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

[tolman_paul]

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.

 

[1270d]

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]

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.

 

[OH_Varmntr]

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

 

[chadihman]

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.

 

[wyk]

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.

 

[Big_Wood]

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

 

[1270d]

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

 

[OH_Varmntr]

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.

 

[Big_Wood]

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

 

[DocMurphy]

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

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[weimedog]

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 **** 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!

 

[DocMurphy]

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]

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.

 

[SeMoTony]

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 ;-)