Muffler, any down side?

[Smac61]

I'm just about ready to order a "Walkerized" muffler for my Husky 350.
Although I'm happy with its stock performance, why not let it run cooler, stronger and increase the longevity in the process.
Warranty issues aside, are there any downsides to doing this?
From what I've read no, but I'm a newbie...

For those of you that have done this, whats required after the new muffler goes on?
I presume lowspeed, high speed and idle adjustments. anything else?

Thanks,
Sean

 

[Ryan Willock]

there is no down side that i know of but like you i haven't been modifing for very long. im getting ready to order a walkerized muffler for my ms460. i opened up my 036 and my dad's 021 and noticed a huge differance! well worth it IMHO:angel:

 

[eyolf]

Many people assume that a 2-stroke engine is "dirty"...a pollution machine...because it uses oil in the gas to lube.

Not a very accurate assumption. Some of the oil burns, but forms particulates, like a diesel. Not a big problem as the unburned HC (unburned gas) that escapes from the muffler very stroke. A restrictive muffler reduces this, as well as forcing the engine to operate a little like it has an EGR valve.

The downside to running an opened muffler is that you will be polluting more. I suppose somewhere there are people to whom this makes a real difference. I say stay close to home, save gas, and use that time with your toys.

 

[jokers]

Hi Sean, about the only downsides that I have seen with modified mufflers is that if enough forethought isn`t put into how the outlets are placed, your hand gets pretty hot in a long cut, and I like the style that allows you to keep a screen. As others have mentioned in other threads, there is a negative pulse that can draw junk back into the cylinder if it is not protected, and around here we have tons of mud daubers that will fly in and build a nest anywhere the can. To my knowledge that hasn`t happened to any of my saws yet( I`m thinking that I would know), but they`ve built nests everywhere else on the saws including the recesses for the bolts that hold the mufflers on and the little open cells in the recoil handle. I`ve seen it happen in an afternoon. It would be a good idea to check your carb settings afterward, I constantly monitor sound and performance, a little tweak now and then is called for. Russ

 

[bwalker]

A restrictive muffler reduces this, as well as forcing the engine to operate a little like it has an EGR valve.

A epa muffler does not work like a egr valve. A egr adds exhaust gas to the intake to cool combustion temps which lowers nox in four strokes and diesels. Two strokes naturally do this as quit a bit of residual exhaust is left in the cylinders as a result of imperfect scavenging. A epa muffler simply raises the temp of the piston and exhaustport/muffler. This tends to burn off some of the unburnt hc, but also causes piston crown/ringland temps to go way up. Not the best thing for durability in my book.

 

[eyolf]

A restrictive muffler reduces this, as well as forcing the engine to operate a little like it has an EGR

The EGR in you car works, as you say, by reducing peak flame temps in the engine. An EPA restrictive muffler impedes scavenging even more than an older version, thereby leaving an even higher percentage of combustion by-products in the fuel charge as a by-product of reducing the amount of unburned fuel leaving the cylinder.

Small two strokes are hard to control, and the regs reflect some small amount of forgiveness. The Mfgr's certainly will make the case of "look how much we have reduced NOx" as a result of their work in reducing HC emissions, as well as reducing noise levels.

Technically speaking, I concede your point, in that the burned products aren't closely metered, and arent added to the intake stream. For this reason, the effect is somewhat haphazard and less predictable...but still very real.

 

[Oregon_Rob]

I use my some for some milling and when I opened up the muffler through the front bracket as many of us have, it made it very uncomfortable for milling. The heat was deflecting back at my hand and even with gloves, it gets pretty warm. I just made a little sheet metal deflector that should help to get the heat and exhaust going away from the log and me. Haven’t had time to try it get, but it is simple enough it should work.

 

[HUSKYMAN]

Originally posted by eyolf
The EGR in you car works, as you say, by reducing peak flame temps in the engine. An EPA restrictive muffler impedes scavenging even more than an older version, thereby leaving an even higher percentage of combustion by-products in the fuel charge as a by-product of reducing the amount of unburned fuel leaving the cylinder.

