# What's The Story On Modified Mufflers On Stock Chainsaws?



## StihlRockin' (Oct 12, 2013)

Ok, I'd love to learn some stuff on using modified mufflers on stock saws. I see an ad on another site about a dual ported muffler that would work for my Stihl 044.

Here's what I think I know about ported mufflers... They are louder. They allow more pressure out therefore giving the saw a little more power. They allow the chainsaw to run cooler.

If I did get one, I heard something about changing the setting for the gas/oil mixture. Do I lean or enrich the settings for it's use? And why?

Are dual port mufflers an advantage? If so,why? Are there drawbacks?

If I got one, what other things do or should change on the saw?

Thanks,

*Stihl*Rockin'


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## old-cat (Oct 12, 2013)

If you have the tools and have good manual dexterity, you can spend zero and have a really good performing 044. Take the muffler off , take the screen out and open the outlet as far as it will go but don't go toward the front


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## sachsmo (Oct 12, 2013)

Some saws were so choked up with the factory muffler, a free flowing one is about the best bang for the buck modification.


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## lambs (Oct 12, 2013)

I've not modded one, but have read about it here on AS before the search got difficult.

Opening up the muffler seems to allow the piston to more easily move air through the saw, as it is basically a pump to begin with. When you allow the air to more freely flow, you get more air in the cylinder, upsetting the fuel mixture (making it lean). So you then need to set the carb so it provides a richer mixture to get it back to the proper ratio for that particular saw. 

More fuel, more power. 

But you can overkill this by opening the muffler too much, and then you actually lose power because some back pressure from the muffler is desireable. 

Rule of thumb is you want to open up the muffler to no more than 80% or so of the exhaust port area on the cylinder head. Which you can measure by removing the muffler and inserting raw sphagetti into the port until full, then counting how many pieces it took to fill it in. Make sure the muffler openings do not allow more than 80 - 85% of that amount, then retune the carb to get the mixture right. There are entire threads on how to tell when it is right. Basically you want it 4 stroking at wide open throttle when out of the cut, and running smoothly when fully in the cut.

If you fail to retune the carb, running the saw too lean will definitely burn it up from lack of proper lubrication (not enough fuel mixture).

Finally, if you have an older saw, it may be opened up fairly well by design (fewer EPA standards back then) so you may not gain a lot. And some newer models are using computerized fuel mixtures that may automagically compensate for the free flowing muffler mod. 

That's what I think I have learned about it from studying this site. I'm sure others will chime in with their comments as well.


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## sachsmo (Oct 12, 2013)

lambs said:


> I've not modded one, but have read about it here on AS before the search got difficult.
> 
> Opening up the muffler seems to allow the piston to more easily move air through the saw, as it is basically a pump to begin with. When you allow the air to more freely flow, you get more air in the cylinder, upsetting the fuel mixture (making it lean). So you then need to set the carb so it provides a richer mixture to get it back to the proper ratio for that particular saw.
> 
> ...




I have been here a few years and have seen the 80% figure many, many times. Is there science behind this thinking? Is there cold hard proof you need "some back pressure"?

I realize a tuned pipe actually pulses some of the wasted charge back into the combustion chamber, that is controlled back pressure (actually a charge boost)and has been studied and is proven science.

Guess my way of thinking is back pressure from restriction is NOT a good thing no matter how you roll it.

Yes I have done several and really haven't gone too far yet? If you have a carburetor that can be tuned, I fail to see the downside.


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## OH_Varmntr (Oct 12, 2013)

sachsmo said:


> I have been here a few years and have seen the 80% figure many, many times. Is there science behind this thinking? Is there cold hard proof you need "some back pressure"?
> 
> I realize a tuned pipe actually pulses some of the wasted charge back into the combustion chamber, that is controlled back pressure (actually a charge boost)and has been studied and is proven science.
> 
> ...



If I remember all of my training correctly...

The exhaust port is the first port to open and the last port to close. Because of this, tuned pipes are desireable because the back-pressure pulse is tuned to bounce scavenged fresh air/fuel mixtures back into the engine prior to the exhaust port closing. It helps with fresh charge volumetric efficiency (VE). The higher the VE, the more air is introduced into the process. More air means more fuel since the air and fuel is mixed prior to entering the cylinder.

In non-stratocharged saws there's always going to be some scavenging going on, but you want it to be as little as possible so the back-pressure pulse pushes the fresh mixture lost during scavenging back into the cylinder before it is sealed up and compressed.

