ported 661 baffle in muffler vs baffle out

[MustangMike]

Even if you don't go backwards you may hit a point of diminishing returns, or as I've heard Randy put it "your just making more noise".

And although it was not tested, at that point I believe fuel efficiency will also start to suffer, which is an important factor to anyone who cuts for a living.

Unfortunately, I think the only method we have is testing and trial and error for each saw.

I also have a ported Asian 660 that seemed to like the baffle when it was first built, but then ran better w/o the baffle after it was broken in. Likely it picked up a few RPMs and that made the difference.

I think most of the builders figure out what works for their style of porting and stick with it. In general, ported saws will benefit from less restrictions.

 

[CR888]

I've always wanted to make a variable outlet size test muffler with some kind of slide that can be slid open/closed to change the exit port size. It would be easy to make if you were Scarr, Moparmyway, Kunz or Deetz. It would give you good basic data. But it appears there might be a few other factors like dual ports, pipe style, baffle and exit location that have their possible effects to also consider. Interesting though, even Stihl themselves demonstrated the importance of outlet area when the Aussie delivered MS660's came with factory dual ports, the small HP increase was significant. My 200t is a different saw simply by removing the spark screen.

 

[MustangMike]

Good point. I think all of the TM saws have screened ports, which likely reduce flow by about 50% and should be considered by anyone running unscreened ports (the AM mufflers often don't have screens). Yet, the 461 in the first video still seemed to hit a point of diminishing returns.

I've also wondered if 2 ports on one side work as well as two ports (one on each side). Also, the difference of moving the port front to back.

So many things to consider … guess that is what keeps it interesting!

 

[MustangMike]

I've also wondered what would happen if you put a 460/461 baffle in a 044/440? They did not come with that baffle (in the US).

If it added torque to a 460/461, why would it not for a 440???

 

[huskyboy]

I've also wondered what would happen if you put a 460/461 baffle in a 044/440? They did not come with that baffle (in the US).

If it added torque to a 460/461, why would it not for a 440???

I experimented with a 440. Stock cylinder with squish set at .020, first... tri port muffler no screens: saw idled erratically and it was hard to set the L side tune. Held good rpm in the cut but seemed to have a defined stalling point where it just stopped when leaning on it. Next: I put a flat muffler cover on it, keeping the dual side outlets. Saw idled and tuned noticeably better on the L side, but still a little touchy. Saw was more forgiving in the cut and sound was less obnoxious. Fuel economy seemed to improve a little. Next, I “woods ported” the saw. Which consisted of widening the ports, removing the large casting lip in the intake port/lower transfers, leveling the upper transfers as they were off left to right and mild timing advance. Saw tuned much easier. Erratic idling gone. Torque dramatically improved in the cut, you could lug the saw now. Cut times were faster. I think that a lot of the tuning and erratic running issues were mostly due to the lip on the intake port, but the muffler outlet definitely seemed to have an effect on how the saw ran.

 

[MustangMike]

When I played with the exhaust on my Brother's 460 it did not like it till I gave it a timing advance, then it was OK!

Still think it would be interesting to try a 440 with a 460/461 style baffle.

 

[Armbru84]

Bump.

 

[00wyk]

Even if you don't go backwards you may hit a point of diminishing returns, or as I've heard Randy put it "your just making more noise".

I opened the DP muffler on my ported 044 gradually. It kept making more and more power until I decided it was making enough noise.
If I were working in residential areas, I would have stopped much sooner.

It has plenty of grunt to pull a 30" bar in hardwoods, which I mostly use my 288 for, really.

 

[00wyk]

Here's the noise the thing makes at :92 secs in:

It's a bit loud...

 

[CR888]

I'm not saying power don't increase by opening mufflers but I find it hard to believe folks can so easily quantify small HP gains by running their saws in wood. Many have been fooled in the motorbike world when they buy an AM pipe that is a lot louder and feel like they are going faster only to realise they have increased their lap times. We are poor judges of small HP changes where as the stop watch don't lie. For saws I take to work I've gone a bit soft on overly loud saws.

 

[MustangMike]

I agree with you that judging how fast a saw cuts is best done with videoed timed cuts with the same B+C. However, other things (at least to me) are more easily felt. That said you have to have consistent chain, as sharpness and raker depth can make a huge difference.

I like to be a little heavy handed, so if a saw is lacking torque, or if it is high strung and easily stops in the cut, I'll notice it.

The baffle made a huge difference in the Asian / Cross 660. Even though that jug had pretty good port work, it much preferred a partial baffle.

 

[RI Chevy]

No need to be heavy handed with the saw Mike. I think you know that.
File the chain and let the saw power and chain do the work for you. Safer, better, more efficient.

 

[MustangMike]

Jeff, I keep my chains sharp and even my "AM bars" hold up fine, so I'm not too bad on them, just a little heavier handed than most … they cut faster that way, bigger chips!

 

[RI Chevy]

Then you have to lower your rakers a bit. You shouldn't have to lean on a bar as much as you do to get the saw to cut. SELF FEEDING is key.
Just trying to help. Not picking on you.

 

[MustangMike]

I self feed it a little faster!

 

[RI Chevy]

Not good though Mike. You know that. Throw away your gauges, take a couple swipes off each raker and retest. Until you can get a good self feeding chain that you do not have to lean on.
TRY SOMETHING DIFFERENT!!!!

 

[Moparmyway]

With these mufflers, partial load, full throttle, & proper tune; it’s going to be popping.

 

[RI Chevy]

Nice Kevin!
Now tighten your chain up please. Lol
Love the muffler sound

 

[Moparmyway]

Love the muffler sound

Did/do you hear the popping/miss/stumbling ?
Theres 4 stages to that cut in the video

1. Start of the cut, you hear it
2. After she loads up a little she runs clean
3. I push down real hard, no dogs, she runs clean
4. I ease up near the end of the cut, as she unloads and she stumbles alot

 

[huskyboy]

It doesn’t sound like timing related... as then it would do it even under load all the time. My ported 562 is on it’s 14,700 rev limiter (according to my tach) as soon as you lift or if you try cutting small wood like that with a slightly dull chain. It has a more tame muffler mod than Kevin’s saw. Rev boost makes them hit the limiter real fast and hard when limbing as well, I noticed 550’s do it too. The rev limiter is even more aggressive imo and at a lower rpm on the 572xp, 462 and 661 than the 550/562. I think there doing it on purpose to keep the cranks alive longer. Durability.