# 455 rancher muffler mod question???????



## sethknight (Dec 30, 2009)

ok, im new to modding and theres good info on this site but none really for the 455, and I guess cuz of the x torque engine it limits effectiveness supposivly however lets say if i take out the spark screen and drill another say .25" or .40" hole next to the existing one which is like a half inch will my saw gain at least a little preformance??? and if not where the heck can I BUY A NON CAT MUFFLER. ive looked everywhere but cant find one for a 455 rancher, id really like to beef it up for fun. pleez any help, id really like to just drill another hole insted of buying one but i will buy one if i half to.

I have other more powerful saws but if i can beef up this one why not.


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## roncoinc (Dec 30, 2009)

sethknight said:


> ok, im new to modding and theres good info on this site but none really for the 455, and I guess cuz of the x torque engine it limits effectiveness supposivly however lets say if i take out the spark screen and drill another say .25" or .40" hole next to the existing one which is like a half inch will my saw gain at least a little preformance??? and if not where the heck can I BUY A NON CAT MUFFLER. ive looked everywhere but cant find one for a 455 rancher, id really like to beef it up for fun. pleez any help, id really like to just drill another hole insted of buying one but i will buy one if i half to.
> 
> I have other more powerful saws but if i can beef up this one why not.



The purpose of a muffler mod is to lessen the restriction for the exhaust..
sometimes just an extra hole in the front wont do it.
pull the muffler and find the restriction and try lesen that so the exhaust has a better,easier shot out.
thats a start anyway..


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## bitzer (Dec 30, 2009)

The 455 is a strato that means it has an extra air intake that preceeds the intake charge into the combustion chamber. This extra air forces the exhaust out instead of fresh mix forceing the exhaust out like on a traditional two stroke. The back end of the extra air also mixes with the overly rich fresh charge for better combustion. The muffler is an empty box. There are no cats or restrictions because it is a cleaner running engine. In a classic two stroke some of the fresh mix is lost out of the exhaust that is why cats are needed for the epa. In the strato there is only air coming out so no cat is needed. I did add a second port to my 455s muffler and it did create some gain, but not much. The cylinder port sizes for this engine are tiny in comparison to two strokes of similar design and the transfer ports are very long. I made some very extreme changes to my cylinder, but i also had good results. I don't think widening the exhaust on the muffler will hurt anything, but it is a little tricky to tune. Making timed cuts to tune the bell curve drop off was a lot leaner than classic two strokes. What I mean is, the saw cut faster and faster to the point where I knew the saw was way to lean. If you can tune by ear well you should be fine. Here is a vid of the Husky 455/460 that Husky sent me when I asked for their concept on the strato theory. So yes a wider exhaust port in the muffler will make a change, but very little. The power this saw will produce is very limited by its design and port sizes. Unless you are willing to port it, there is not much power to be had with just a muffler mod, there is some, but not much. Also in the saw building 101 section there is a thread called help tuning a husky 445. In the thread the 445,450, and 455 are discussed showing what others and I have found out about the Husky stratos.


http://www.youtube.com/watch?v=IY7zQKw4qsQ


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## nomak (Apr 3, 2010)

Just curious of where this saw building 101 thread is.. I did a search and come up with nothing.,..Im thinking there might be some info in there I would like to read about... thanks..


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## Terry Syd (Apr 4, 2010)

*Husky strato thread*

Here's a link to the thread - http://www.arboristsite.com/showthread.php?t=107976

You may need to read through the entire thread. We were working through various concepts as we went. Some worked, others were dead ends.

The muffler mod I recommend on the Husky stratos is to use the muffler mounting screw tubes as exhaust vents. Drill in from the sides of the muffler and put a hole in the tube (on the opposite side of the tube from the exhaust wave exiting the port). Then braze up some patches on the outside of the muffler. 

Make the hole in the tube big enough to flow the diameter of the tube. You can use a smaller drill for the muffler body and starting the hole in the tube, then open up the tube with a Dremel bit. Shine a light down the tube, while looking through the drilled hole, to see how you work is progressing.

This will vent the muffler, but won't make it as loud as if you drill a hole in the front of the muffler.

As Bitzercreek stated, if you want a significant increase in power, you will have to port the engine. The blowdown on these engines is very short, like 12-12.5 degrees. Check out the thread for more details.


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## Log Hogger (Apr 4, 2010)

*Mod it for sure*

I modded the muffler on my 445 and obtained an 8% gain in timed cuts through 13" ash. Not an enormous boost, but significant. 

There are wildly varying reports on muffler mods on Husqvarna's homeowner strato saw series: the 445/450 and the 455/460. I suspect part of the reason is the limited coils used on these saws. At least on my 445, the muffler mod put WOT rpms up against the limiter, regardless of tuning. I had to tune in the cut, and cut times were very sensitive to H set screw position. Importantly, even with the saw four stroking at the beginning of the cut, and then cleaning up in the cut (against the limiter out of the cut, start the cut and briefly four-stroke before cleaning up to a two-stroke sound), the H jet may not be set for fastest cut times. It's important that cut times are measured in big wood, because these stratos have relatively wide power bands, making it possible to lean it out for higher rpms, and still be left with enough torque to get faster cut times in small wood. You must time cuts in wood sufficiently big enough to measure torque and not just rpms.

In big wood, you'll get a feel for tuning it, just make sure it four-strokes when you lighten up on the saw in the cut. If you're not comfortable tuning a saw this way, I suggest holding off on the muff mod for now, because a tach will be useless since WOT will be against the limiter. Even stock, these saws run right near the coil limit, making them a real b!tch to tune. At least that's the case with my 445, I understand there is some variance in coils so if you're lucky your saw won't hit its limiter at such a low rpm (about 11,650 on mine).

I'll put up a thread on the muff mod, but I've got some other mods in the works and I want to present it all in one great big package. PM me if you've got any questions on that muff mod.


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