Stock mufflers do the same but not as efficiently. Too muck back-pressure (can you say most stock mufflers?) can lower fresh charge VE because it restricts the flow of exhaust being pushed from the cylinder by the incoming fresh charge. This decreases emissions (which is what they want) because some of the exhaust gasses may be trapped in the cylinder for another go around, and also limits power. Kind of like an EGR circuit on modern automobiles that introduce exhaust gasses back into the intake of the engine to be re-burned. 

Too little back-pressure and it allows fresh charges to be blown out of the exhaust and not be forced back in by the back-pressure. That's the point where you've gone too far with opening up your muffler. Take your muffler off (please don't) and see how your saw runs. That proves what too little back-pressure will do to performance. 

ETA: This all applies to non-stratocharged saws. I haven't been around strato saws enough to care to learn about them.

Here's a good view of it. Tuning Two-Stroke Engines : Two Stroke Theory


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## sachsmo (Oct 12, 2013)

Resistance for the sake of back pressure is not a good thing.

Never seen a stock 'can' muffler that could be tuned for charge boost. a 'pipe' is proven science and if made properly will boost 2 stroke performance greatly.

Cans just bounce pressure waves and cause turbulence. Show me a 'tuned' can muffler, then you would have my attention.

This is the closest thing I could find for a "tuned can"


http://www.arboristsite.com/attachment.php?attachmentid=317396&stc=1&d=1381593842


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## OH_Varmntr (Oct 12, 2013)

Ok so I guess I shouldn't have say they do the same thing. The idea I was trying to relay is that "resistance" back-pressure and the back-pressure pulse are different but their end results are they both attempt to keep fresh charge from being expelled without being combusted first. 

Stock mufflers over-do it because they are also reducing both air and noise pollution. Pipes don't really care about either.

ETA: Link didn't work.


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## lambs (Oct 12, 2013)

I think OH got it about right, and well put at that. I would not pretend to have experience doing this, that's why I was qualifying my response as being based on what I have read. 

I think perhaps the goal of a muffler mod is to take the low hanging fruit in terms of increasing power. I'm sure a tuned pipe is probably a better answer if the goal is to maximize the performance of a 2 cycle engine, but for most of us it is not feasible or economical.


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## sachsmo (Oct 12, 2013)

I disagree,

pipes are tuned to a specific rpm (usually under load in the cut) if the timing of the pressure wave is off, even a pipe is pretty useless.

any pressure wave 'bounce back' in a can would be a very specific, very low rpms. Perhaps at idle. That does you no real favors at the operating rpm of a chainsaw.

I remember 2 stroke racing as a kid, everyone would talk of the "powerband" My Dad always called it "getting on the pipe" Yup he was the best engine builder I have met in my life, and he's been gone 20+ years.


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## lambs (Oct 12, 2013)

sachsmo said:


> I disagree,
> 
> pipes are tuned to a specific rpm (usually under load in the cut) if the timing of the pressure wave is off, even a pipe is pretty useless.
> 
> ...



So would you contend that a muff mod improves performance?


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## sachsmo (Oct 12, 2013)

Depends,

If you can tune for the mod, it is usually a win, especially on a choked up muffler.

Remember it is designed as a silencer. ANSI and EPA have a lot to say about what is best for us eh?


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## exSW (Oct 12, 2013)

It's not always about performance.I pulled the muffler on my Dolmar 420 and all I did was cut out the Cat and adjust the carb.Made the saw run noticably cooler(as in A LOT)and everyone knows heat kills motors.


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## Big_Wood (Oct 12, 2013)

I mod the mufflers not just for a power gain. I do it to move the port to a different location then stock. This is mostly for the husky's that have their exhaust port on top of the can right under the cylinder cover. It just bugs me having it there so on most i weld on dual ports and weld the factory port closed. Saws with ports on the side of the can are acceptable to me but i have seen to many of them husky's get wood chips in between the can and the cylinder cover. it sometimes results in a fire and melting plastic if not noticed in time. As of now i have not seen any saw that didn't benefit from a simple muffler mod.