Small two strokes are hard to control, and the regs reflect some small amount of forgiveness. The Mfgr's certainly will make the case of "look how much we have reduced NOx" as a result of their work in reducing HC emissions, as well as reducing noise levels.

Technically speaking, I concede your point, in that the burned products aren't closely metered, and arent added to the intake stream. For this reason, the effect is somewhat haphazard and less predictable...but still very real.

You're both off a hair, ACTUALLY an EGR valve reintroduces a % of exhaust into the intake to burn up unburned hydrocarbons. High combustion temps produce lower emissions, not higher ones. The EPA mufflers attempt to do the same thing, to act like a "poor man's catalytic muffler".

I am sure very soon all saws will have catalytic mufflers similar to the one on my Husky trimmer, and we will be gutting them and porting them

 

[don]

hazards of Muffler modifications

1. Make sure the new openings are screened to prevent something getting into the exhaust port.

2. If you are out in the woods and an EPA goverment guy sees the modification (removing EPA components) expect a ticket and get a new saw. (only heard of this once in the past and only as a rumor)

3. Previous discussions say some back pressure is necessary.
Without back pressure you burn the exhaust port

 

[eyolf]

H-man:

ACTUALLY an EGR valve reintroduces a % of exhaust into the intake to burn up unburned [HC's]

Yes, some of those unburned HC's are probably burned the second time around, but since the EGR only recycles a small percentage of the combustion by-products, the major player in burning up those HC (and some of the CO) is the catalytic convertor.

High combustion temps produce lower emissions, not higher ones

yes, that's right in the case of HC and CO emissions, but not the case in NOx emissions. Higher burn temps increase oxides of nitrogen. That's the primary reasoning for EGR...to control NOx, which has been shown to be the most dangerous (automobile-caused) component of smog.

 

[bwalker]

Higher burn temps increase oxides of nitrogen

Which is why diesels have such a hard time with NOX. Many of the diesel oems are putting egr valves on there new offerings for this reason. Problem is these vlaves tend to really soot up the oil as well as introduce nasty sulfuric byproducts to the oil/combustion chamber.

 

[HUSKYMAN]

Originally posted by bwalker
Which is why diesels have such a hard time with NOX. Many of the diesel oems are putting egr valves on there new offerings for this reason. Problem is these vlaves tend to really soot up the oil as well as introduce nasty sulfuric byproducts to the oil/combustion chamber.

Yup, thats why the big OEM diesel manufacturers are pushing the fuel industry to make some decent fuel that is not full of sulphur.

 

[bwalker]

Yup, thats why the big OEM diesel manufacturers are pushing the fuel industry to make some decent fuel that is not full of sulphur.

Its no secret that mid distallates coming out of pads1-3 are some of the worst quality in the world. No wonder we have diesel fuel that is equal in quality to Uganda's.

 

[YUKON 659]

Hey Russ, your not kidding about hot hands. It's hard to believe that the exhaust can put out that much heat. Hot enough to smoke the bark in those long cuts......watch out for the smoldering embers This is the job I did on my 372.

 

[jokers]

That`s beautiful Jeff, it looks like it came from the factory!

 

[Ryan Willock]

looks good

 

[treeclimber165]

What I don't understand is why everyone wants to wait until after break-in before modifying the muffler. Break-in consists of unmated parts rubbing against each other at extremely high speeds until they wear down to fit each other. This generates a lot of heat. EPA restricted mufflers also cause excess heat in the cylinder and exhaust port. Why make the poor saw suffer any more than it has to? Pre-EPA mufflers were not restrictive like current ones are. Those saws got broken in just fine without suffocating the exhaust down into a 3/8" hole. To wait until after break-in to open a muffler is faulty reasoning in my mind.

 

[tundraotto]

i agree with you for the first time

...and probably for the last

 

[Dennis]

Otto...I am worried about you...especially after that phone call last night......you know what I am talking about...

 

[HUSKYMAN]

Otto, are you contemplating a trip to Sweden? And its not for a tour of the Husqvarna or Jonsered plants