ported 661 baffle in muffler vs baffle out

[Brewz]

When we say "baffle" are we talking the open thing that is just a couple bits of metal down the sides?

 

[Brewz]

It's my understanding and experience that a chainsaw does not need back pressure to make power. Any testing I've done/read shows that the more open the exhaust is, the more power you'll make. Going to extremes may result in useability issues, but not less power. These simple little saws don't have a tuned pipe. However, there quickly comes a point of diminishing returns. 10 years or so ago, Brian, aka Timberwolf, carefully documented this. My experience and testing shows the same. Personally, I've become more of a minimalist when it comes to a muffler mod. Sure, a more open muffler may make more power, but they quickly get too loud. Balance is the key.

I am going to agree with this on the saws I have built.
I am still a learner compared to others but on all the saws I have built, opening the muffler gains fairly quickly, and then just gets louder and then starts making tuning a bugger.
I too have gone back to conservative with exhaust openings but I still find no baffle runs best.

 

[paragonbuilder]

It's my understanding and experience that a chainsaw does not need back pressure to make power. Any testing I've done/read shows that the more open the exhaust is, the more power you'll make. Going to extremes may result in useability issues, but not less power. These simple little saws don't have a tuned pipe. However, there quickly comes a point of diminishing returns. 10 years or so ago, Brian, aka Timberwolf, carefully documented this. My experience and testing shows the same. Personally, I've become more of a minimalist when it comes to a muffler mod. Sure, a more open muffler may make more power, but they quickly get too loud. Balance is the key.

The only thing I've heard different is how Jason ports his saws now, he says too much muffler opening hurts them. His old way the bigger the better.
@jmssaws, can you elaborate on this?

 

[Brewz]

Is this the baffle in question?

 

[blsnelling]

Yes. You wouldn't think by looking at it that it would make any difference, but it does.

 

[blsnelling]

Tip of the day: Use a small end mill to drill out the spot welds, at least to finish them up.

 

[X 66 stang347 X]

I normally drill the spot welds it'll pop right out

 

[mdavlee]

I leave the brace in and open up the front and the side towards the original outlet.

 

[jmssaws]

I never take the baffle out either

 

[MustangMike]

On my unported 066 I just drilled a 1/2" hole through the baffle straight away, and then some much smaller holes on the side of the muff cover, adding a deflector on the left side. Seems to run real well for stock. Not super fast, but lots of grunt.

Regarding compression, in general the more you can compress the air/fuel mixture w/o detonation, the more power you will produce. As with everything, there is a point of diminishing returns, and the best ratio will depend on your fuel, combustion chamber design, and muffler venting to expel the heat.

Regarding muffler venting, unfortunately we are always driving blind on this one, but every engine will generate a pulse of flow at a certain RPM, and if you are lucky enough to find the right opening to correspond with that flow pulse, your saw will run better than if you don't. How the saw is ported, etc., will influence this a lot. Higher RPMs and compression will generally require more opening.

An over vented muffler will likely just result in an inefficient saw that expels unburned air/fuel.

The expansion of combusted fuel is tremendous, generally around 10:1.

 

[jmssaws]

The only thing I've heard different is how Jason ports his saws now, he says too much muffler opening hurts them. His old way the bigger the better.
@jmssaws, can you elaborate on this?

If you port the cylinder far enough you eventually you have a cylinder that will outflow everything around it,bigger carb didn't seem to help but less muffler outlet fixed it.

The way the muffler is when you get a saw from me is the way it has to be,pull the screen and kill it.

My 066 that Shaun ported was that way,it is a beast but pull either screen and you will notice it loose power and pick up idle trouble.
I put a 1" wb on it with a 880 boot and it didn't run one bit different.
The cylinder is simply maxed out.
You have ran that saw dan.
You have ran the unicorn and it's no different.
Pull the screen on it and you will hurt it.

 

[MustangMike]

I never take the baffle out either

Do you modify it?

 

[jmssaws]

Do you modify it?

Not on a 661.

I will say that a 661 is the only saw I port that the bigger the better on outlet but I got different things going on in it.

 

[MustangMike]

I was referring ot 066/660s???

 

[Mastermind]

It's my understanding and experience that a chainsaw does not need back pressure to make power. Any testing I've done/read shows that the more open the exhaust is, the more power you'll make. Going to extremes may result in useability issues, but not less power. These simple little saws don't have a tuned pipe. However, there quickly comes a point of diminishing returns. 10 years or so ago, Brian, aka Timberwolf, carefully documented this. My experience and testing shows the same. Personally, I've become more of a minimalist when it comes to a muffler mod. Sure, a more open muffler may make more power, but they quickly get too loud. Balance is the key.

Loud saws annoy me these days.

 

[MustangMike]

I figured putting some holes to vent to the sides like the 660 baffle.

Looks very similar to what I did with my unported 066, but my hole was 1/2", is that 7/16"???

 

[MustangMike]

Also, I've started leaving 460/461 baffles un molested, and have even thought of putting one on a 044/440.

Anyone have thoughts on this or any experience with it?

 

[Brewz]

If you port the cylinder far enough you eventually you have a cylinder that will outflow everything around it,bigger carb didn't seem to help but less muffler outlet fixed it.

The way the muffler is when you get a saw from me is the way it has to be,pull the screen and kill it.

My 066 that Shaun ported was that way,it is a beast but pull either screen and you will notice it loose power and pick up idle trouble.
I put a 1" wb on it with a 880 boot and it didn't run one bit different.
The cylinder is simply maxed out.
You have ran that saw dan.
You have ran the unicorn and it's no different.
Pull the screen on it and you will hurt it.

So basically, you guys have hit, and/or pushed past the limitations of the 1122 cylinder and use muffler restriction to keep it on par.
Hope to hit that point one day myself

 

[jmssaws]

Loud saws annoy me these days.

I run stock saws when I need to use one

 

[Brewz]

I run stock saws when I need to use one