motorcycle you will know what I mean. The factory muffler is likely designed to try and emulate the characteristics of the expansion chamber in a very small package. Very hard to do without some fluid flow type engineers and a dynamometer. Your best bet may just be to try and make a unit that is quiet as possible, take plug reading and adjust the mixture, and live with any power loss. The secret to making a quiet muffler is to rob the sound energy from the exhaust pulse. This is done by trying to bounce the sound off as many surfaces as possible. Often a "gun" type silencer will do pretty well which is basically a pipe. With a bunch of holes drilled in it, surrounded by a chamber stuffed with sound deadening material like steel wool or rolled fiberglass. If you use this design the deadening material will burn out over time and will need to be replenished. A more longer life method may be a series of chambers with internal baffles that have holes with the edges deformed like a simple cheese grater. You may have seen this used in automotive mufflers. By the way, have you looked to see if there is a performance aftermarket exhaust system for your machine? There may one available that is not too noisy. Ebay? If you would like to learn more about 2 stroke expansion chambers and their theory I just Googled "two stroke cycle expansion chamber design" and got a number of interesting hits including some possible chamber design parameter computer programs. Wikipedia had an excellent animated discussion on how expansion chambers work. http://en.wikipedia.org/wiki/Expansion_chamber I hope some of this helps out. Barry > > -Original Message- > > From: mercedes-boun...@okiebenz.com > > [mailto:mercedes-boun...@okiebenz.com]on Behalf Of MG > > Sent: Monday, January 18, 2010 6:44 AM > > To: Mercedes Discussion List > > Subject: Re: [MBZ] OT: Muffler design? > > > > > > Curt I think the design of mufflers is a bit different between > > two and four stroke. The two stroke muffler is usually an > > integral part of the power band tuning of the motor, much more so > > than with a four stroke. Try cutting open the original muffler > > and see if any of the pipe and baffling are still in there to see > > if you might be able to copy it in the new muffler. The closer > > you can get to the original the better. Even the distance between > > the head and the muffler is part of the tuning. > > > > Manfred > > > > > > > > Date: Sun, 17 Jan 2010 19:37:07 -0800 (PST) > > From: Curt Raymond > > > > Anybody know anything about muffler design? I've got an old > > snowmobile that the muffler is NLA and a strange enough design > > that nothing else will work right. > > I bought a muffler from a Cub Cadet tractor and its okay but > > still too loud. It looks like that "muffler" is just a can with a > > tube that has holes punched all around it inside. > > > > I *think* quiet mufflers generally have some kind of fiberglass > > packing inside. I've got to cut this muffler anyway since its too > > long, I was thinking that since I had to have it open I'd stuff > > some fiberglass in (either the pink stuff or some mat) around the > > outside and see if that helped any. I don't think it could make > > it any worse... > > > > I've also thought about welding in more baffles but theres not > > that much space, its about the size of a coffee can. > > > > -Curt > > > > __
Re: [MBZ] OT: Muffler design?
Curt I think the design of mufflers is a bit different between two and four stroke. The two stroke muffler is usually an integral part of the power band tuning of the motor, much more so than with a four stroke. Try cutting open the original muffler and see if any of the pipe and baffling are still in there to see if you might be able to copy it in the new muffler. The closer you can get to the original the better. Even the distance between the head and the muffler is part of the tuning. Manfred Date: Sun, 17 Jan 2010 19:37:07 -0800 (PST) From: Curt Raymond Anybody know anything about muffler design? I've got an old snowmobile that the muffler is NLA and a strange enough design that nothing else will work right. I bought a muffler from a Cub Cadet tractor and its okay but still too loud. It looks like that "muffler" is just a can with a tube that has holes punched all around it inside. I *think* quiet mufflers generally have some kind of fiberglass packing inside. I've got to cut this muffler anyway since its too long, I was thinking that since I had to have it open I'd stuff some fiberglass in (either the pink stuff or some mat) around the outside and see if that helped any. I don't think it could make it any worse... I've also thought about welding in more baffles but theres not that much space, its about the size of a coffee can. -Curt ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
