my first muffler mod!

[NWCS]

hey all, did a little searching and math.. came up with a prototype muffler mod that is all my own. just ran the saw for testing before the pic and wow it really does have a LOT more grunt! before mods in a full 32" rip cut (tested on an old stump) saw constantly stalled and was just embarrasing.. now i only stalled the chain once and can just lean WAY into that handle. retuned the carb to keep the RPMs up in extreme load.. but out of the no load would feel too rich to most people. mod actually dont look that bad to me either!

what do you all think of my first very successful try?

 

[NWCS]

by the way i forgot to mention the muffler modded saw is my Stihl 044
32 inch bar is going to be pulled and replaced with my 24incher to get even more speed out of it.

 

[pbtree]

Perhaps a sprocket change would up the speed a bit for ya...

 

[scottr]

mod

dedcow , what was the previous muffler outlet and is that one inch tubing now ?

 

[paz]

mate if its not a stupid question,,what did you base your searching and math on to get that size pipe???

 

[rmihalek]

I thought the formula was pretty simple: measure area of exhaust port at the cylinder. Take 85% of this value and that's as big as you want the opening on the muffler to be for max performance. Any larger just makes more noise.

 

[Max]

That is going to be a RIOT when it is face down in a stump.

Debis is going to be everywhere.

Don't get me wrong...I'm not knocking it...just picturing it in a stump.

 

[tony marks]

just put a screen over it,if its a concern.

 

[ripper]

muffler od

get stihl other half of dual muffler outlet than put a 8 pin sprocket on it

 

[NWCS]

there was indeed some math involved. the pipe is 3/4" ID square. im now running an 8T sprocket and a 24" big tip stihl bar (early Rollomatic from my 041 Super) with a brand new stihl RS 3/8x.050 full skip chain.. soon to be replaced modded full comp chain.

 

[ozflea]

Bet the racket it makes stirs your heart, but cannot see were it helps really.

 

[NWCS]

air flow is everything.. i may try doing some LIGHT porting on it since the cyl in the saw looks sad allready.. only reason im willing to mod this saw and experiment is this was a free saw. if i mess it up.. easy enough to afford another $99 piston/cyl kit. will need that kit anyway.

 

[scottr]

%

dedcow , what is the percentage of exhaust port area for the 3/4" I.D. tubing ? How did you like the performance compared to the stock outlet ?

 

[NWCS]

my modded port is exactly 96.4% of the head port. with roughly .8" length and a forward slant to the pipe to keep the exhaust away from the hands at all times, and still not catching on the log or presenting any problems so far.
power increase was VERY supprising as i went into it not expecting much. was after high exhaust flow with somewhat of a tuned pipe function.. now never having run a saw with a tuned pipe i can not truly compare. total mods took me around 2.5 hours and was MUCH more than just welding a pipe on and running it..

 

[scottr]

screen

Dedcow , thanks for the information . Did you keep the factory spark arrestor screen ?

 

[NWCS]

no, a screen would have messed with my tuning too much, the ONLY thing stock left is the muffler shell. inside of the muffler has been reworked for flow and im still tuning the deflection area tuning how the exhaust shockwaves can be used for my tuning. soon the cover may not even be stock anymore.

 

[paz]

thanks for the info ded....not to hi-jack your thread,,,but do you or anyone know of somewhere i can do some reading or get info for design/formula's for expansion type muffler sizes??

 

[scottr]

Thread

Paz , here's a thread to start http://www.arboristsite.com/showthread.php?t=4175

 

[Chainsaw_Maniac]

That's a pretty nice job deadcow.

It sure beats the heck out of what I've done: basically take of the muffler cap of and drill about 20 small holes in it. (It lets the air though yet catches the sparks without need for a grate).

 

[Locoweed]

My version

Opening the exhaust port in the muffler generated a lot more heat directed toward the chain brake handle. I don't think the little piece that is supposed to direct the flow toward the front was very effective.

Take one little piece of steel, a bunch of hammering, my first brazing job and presto, it it now directed toward the front.

I didn't pay much attention to the math, I wanted it to fit and have a reasonable amount of clearance from the plastic etc.