Part Six: The Exhaust System

[~WBF]

Can Engineers be 'blind'?

I will always come into their trade and know things that they don't but they will never come into my trade and know things that I don't. They need an alliance to own the ultimate understand and I only need a person to be a tree length and a half away. Haha

Signed with love

 

[NCFarmboy]

Wish I could like that post 100 times. Always said engineers should have to work in the field 5 years before they could draw a set of plans.
Shep

 

[Basher]

Possible as many variables as sharpening and filling through different activities and species of wood. Everything has a different outcome.

Has there been any consideration between hard rubber mounts and AV mounts from you engineers in relation to back pressure? Do you build them different? or build them so it works for both? or you guys just here learning?.

Back pressure depends more on the muffler bearings than the AV used even though springs are better for absorbing vibration than rubber, long bars destroy springs faster.

 

[~WBF]

Back pressure depends more on the muffler bearings than the AV used even though springs are better for absorbing vibration than rubber, long bars destroy springs faster.

Is that the long standing joke said to somebody that doesn't know much about mechanics and is answered with...."I think it must be the high speed muffler bearing". Or are you talking about the 'bearings' (position) of the outlets? Start with this and I'll address the rest

 

[MustangMike]

He's shoveling Stuff!!!

 

[Basher]

He's shoveling Stuff!!!

Yup, muffler bearings , rolling,rolling.

 

[Lightning Performance]

This is all about the exhaust, remember. Your Welcome

 

[Basher]

Is that the long standing joke said to somebody that doesn't know much about mechanics and is answered with...."I think it must be the high speed muffler bearing". Or are you talking about the 'bearings' (position) of the outlets? Start with this and I'll address the rest

It`s just a dance Jame.

 

[~WBF]

Wish I could like that post 100 times. Always said engineers should have to work in the field 5 years before they could draw a set of plans.
Shep

That would be nice. My first ported Walkerized 357 was in 2006 and it was bad azz.. Even with the non rev limiter coil, the only way I could get it to smooth out was by leaching the low and closing the high off. (Was a slashing saw & for smallish tree snag falling) 2 thousand times on and off the trigger per day. It was limited by the jet and not the coil. The tweak on the low could get it to the sweet spot but unlike the 372 and bigger saws...it created a hard start with out a bog in jet. It's all about time money and comfort first and foremost.. Comfort is not debatable. You turn low back a 1/4 turn to start or have to pull cord for 3-5 min or wait it out or one could manually prime it? If the Packer was doing his/her job right then I would fill it running on it's side. (Common move in the winter north at times also) Having said that, if I had fell a 26"-30" cottonwood over a 12' wide mulcher line and I have to make 6-7 blocks then you turn the low back a 1/4. on that saw and life is good.
-----------------
Anyway roll with it.
Had to tell you that story to get to this story.
Probably after a couple 28 day shifts I get a buzz out of the the saw. Probably already happened 300 times and 285 times were in my head...lol ...But this buzzzz is here to stay. It was driving me crazy. I noticed the front of the tank was splitting about an 1" or 1"1/2 down. So I strapped it with an aluminium strap and a couple screws. She was good for another month or so and it gets rough again? I could see a rub on the case. I took the tank off and took my round file to the inside sharp edge and rounded it really deep for about 8 inches in length. Life was good again. I sacked the body of that saw out in a solid 6 months. It was over a 7 month new to old. I wore the plastic out off the upper throttle straight rod until it slipped and jammed. I have 28 yrs to say it is impossible to kill a 2 or early 3 series Husqvarna engine before the body unless you make a fatal mistake.

Hadn't needed a 357 for a few yrs but I bought one with a bad piston for $150 and throw my top end & MM on with a new ring. ..Put the strap on the front of the tank. (It was splitting also...they all do)
I pulled the tank off and went to file the tank and surprise surprise, Husqavna had corrected the issue and was identical to my mod I had done a few years previous. They don't usually fix stuff. (Or know about it. Never did they fix the spitting of the tank? That is a vibration you don't want.

I have most excellent related Raven story as well Forestry engineers also. You guys got to hear the Raven story... If that doesn't open our minds then..?

 

[~WBF]

This is all about the exhaust, remember. Your Welcome

A family friend and mentor once said. "Always listen to what people have to say. Then you can decide".

 

[rogue60]

Clarification … I said it works on "some" saws, not all. I think it depends on a lot of other factors, but I have seen a few 660s that prefer a modified baffle (rather than just removing it). I have other 660s that don't like the modified baffle.

I think it has something to do with the saws porting, and more specifically blowdown, but I don't pretend to have all the answers, I'm just posting my observations and trying to learn.

