Muffler Mod Temperature and Noise test.

[Teewhy]

Hi,
After time spent skulking around on this site having my questions answered, I decided to create an account and get involved.

I recently got my hands on a Stihl 660 with a mind to milling and the occasional big tree.

Knowing how hard milling is on saws, and wanting to give mine the best chance at longevity, I’ve been looking at muffler mods and their benefits.

However I don’t just want to drill out the output and chop up the baffles and be done with it, I want to find out what difference it makes with running temperature and any change in sound.

I’ve also got a husky 560xp and 236 that I might do the same to, just out of curiosity.

And I want to put up all my results here to help the next guy who decides to have a stab at entry level saw modding.

So my question (finally), am I in the right place on this thread, or should I go somewhere else on here?
Sorry for the waffle

Thanks Lads

 

[TheWizard]

the 560 is auto tune, i personally wouldn't used it for milling. it was designed for felling & limbing (short fast cuts) I would stick to that with this saw.

 

[Teewhy]

the 560 is auto tune, i personally wouldn't used it for milling. it was designed for felling & limbing (short fast cuts) I would stick to that with this saw.

100% agreed, I’m only modding the 560xp and 236 out of curiosity for the temperature change, not for use on a mill.

 

[JIMG]

When you modify the 660 muffler for milling I would suggest you remember to pay attention to direction of exhaust also. The farther away from your face the better.
I have two mufflers for my 394, one for milling and one for bucking and stumping type work.
Also, hello and welcome.

 

[Teewhy]

When you modify the 660 muffler for milling I would suggest you remember to pay attention to direction of exhaust also. The farther away from your face the better.
I have two mufflers for my 394, one for milling and one for bucking and stumping type work.
Also, hello and welcome.

That’s an interesting point, which direction would you recommend?
Would down and outwards in relation to the saw be best? And would it be best to close up the old outlet and open up one larger outlet on the front?

Thanks for the welcome.

 

[JIMG]

Here is a pic of the beauty I hang on the saw for milling.



Here you can just see how the exhaust is aimed when on the saw and milling frame.
(Note the impeccably tidy workshop.)

 

[Teewhy]

Here is a pic of the beauty I hang on the saw for milling.

View attachment 427933

Here you can just see how the exhaust is aimed when on the saw and milling frame.
(Note the impeccably tidy workshop.)


View attachment 427934

Phew that is some rig

I see, so your outlet is toward the bar and downward, meaning that it’s pointing completely away from you when in the milling position.
Did you remove the whole baffle? And do the whole 75% of the inlet thing when choosing your outlet size?


To be fair, when is a productive workshop ever tidy? It looks like a sweet set up to me in there.

Thanks for taking to time to point me in the right direction.

 

[Moparmyway]

I went the opposite side.

To me, getting the exhaust up, out, and away was better than having the saw and especially my lungs sucking it in.

I blocked off the factory exhaust too

 

[Teewhy]

I went the opposite side.

To me, getting the exhaust up, out, and away was better than having the saw and especially my lungs sucking it in.

I blocked off the factory exhaust tooView attachment 428148View attachment 428149View attachment 428150View attachment 428151View attachment 428152

Looks like I’ve got some catching up to do, you lads have some serious machines.

I got a chance today to have the 660 apart for the first time and made a list of needed parts.
She’s in need of a few bits and only came back with 110psi on the comp tester, so I have some investigating to do.
Once I’m happy that everything is where it needs to be, I’ll be carving the muffler and opening it up.

But, I did fit some dogs which look the part, versus none at all.


There’s only a 22in bar on it at the moment but it’s on my list to change.

See @JIMG , my workshop is much worse than yours.

Thanks again to all weighing in.

 

[drf256]

I went the opposite side.

To me, getting the exhaust up, out, and away was better than having the saw and especially my lungs sucking it in.

I blocked off the factory exhaust tooView attachment 428148View attachment 428149View attachment 428150View attachment 428151View attachment 428152

@Moparmyway built both of my milling saws (395/3120) and his muffler exit works very well. Up and away from me. Only have to huff in wood dust now without exhaust.

 

[EFSM]

And I want to put up all my results here to help the next guy who decides to have a stab at entry level saw modding.

C'mon! We need to let others hone their butt dyno!

Actually a scientific approach like this is what advances our culture. Too many people go through school without learning the scientific method.

 

[Teewhy]

Evening Gentleman, well evening here anyways.

Apologies for the radio silence here, my house flooded and spare time has been limited as a result.
I have no idea whether anyone will see this post actually, I have no idea how this works

I’ve finally got a free day to hopefully get the data I’m after this Monday.
I’ve just ordered a 4 Channel thermocouple data logger, and I was hoping for input on placement of the probe ends on the 660.

A few thoughts I’ve had:
- I’ll be using wire to secure the tips, adhesive is obviously a no go with the massive temperatures
- With the air pulled in during running I’m expecting temperature dips due to airflow, so if on probe end could be somewhat shielded from that it would be good to get data without having to shut the saw off.
- I could cover the tips with foil or something similar to shield them from the airflow.

Any wisdom would be greatly appreciated.

I’m sure I’m forgetting something, but there we go.

Thanks Lads, hope all is well in your parts of the world.

 

[Nutball]

You might try getting the probe tip between the cylinder fins in a middle slot and up against the cylinder in line with the exhaust/clutch corner cylinder bolt. Perhaps a little wad of aluminum foil stuffed over it and an aluminum wire twist tied around the cylinder to hold it in place.

You should have a consistent warm-up time and method, and a consistent test run time.

 

[ferris]

Im in

 

[Teewhy]

Hi again,

Another question, along with temperature and sound level, I’d like to test chain speed, extra torque etc, to see just what I’ve gained through opening up the muffler.
I haven’t got access to logs large enough to bury a 22in bar in a meaningful way so I was wondering whether a full bar bore cut up the grain in a smaller log would be a worthy test?
I’d start it just to the centre of the nose sprocket then time it from there to the dogs, repeat 3 times and average.
With a fresh sharpen before and after the mod to keep things as fair and ‘scientific’ as possible.

Or is that the kind of test that is heavily swayed by wood condition and chain profile?

Any other ideas?

Thanks @Nutball for those suggestions, sounds like a plan.


Cheers

Ty