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## tolman_paul (Oct 12, 2013)

Fundamentally an engine is an air pump and your power is limited by how much air you can pump through it. An overly restrictive muffler has essentially the same affect as a too small carburetor, it restricts the amount of air that the engine can pump and hence it's power. It also has the additional negative attribute of making the engine run hotter


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## outdoortype (Oct 12, 2013)

What makes everyone think that the saw runs cooler with a muffler mod? Have any of you guys ever measured the engine temp on stock vs modified muffler? I would think that the increased air flow and increased rpm would increase friction and heat in the cylinder thus negating any gains from otherwise. Most of the cooling is done by the evaporation of fuel and the cylinder fins providing a heat sink.


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## StihlRockin' (Oct 12, 2013)

Woah, woah woah! Back up the truck Chuck. Someone help please! My onboard 'puter thingee blew it's main flux capicitor that supports the major components of the Interpretation modules on my laptop.

So in essence...

What?

*Stihl*Rockin'


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## exSW (Oct 13, 2013)

exSW said:


> It's not always about performance.I pulled the muffler on my Dolmar 420 and all I did was cut out the Cat and adjust the carb.Made the saw run NOTICABLY cooler(as in A LOT)and everyone knows heat kills motors.





outdoortype said:


> What makes everyone think that the saw runs cooler with a muffler mod? Have any of you guys ever measured the engine temp on stock vs modified muffler? I would think that the increased air flow and increased rpm would increase friction and heat in the cylinder thus negating any gains from otherwise. Most of the cooling is done by the evaporation of fuel and the cylinder fins providing a heat sink.



Any more questions?


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## z71mike (Oct 13, 2013)

StihlRockin' said:


> Woah, woah woah! Back up the truck Chuck. Someone help please! My onboard 'puter thingee blew it's main flux capicitor that supports the major components of the Interpretation modules on my laptop.
> 
> So in essence...
> 
> ...



Just cut your muffler open a little bigger and retune. You'll like the result.


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## shawn.m (Oct 13, 2013)

*Just cut it*

Did muffler mod on my 372xp years ago, tuned it up with more fuel, unlimited coil. 
Skip chain and this thing still rocks! 
Less back pressure equates lower pumping loss, more fuel equals more power when tuned. 
Did muffler mod on 372xp, rancher 55 and cheapo Poulen .. All responded to muffler mod with more power and quicker to rev.


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## outdoortype (Oct 13, 2013)

exSW said:


> Any more questions?



No point in being smart alec. Did you actually measure the engine temp? I know the cat mufflers get hot but most of that is around the cat plate. I tested a cat saw and the engine temp gain was not significant.


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## exSW (Oct 13, 2013)

outdoortype said:


> No point in being smart alec. Did you actually measure the engine temp? I know the cat mufflers get hot but most of that is around the cat plate. I tested a cat saw and the engine temp gain was not significant.



I actually do use an IR thermometer on friction points and bearing surfaces on many of the pieces of equipment I own and operate as 20-30 degree differences are harder to determine.On this saw however the difference was SO SIGNIFICANT that a test of that sort was pointless.When the heat of the cat equipped muffler scorches the saws adjacient plastic cladding and you can feel it heating up your left hand as you operate the saw you know it's to hot.What were the parameters of your test?Was it a cold or hot day?How long did you run the saw?How long did you run the saw under load?What was the nature of the wood you were cutting(hardwood,softwood,species)?I bought a brand new saw and cut aprx 10 cord of wood in a about a three week time frame.Ran several Gallons of gas through said saw before I voided the warranty and cut out the cat.


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## Yukon Stihl (Oct 13, 2013)

outdoortype said:


> What makes everyone think that the saw runs cooler with a muffler mod? Have any of you guys ever measured the engine temp on stock vs modified muffler? I would think that the increased air flow and increased rpm would increase friction and heat in the cylinder thus negating any gains from otherwise. Most of the cooling is done by the evaporation of fuel and the cylinder fins providing a heat sink.



It makes sence that a modded muff will run cooler because the hot gas can escape faster so the hot gases have less time to heat the cylinder and muff.
There shouldn't be any evaporation of fuel the idea is to burn it for power.
So the fins that are on the flywheel are just for looks?Maybe you should break them all off for extra power.Sometimes the saw builders will lighten a flywheel for more power.Looks like they can save some lathe time and just use a pair of vice grips and break the fins off the flywheel.They serve no real purpose,.....or do they hmmm.
Thomas


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## Big_Wood (Oct 13, 2013)