Also note that in TM's testing it was a fully ported saw, and all of his outlets are screened (which result in about 50% less flow). Most of my saws are not screened.




I believe this is what was happening on some of my saws.

On stock and very mild ported Aussie 066/660 I found they lost torque with a gutted muffler (no baffle) not to mention way to loud to run all day every day.
It didn't take much testing to work out stock mufflers on the ms660 made more power in the hardwood I was cutting.
That was with the Aussie 066/066 we didn't get the EPA American eco ms660 here I emagine they could do with a better flowing muffler or not?
Here's a pic of the last of the ms660 saws we got here before the not so mighty ms661 took over the show.
Stihl claim on paper the last of the Aussie 660's made 7.2 hp how much truth is behind that is anyone's guess? in hand to me it felt the Aussie ms660 had more low down torque than the ms661 in really hard hardwood here in softer timber the ms661 cuts fine and could hold it's revs up higher where it likes to live. Just my 2c

 

[~WBF]

Yup, muffler bearings , rolling,rolling.

and the bearing on the saw go round and round...
round and round ..round and round...

It`s just a dance Jame.

And the wheels on the bus go round & round..round r & round.

Right on man . How are you keeping?
Maybe it was part a joke but a did agree with some. Friends call me Jame. That's cool my friend.

 

[Basher]

Any muffler with a front facing outlet will be loud, an outlet on either side will be much quieter and still flow well. I could never stand running the OEM Stihl dual port design.

 

[Basher]

and the bearing on the saw go round and round...
round and round ..round and round...



And the wheels on the bus go round & round..round r & round.

Right on man . How are you keeping?
Maybe it was part a joke but a did agree with some. Friends call me Jame. That's cool my friend.

I am not an enemy.

 

[~WBF]

I am not an enemy.

Bless you friend. Nor am I to anybody. Sometimes you have to be edgy to get people back involved. Never personal.

It is not what I do for a living and they all know 99.9% at I don't but a feel a know that 1/1000 that they don't.. due to my time on the saw. So I always feel like I hold some kinda weird secret. So let's be quite...OR NOT..haha all in fun

 

[Lightning Performance]

On stock and very mild ported Aussie 066/660 I found they lost torque with a gutted muffler (no baffle) not to mention way to loud to run all day every day.
It didn't take much testing to work out stock mufflers made more power in the hardwood I was cutting.
That was with the Aussie 066/066 we didn't get the EPA American 660 here I emagine they could do with a better flowing muffler or not?
Here's a pic of the last of the ms660 saws we got here before the not so mighty ms661 took over the show.
View attachment 186861

I found two different oem north american mufflers to make one like yours. Took out my side outlet screen. Its crazy loud with the front one out. Put that front back in. The mill is getting a screw in side pipe and closed front cover. Using a small hole can and putting the screen back in that one.

 

[~WBF]

Any muffler with a front facing outlet will be loud, an outlet on either side will be much quieter and still flow well. I could never stand running the OEM Stihl dual port design.

Not necessarily. A lot of variables.
The 372 Xtorq has a completely different flow from the OE. It's front orientated. You make an oval in the front muffler strap with a screen and it's got 'throat'.
It's weak with an OE. It doesn't have the same flow. The OE 3 series are orientated to the right flow forward. If you idle the 357/372 oe triple ports in the cold too long on a job with little activity then they start to make
sh—ty hand warmers on the left flow as it will shut off in the cold on that side.
I reach to the right to warm up and my fingers kept getting shorter. Just an example

 

[~WBF]

I don't have a set formula, but what seems to be working for me on most saws is adding a second exhaust port roughly the same size as the factory port, maybe a little smaller, before any baffles if there is one. I haven't opened up any mufflers to remove baffles as of yet, but I think that is because I have been able to work around them with the particular models I have done. The muffler on my 372 is just an open can, my 357 has a baffle, but placing the extra port behind the seam lets exhaust out before the baffle comes into play. My main goal is to let the heat out a bit easier and more efficiently since these saws are spooling higher than stock.

First pic is my 372 muffler mod, second is my 357, third is my 394, all are ported, 394 with the most extensive work done. All are very strong runners. With the 372 and 357 I used 288 deflectors and screens, 394 got a Red97 deflector with no screen and I also cut off the baffle in the factory deflector. View attachment 69175 View attachment 69176 View attachment 69178

How do on god's earth do you get the screws to stay in? Sink Brass and drill again? I have had heat cut the screw in half and drop into the muffler. Not as heavy as those though. Those are good.

 

[tree monkey]

 

[~WBF]

Ahhhaahhah. You answered all my questions. Erm..cork it and screw it ..er. UM..screw them and cork em?
I would eat the cornels out of her crap just so I could say we had lunch together.