Mod a new saw? Yep.

[Patrick62]

New 046, cut one load with it and it runs great. I did not think that pathetic exhaust hole and slot made any sense. I emailed Stihl about it, and they replied:

The
louvers
(or slits) are there to help evenly distribute emissions as well as
provide
a constriction for the exhaust gases to flow more quickly from the
combustion chamber. The quicker the exhaust gases are expelled, the
cooler
the engine will run.

You believe that stuff? I didn't either. I would like this to last over 20 years like the 041 already has. So I opened it up a smirch, the screen is still in there, but it breathes a lot better. I don't need total performance, but something a little closer to sensible.

Other than that this is one fantastic machine. Looking forward to cutting again this weekend! :blob4:

 

[whatsnext]

A constriction may cause the exhaust gases to flow more evenly, but the reason they call them constrictions, is because it's slower. If constrictions were good, for performance, they would just close the exhaust port completely and you would have a REAL quiet saw. It would never sound like it was running even. Trust your instincts on this one.
John....

 

[njforestfire]

The louvers
(or slits) are there to help evenly distribute emissions as well as
provide
a constriction for the exhaust gases to flow more quickly from the
combustion chamber. The quicker the exhaust gases are expelled, the
cooler the engine will run.

I think they are trying to say that it needs back pressure. That statement from Stihl there doesn't make sense!!! A smaller hole will create a velocity increase on the downstream side of the hole. But this will also allow for more pressure to be stored upstream of the hole (which is between the hole in the muffler and the exhaust port on the jug). I agree that the quicker the VOLUME is dispersed the cooler the engine will run and the 'louvers' to evenly displace the exhaust. I just can't believe the other statement.

Has anyone ever tried or known anyone to do any kind of flow verses temperature test?

 

[scottr]

Thread

John , timberwolf started an excellent thread http://www.arboristsite.com/showthread.php?t=6199 that doesn't have flow data but will answer heat ,noise , and performance questions .

 

[Patrick62]

Thanks for the second opinion. I will know more this weekend when I get a chance to really use it.
I think what they really had in mind was a rev limiter. corked off like that would reduce power and rpm at top speed. If they wanted a rev limiter, then they could have designed it into the ign, where we would promptly remove it....

I found it, I liked it, I bought it, I Stihl modified it.