Fuel does reduce heat but not because of evaoration. A properly tuned mixture will add a small amount of extra fuel displacing what would otherwise be air. This added fuel and less air makes for cooler combustion because not all of it can be combusted by the paricular engine being tuned. The end result is unburned gases that actually soak up some of the heat from combustion and send it out the exhaust. What i'm saying is this is very similar as an egr valve in a car works. The egr valve sends unburned exhaust gases back into the intake to displace the combustable mixture soaking up heat in the process. A 2 stroke without that extra fuel will not last long as they overheat which results in cylinder scoring. A 4 stroke on the other hand will actually run for quite a while, producing severe NOX emissions until you burn a hole in a piston. 2 strokes generally don't make it to that point but i have seen it happen on rare occasions. Muffler mods do make your engine run cooler. Yer pumping more but yer expelling heat faster. Heat from top end friction will be expelled out the cooling fins for the most part.


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## outdoortype (Oct 13, 2013)

exSW said:


> I actually do use an IR thermometer on friction points and bearing surfaces on many of the pieces of equipment I own and operate as 20-30 degree differences are harder to determine.On this saw however the difference was SO SIGNIFICANT that a test of that sort was pointless.When the heat of the cat equipped muffler scorches the saws adjacient plastic cladding and you can feel it heating up your left hand as you operate the saw you know it's to hot.What were the parameters of your test?Was it a cold or hot day?How long did you run the saw?How long did you run the saw under load?What was the nature of the wood you were cutting(hardwood,softwood,species)?I bought a brand new saw and cut aprx 10 cord of wood in a about a three week time frame.Ran several Gallons of gas through said saw before I voided the warranty and cut out the cat.


why would would it matter if it was a cold day or hot day or what size/type wood? 
The adjacent plastic on a cat equipped saw is melted due to the extra heat of the exhaust gas. Awhile back another member tested this and the exhaust temperature was much higher on the cat equipped saw. This however, does not directly translate into the engine running hotter. My test was done on a 87 degree day with high humidity. I warmed the saw and made about 10-15 cuts. I bought a used saw with a cat muffler (359) and wanted to see just how hot that baby would get. The cut was done in a 20" chunk of pine and I measured the cylinder and the muffler with a fluke IR thermometer. The front of the muffler was around 400, the cat plate was around 700, and the top of the cylinder was 300. The transfer covers measured considerably less I don't remember exactly. Within a few seconds, the cylinder dropped to 250. Within about 15-20 seconds, it dropped to around 190. The saw was turning 9000-10000 RPMs in the cut. I don't remember the exact temp of the non cat 359 I tested before because I expected the difference to be much greater than it was. Regardless of wood type, I would bet that any saw turning 9-10,000 in a cut for a duration of 15-20 seconds in that kind of weather would measure fairly close regardless if it had a cat muffler or not. Most of the heat is generated by the friction and RPM. 

Westcoaster,
Fuel does cool the engine because it can not turn to vapor without absorbing heat. The fins on the cylinder are there to help carry/dissipate the heat. 
Yukon
I have no idea why you mentioned the fins on the flywheel.


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## tolman_paul (Oct 13, 2013)

outdoortype said:


> What makes everyone think that the saw runs cooler with a muffler mod? Have any of you guys ever measured the engine temp on stock vs modified muffler? I would think that the increased air flow and increased rpm would increase friction and heat in the cylinder thus negating any gains from otherwise. Most of the cooling is done by the evaporation of fuel and the cylinder fins providing a heat sink.




The hottest thing in an engine are the exhaust gasses that are at about 1200 deg F. If instead of completely purging them from the cylinder with a fresh charge of air and fuel part of them linger in the cylinder due to muffler back pressure then the engine will most definitely run hotter. So a restrictive muffler will makers power by limiting the amount of air and fuel you can put in the engine and will cause it to run hotter by not purging all the hot exhaust gasses.


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## outdoortype (Oct 13, 2013)

tolman_paul said:


> The hottest thing in an engine are the exhaust gasses that are at about 1200 deg F. If instead of completely purging them from the cylinder with a fresh charge of air and fuel part of them linger in the cylinder due to muffler back pressure then the engine will most definitely run hotter. So a restrictive muffler will makers power by limiting the amount of air and fuel you can put in the engine and will cause it to run hotter by not purging all the hot exhaust gasses.


How would you ever know how much exhaust gas is being purged one way or another? However you do know that more rpms generate more friction which does equal heat. Most muffler mods increase performance by increasing RPM. If you're going to open the muffler and then richen mixture back to stock RPMs then I can believe the theory. But who does this?


