How to port a muffler

[staggerweed]

I read somewhere that if a Stihl MS310 has a ported muffler, it is then pretty much equivalent to a Stihl MS360 or 036.  Is this true, and if so, how does one port a muffler?  What are the other advantages and disadvantages? 

[Al_Smith]

 The word "ported " is a much over used term .The very idea that anything originating in stock form from the Stihl company as being "ported "  has to be false information .

Now all that said one must remember that in addition to being a sound deadener a modern "pressure  can " muffler is a regulating device ,not to be confused  with a baffled muffler like on a car .

As such the device ,partly because of it's volume and partly because of the baffling regulates the pressure between the exiting exhaust gasses and the incoming charge of fuel to the cylinder .So the short of it is the fact that if the old charge can't get out the new charge can't get in .

In regards to "porting " there has to be about 10,000 threads on every web forum concerning chainsaw if not more on the subject .Cutting to the chase though it consists of no more than removing the baffles and making the exit hole around 70-80 percent of the area size as the exhaust port and retuning the carb for more flow .

Now with that there are folks that like to make a zillion holes in the cover or hang cute little pipes with megaphones on them .Whatever floats you boat but looking "cool ' doesn't have thng to do with how well it runs .

[Al_Smith]

I read somewhere that if a Stihl MS310 has a ported muffler, it is then pretty much equivalent to a Stihl MS360 or 036.   

I can't make a comment cencerning a 310 because I've never seen one let alone ran one .

I will say this that an 036 in good tune is a very impressive saw for 60 cc's .

[joe_indi]

036/360 Specs

Displacement:61.5 cc Bore:48 mm Stroke:34 mm Engine power at 9500 rpm :3.4 kW (4.6 bhp) Max. torque:3.7 Nm Max. permissible engine speed with bar and chain: 13,000 rpm

MS 361 Specs

Displacement: 59.0 cc Bore: 47 mm Stroke: 34 mm Engine power  at 9,500 rpm : 3.4 kW (4.6 bhp) Max. permissible engine speed with bar and chain: 14,000 rpm

Does adding an extra nostril on one's face make one as strong  as one's elder brother even though one were a bit more faster?

[tlandrum]

a muffler modded 310 stil will not cut like a 360. i  have had both side by side and the 360 outcut the 310.

[Al_Smith]

Does adding an extra nostril on one's face make one as strong  as one's elder brother even though one were a bit more faster?

That would require first porting ones nose in a manner of speaking .Now I've seen noses with varied assortments  of hardware of sorts attached there in but never a ported version .Hmm .

[SwampDonkey]

Is this where "rip a new one" comes in?

[Al_Smith]

I've ripped a few dandys in my life but it had more to do with a combination  of pickled eggs and Budweiser than anything else .

[SwampDonkey]

Eww nasty!!

[boobap]

that would be a stink pickle   

[HolmenTree]

Yes it's funny of all the threads and advice on muffler modding. Back in the day in the logging camps I worked at, a muffler mod was taking your scrench and poking a half dozen holes in the front of the muffler. Takes 10 seconds
I have a variety of modified competiton saws, some 30 yrs old. Yes all their mufflers are gutted and relieved. Saw powerheads are a air pump increase the intake end , increase the exhaust end to match.
I'm not saying opening up a stock saws muffler won't increase h.p. What I am saying is the extra noise makes the saw seem likes it's got "alot more h.p increase" then it actually has.
Put more thought into filing your chain better.
Willard

[windthrown]

I have threads on modifying the 310, 290 and 390 mufflers on some other forums. Pictures are too hard ot post on this one. Message me if you want a link to the threads. Easy to mod the mufflers 1127 model Stihl saws. One hour and little or no money, and 10-15% power gains.

[Al_Smith]

It doesn't have a thing to do with a modern saw but back in the day my old man and myself would gut the mufflers on our PM 610 Macs and out run the 042 Stihls that were newly on the market .The Stihls had us by half  a cubic inch and 1500 RPMS stock .We had them by higher torque .

Now of course had the owners of those nice shiny saws done likewise we wouldn't have stood a chance .They didn't know about it ,we did .

Cheapest way to crank some power ,die grinder and a little time .

[nmurph]

i have a muff modded 310 and a stock 361 and 357, and i will tell you that, with the same chain and bar, the 310 is just as fast as either of these.

[Al_Smith]

Do tell .Give me about a day with each of them and a dime will get you a dollar the end results would differ .

[windthrown]

My muffler modded and tweeked 310 falls short of my last unmodified full stock 361. About 5% slower with a 20 inch bar with timed cuts, same bar and chain, same log being cut, on the same day. I attribute it to the lower revs (at WOT loaded and unloaded). But they are close, and modded the 310 is a nice saw. It also has the lowest vibration of the 1127 Stihl series. For the price difference there is a case for getting the 310 when money is tight and you need to get some wood cut.