Part Six: The Exhaust System

[TreeLife]

Like the dual 1" on the husky?

More or less

 

[cus_deluxe]

^^^Holy crap on pic #1!!^^^

lol, maybe @Hedgerow can put up a pic of the muffler on his 346...

 

[RIDE-RED 350r]

Ok, let's talk about this. If he carved a BIG hole and smoked the saw. It must have run leaner, which in my eyes is burning more efficiently and completely. Should make more power...being it would get tuned properly

Would it? Or would a BIG hole diminish the scavenging effect requiring more fuel?? Honest question...I know with tuned expansion chamber exhausts, the stinger length and diameter has an effect and plays a role

 

[Deets066]

Would it? Or would a BIG hole diminish the scavenging effect requiring more fuel?? Honest question...I know with tuned expansion chamber exhausts, the stinger length and diameter has an effect and plays a role

Not entirely sure, that's the good thing about these threads. You get a lot of opinions and theory

 

[TreeLife]

With the shape of the muffler being that it is, I doubt much if any scavenging occurs. It needs more fuel because air is passing thru more easily when there is absolutely no exhaust restriction.

 

[cus_deluxe]

Would it? Or would a BIG hole diminish the scavenging effect requiring more fuel?? Honest question...I know with tuned expansion chamber exhausts, the stinger length and diameter has an effect and plays a role

im sure you are right, that a big hole does diminish the scavenging effect, but that doesnt mean less power, just more fuel used, hence the need to retune. i know the guys makin 3 (or 2.5...) cuts in cant races couldnt really care less about fuel consumption. obviously a different story for the firewooder/logger/tree service guy.

 

[mdavlee]

Brian W Aka "timber wolf" had a spread sheet on hole sizes with stock carbs .He showed graphically that anything above about 125 percent was detrimental .Fact anything above 80-85 percent didn't show much gain ."Zander" down Cinci way cooked an 880 by carving out too big of a hole and not retuning .tried to sell the saw on flea bay for next to nothing .I tried to tell him but -----well chit happens

Seems the husky don't mind bigger outlets like the stihls.

 

[drf256]

Anything I've done with a side outlet and a flat front had made the same power and less noise.

I did buy Stainless measuring/sauce cups of varying sizes off of amazon to try in mufflers, but they won't ever be able to reflect back what a tube with an expansion chamber can.

Next for me is to cap the inside part of my outlets inside the muffler to prevent any of the exhaust from escaping the openings directly. Kinda custom baffling.

The more the exhaust pulse swirls, the more random sound wave canceling effect occurs.

Like Mason said, the volume can sometimes be close, but the sound is less irritating for some reason.

Capping the PTO side opening and forcing a front outlet can help as well.

Trying to create a quieter muffler that still flows is gonna be the next experimentation for me in saw porting. Flowmaster seems to have done a lot of baffle experimentation. I'll likely follow their leads.

 

[XP_Slinger]

I don't think there's sound wave scavenging happening in these little box mufflers the way it happens in a tuner pipe, at least not at a functional level. The shape is just not conducive to reflecting sound back to the port. What I do think is back pressure is playing a role in how much fuel is let out of the exhaust port before it closes. I should have clarified in my earlier post when I said I left the front of the muffler alone for reflection. What I meant by that is resistance to create back pressure. I think a muffler is working to its potential if there's no fuel getting spit out the outlet but fresh charge is making it into the muffler a little. And obviously with some of Mikes examples my theory gets blown out of the water. But on a work saw, I don't want a front port an inch from the log blasting exhaust off of it and subsequently in muh face. My theories aside I haven't really experimented with different muffler mods to find the balance between size and gain, given carb size, timing etc. A lot of guess work and assumptions from this guy.

 

[mdavlee]

The deeper the pipe goes into the muffler can the quieter they are.

 

[mdavlee]

The big front muffler has been good for another 10% over the others in a cant

 

[Deets066]

I cut them on an angle and fit them to the outside. Gives a larger opening at the muffler shell

 

[Deets066]

Anymore I just use a Red97 deflector

 

[XP_Slinger]

I make my own now, they're 288 deflector size

 

[mdavlee]

I use Red97 deflectors if they fit. If not I'll make my own.

 

[XP_Slinger]

Yeah I was bored one day and decided it couldn't be that difficult to make a die to make deflectors in my press. It's crude looking but it works pretty well. I'll be making more of various sizes to accommodate different saws where clearances are tight or there's lots of room for bigger deflectors.

 

[Deets066]

Anything I've done with a side outlet and a flat front had made the same power and less noise.

I did buy Stainless measuring/sauce cups of varying sizes off of amazon to try in mufflers, but they won't ever be able to reflect back what a tube with an expansion chamber can.

Next for me is to cap the inside part of my outlets inside the muffler to prevent any of the exhaust from escaping the openings directly. Kinda custom baffling.

The more the exhaust pulse swirls, the more random sound wave canceling effect occurs.

Like Mason said, the volume can sometimes be close, but the sound is less irritating for some reason.

Capping the PTO side opening and forcing a front outlet can help as well.

Trying to create a quieter muffler that still flows is gonna be the next experimentation for me in saw porting. Flowmaster seems to have done a lot of baffle experimentation. I'll likely follow their leads.

If you want to try something you could put a cone from just around the ex port widening out to the sides. Then an opposing cone on the front cover. Then two side ports

 

[Deets066]

I've thought of this for a while but never tried it

 

[Deets066]

If you want to try something you could put a cone from just around the ex port widening out to the sides. Then an opposing cone on the front cover. Then two side ports

 

[Deets066]

I'm sure it wouldn't flow quite like that but it's just an idea