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## OH_Varmntr (Oct 13, 2013)

outdoortype said:


> If you're going to open the muffler and then richen mixture back to stock RPMs then I can believe the theory. But who does this?



Folks that mill. And it helps, imagine that.


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## 1270d (Oct 13, 2013)

Could somebody provide a link to a video showing two identical saws, one stock with muff mod and one bone stock, running side by side. How many percent gain is there? 5?


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## chadihman (Oct 13, 2013)

http://www.arboristsite.com/chainsaw/240387.htm

This was a test I did on my dyno with my oem MS 460. The muffler mod was very impressive.


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## 1270d (Oct 13, 2013)

I'm interested. Your test shows roughly 20% gain?


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## z71mike (Oct 13, 2013)

Sounds about right.


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## outdoortype (Oct 14, 2013)

OH_Varmntr said:


> Folks that mill. And it helps, imagine that.


how many muffler mod videos you see milling? Most mod to increase performance via rpms, imagine that.


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## shawn.m (Oct 14, 2013)

*Disagree*



outdoortype said:


> how many muffler mod videos you see milling? Most mod to increase performance via rpms, imagine that.



My 372 didn't really increase rpm as much as gain hp throughout the curve. This means I can take bigger bites of the wood without bogging down. Before muffler mod I was slower through the cut 
That is why I did muffler mod with rejet . More power in cut as almost my wood is oak


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## Yukon Stihl (Oct 14, 2013)

[QUOTEYukon
I have no idea why you mentioned the fins on the flywheel.[/QUOTE]

Hi Outdoortype
I mentioned them because they do most the cooling.They are the fan that blows cooler air past the fins on the cylinders.


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## Stihlman441 (Oct 14, 2013)

1270d said:


> Could somebody provide a link to a video showing two identical saws, one stock with muff mod and one bone stock, running side by side. How many percent gain is there? 5?



Get your stop whatch out
Stock 441CMTronic same chain,bar in each vid,top wood is soft Pine bottom wood is hard Yellowbox.

Stock

[video=youtube;bKiNyhBS0OE]http://www.youtube.com/watch?v=bKiNyhBS0OE[/video]


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## Stihlman441 (Oct 14, 2013)

Stock with muff modd

[video=youtube;exwpA0mjccY]http://www.youtube.com/watch?v=exwpA0mjccY[/video]


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## MCW (Oct 14, 2013)

outdoortype said:


> how many muffler mod videos you see milling? Most mod to increase performance via rpms, imagine that.



Results vary between different saws but a muffler mod on my 3120 definitely helped when milling - very noticable with a 60" bar (55") cut and bar buried in hardwood. It won't rev any harder with a fixed high jet and rev limited coil but did noticably increase the torque.


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## wyk (Oct 14, 2013)

1270d said:


> I'm interested. Your test shows roughly 20% gain?



I was impressed as well, and that is with the stock dual ported muffler vs non dual stihl muffler. It goes to show how stopped up some of the newer saws are.
I don't know about less heat, or whatever. But I do know every saw I have modded the muffler on has shown an amazing improvement in performance and responsiveness.


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## OH_Varmntr (Oct 14, 2013)

MCW said:


> Results vary between different saws but a muffler mod on my 3120 definitely helped when milling - very noticable with a 60" bar (55") cut and bar buried in hardwood. It won't rev any harder with a fixed high jet and rev limited coil but did noticably increase the torque.



Exactly. More exhaust gases expelled equals more room for fresh air/fuel charge to be utilized by the same cylinder volume, which equals more power. 



outdoortype said:


> how many muffler mod videos you see milling? Most mod to increase performance via rpms, imagine that.



Many folks that mill run modded mufflers. I don't need to see videos to know that. A simple search will turn up plenty of examples for you. Nothing to do with higher RPMs for milling and the MM _still_ impresses with more power.

ETA: My MS460 is all stock and I've been wanting to MM it for awhile now. I'll throw my tach on it, cut a round and video it. Then I'll MM it, tune it to the same RPMs as before, cut a round and video it. We will time it from there and see the results. Do you think it will be the same?


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## tolman_paul (Oct 14, 2013)

outdoortype said:


> How would you ever know how much exhaust gas is being purged one way or another? However you do know that more rpms generate more friction which does equal heat. Most muffler mods increase performance by increasing RPM. If you're going to open the muffler and then richen mixture back to stock RPMs then I can believe the theory. But who does this?



If the majority of the heat came from friction than running the saw wot at no load which is it's highest rpm would create the highest heat, and loading up the saw in a cut and dropping the rpm would cause the saw to run cooler. But, the exact opposite occurs. The saw run's it's hottest when at it's lowest rpm being worked in a cut.

Muff mods work because they allow the engine to pump more air and fuel through the engine which allows the engine to produce more power and run cooler.

About 20 years ago I decided to see how quiet I could make a dirt bike, so I welded a washer on the end of the muffler. It dropped the exhaust noise considerably, but I also got detonation from the engine running too hot.


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## 1270d (Oct 14, 2013)

Stihlman441 said:


> Get your stop whatch out
> Stock 441CMTronic same chain,bar in each vid,top wood is soft Pine bottom wood is hard Yellowbox.
> 
> Stock
> ...



So just using the vid timer it looks like your muff mod gained you 2 -3 seconds in a roughly 32 second cut. Not anywhere near a twenty percent increase the dyno guy put forth.


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## OH_Varmntr (Oct 14, 2013)

I don't think comparing dyno results to time results is an apples to apples comparison. Different variables.


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## chadihman (Oct 14, 2013)

OH_Varmntr said:


> I don't think comparing dyno results to time results is an apples to apples comparison. Different variables.



The dyno reads the torque and HP at any rpm at the end of the chain. I think its as close to real world HP as possible. The dyno is probably a bit better at deciding if a certain mod made more power than testing in timed cuts in wood. The dyno tells if your saw is making power and then its important to match the right sprocket and chain to use the power efficiently.

Don't get me wrong. Timed cuts will show improvements and its fun.


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## wyk (Oct 14, 2013)

1270d said:


> So just using the vid timer it looks like your muff mod gained you 2 -3 seconds in a roughly 32 second cut. Not anywhere near a twenty percent increase the dyno guy put forth.



He didn't test a 441CM, but a 460. Still, in that video, that is a 10% increase in cutting speed with a simple mod that only takes a few minutes. Compared to how much time and money you could spend on a car or bike to get 10%, let alone 20, it is a no-brainer. The OP stated he had a single port 044. These are similar enough to a 460 that the OP could expect some significant gains with the dual port muffler. The 441CM is a computer controlled chainsaw, and in a completely different league and time zone. The fact it gains 10% even whilst being computerized shows the mufflers are restrictive from the factory. I personally know several folks that use muffler modded saws for milling(one of which I used first in forestry), as well as for professional work. I have also used a muffler modded and several ported chainsaws for professional work. Mufflers are cheap. If a 10% gain scares you, don't do it.


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## Big_Wood (Oct 14, 2013)

Concentrating on muffler mods i completely overlooked the op's post and didn't even notice he was talking about a dual port on his 044. To the op. get that dual port muff half or make one out of your existing half and never look back. Every stihl 044/440, 046/460, 064, 066/660 i have ever run with a dual port has had a nice edge over a stock saw even without porting. You will be grinning big


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## 1270d (Oct 14, 2013)

I'm game to try it. No harm done if it doesn't please me. Prolly do it to a 385


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## OH_Varmntr (Oct 14, 2013)

chadihman said:


> The dyno reads the torque and HP at any rpm at the end of the chain. I think its as close to real world HP as possible. *The dyno is probably a bit better at deciding if a certain mod made more power than testing in timed cuts in wood.* The dyno tells if your saw is making power and then its important to match the right sprocket and chain to use the power efficiently.
> 
> Don't get me wrong. Timed cuts will show improvements and its fun.



I absolutely agree. I was simply stating that you cannot expect a 20% increase in dyno power to equate to a 20% decrease in cutting time, _all other things being equal_.


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## Big_Wood (Oct 14, 2013)

1270d said:


> I'm game to try it. No harm done if it doesn't please me. Prolly do it to a 385



Oh yer gonna like it and it will please you. My 372 muffler get all bent up there a couple months ago. Replaced it with a stock muffler. Old muff was just a mod to the factory opening. I started working on a dual port the other day but my mig ran out of welding wire  hopefully i will get some soon so i can finish it. Buying welding wire where i'm from just isn't cost effective so i'm gonna wait til i go out of town next. I'll upload a pic when it's done. It is gonna be bad ass . Adding dual ports and a little bit of area in the top corners in the process. It is fun experimenting with different types of muffler mods. My preferred mods alway require welding. Once you start modding mufflers you can't help but to mod them all. That's how i am at least


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## DocMurphy (Nov 5, 2016)

So are there any good Muffler modifications I can do to my Husqvarna 281 which is in pristine condition

Sent from my VS986 using Tapatalk


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## weimedog (Nov 5, 2016)

outdoortype said:


> how many muffler mod videos you see milling? Most mod to increase performance via rpms, imagine that.



Have to throw in a comment or two. I disagree with the premise that most mods to increase performance are about increasing RPM's. For me many saws also have limited ignition coils. The Husqvarna 372 X-Torqs, 576xp; etc. are examples that come to mind. Certainly you can change the port timing, increase x-sectional area of the transfers etc. along with going with an unlimted coil to jack power and RPM's. Now you have spent 1/2 the price of a new saw in grind time (Time is money) and a decent ignition (Not $15 dollar AM junk)! But that isn't the only way to boost performance. Compression alone can make a huge difference. That's why for a long time simple base gasket deletes for many of us and then pop-up piston builds have been a staple of performance hops. Compression increases work well to boost power at "standard" RPM's by increased efficiency of the actual combustion, and along with the right "squish"; actually increases the amount of charge burned vs. a standard squish distance typical of a stock saw. Its about performance increase vs. dollars & time spent. Of course that's effected by what tools and skills you have vs. have to hire out! I do my own work. I might not win any cookie cutting contests but I have fun, cut a chit load of wood....and really enjoy a sharp chain on one of my own builds when out in the woods making chips...

As someone mentioned before power isn't the only motivation for muffler mods...and as you mentioned before the muffler and cylinder temps do raise in cuts only to rapidly drop...on THAT saw. Some of the new designs have, for reasons only known to the designers; (suspect epa/efficiency) trapped the heat and radiate that heat through the bottoms of their mufflers back to the cases. On a hot day with longer than 20inch or 10second cuts this does increase the saw's overall temperature. Some even have heat soak related re starting issues when other factors are added to an already heat stressed situation. Smart muffler mods can help heat escape with obvious benefits. And yes I have measured cylinder temperatures.

For the typical hobby wood cutter type cheap performance increases done by them on their own saw can be worth more than the most sophisticated built saw done by someone else. Things like muffler mods along with increases in compression with no base gasket builds ( On some saws) returns the instant gratification of seeing a difference that is priceless for the tinkering crowd who prides having ownership and interaction with their mechanical hobby of choice. Same metric with Cars, Motorcycles, even firearms. And as always every saw is an individual so some will see greater changes than others....but the bottom line is on the saws where its possible a compression gain along with a muffler mod makes a noticeable difference at minimal cost. And its your mod.

Oh yea....its REALLY easy to get caught up into the online measuring stick mentality and really over analyze this crap! Stock saws have cut a LOT of wood for a very long time!


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## DocMurphy (Nov 6, 2016)

I do agree I have mostly used stock except a bar or chain over time and I've cut loads of wood and still going

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## Gypo Logger (Nov 6, 2016)

westcoaster90 said:


> I mod the mufflers not just for a power gain. I do it to move the port to a different location then stock. This is mostly for the husky's that have their exhaust port on top of the can right under the cylinder cover. It just bugs me having it there so on most i weld on dual ports and weld the factory port closed. Saws with ports on the side of the can are acceptable to me but i have seen to many of them husky's get wood chips in between the can and the cylinder cover. it sometimes results in a fire and melting plastic if not noticed in time. As of now i have not seen any saw that didn't benefit from a simple muffler mod.


My 372 muffler that Cahoon welded a port in finally got a resonance fracture, so I replaced it with a stock muffler without the spark arrestor and there doesn't seem to be any less noise or power.
Often times the stock port becomes crushed closed from using gloved hands. That's where the bar wrench comes in handy.


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## SeMoTony (Nov 8, 2016)

I first took muff off,matched gasket opening 2 cylinder port. Flopped gasket onto muff & matched into muff opening. That helped enough 2 notice sent 4 dual port cover opened lil ports pulled limiters tuned. Cut with grin. went to auction bought old 066 runner doing top end.Next auction 064 disassembled kit 2 b 91cc when reassembled. Max flo AM air cleenr added to flo on ms 460 so all three will have. Moral of this story : avoid CAD exess xsitement sawing wood and xpenses leave her stock & let dealer do the work ;-)


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