ported 661 baffle in muffler vs baffle out

[Redbull661]

32:1 , eth free, 36" .404 RS new chains for both.

no baffle, Dual side ports, port on front cover
43.8 43.7 352F on jug

baffle , dual side ports, port on front cover. (note on the baffle - I already knew a baffled muffler would be slower+hotter, so on this baffle ,dremeled a bunch of 3/16" holes into it...so it almost looked like a 066/660 baffle...didn't change the results. Saw felt like it had less power/torque etc.
44.5, 44.9 380F on jug

 

[Armbru84]

Always great tests. Interesting to see the 10% temp difference.

 

[Four Paws]

Wonder what your results would be without a baffle and with the front cover removed?

 

[Deets066]

Wonder what your results would be without a baffle and with the front cover removed?

Results?

My guess is temporary loss of hearing

 

[Deets066]

32:1 , eth free, 36" .404 RS new chains for both.

no baffle, Dual side ports, port on front cover
43.8 43.7 352F on jug

baffle , dual side ports, port on front cover. (note on the baffle - I already knew a baffled muffler would be slower+hotter, so on this baffle ,dremeled a bunch of 3/16" holes into it...so it almost looked like a 066/660 baffle...didn't change the results. Saw felt like it had less power/torque etc.
44.5, 44.9 380F on jug

So have you finally decided to just chit can the baffle?

 

[ferris]

Regular carb?
Max rpm?

 

[drf256]

Looking good Julian.

Always love your data.

 

[Cigmaker]

Appreciate all these tests I'd never think of.

 

[Redbull661]

Wonder what your results would be without a baffle and with the front cover removed?

not a ported 661 but.. (muffler does not have a baffle in it) Listen to each saw as the nose end of the bar drops into the wood.

So have you finally decided to just chit can the baffle?

all the tests I've done point to, a baffle is going to hold too much heat in the saw. I think the same holds true for thin weave screens vs wider weave. So the key seems to be how large one makes the port or ports, which I think depends on how modded or un modded the saw is.

screens - got this from Randy...what he uses.

www.amazon.com/dp/B005H3C92W?tag=_&camp=14573&creative=327641&linkCode=as1&creativeASIN=B005H3C92W&adid=1NF40GZGHKMK7S67PEX9&


my attempt with the baffle in the 661 (which is already pretty open) was to fill it with holes and see if I could negate the heat issue and maybe gain some time with more back pressure if there is such a thing. Didn't work.

I think in a stock 661 all I would do is change the screen and take out the baffle. Port size could probably stay the same. On the flip side tree monkey 661 runs best with 2 large side ports and maybe or maybe not a port on the front.

Regular carb?
Max rpm?

mtronic. if I recall the rpm difference wasn't that much. Max rpm on that saw is around 13800-13900.

 

[Adirondackstihl]

Pics of muffler mods?

 

[blsnelling]

Hmmmmm

 

[Chainsaw Jim]

What about the temperature? Is 380 a better running temperature? I see close enough timed cuts to almost call even so it appears the expected gain from the removal of the baffle may have been effected by a lower running temp.

 

[drf256]

I'm betting a non-ported saw with less static compression makes more power hotter than the same saw ported.

 

[jmssaws]

I'm betting a non-ported saw with less static compression makes more power hotter than the same saw ported.

Interesting,how do we know for sure?

I think at some point your right but there has to be a happy place,ain't there?

 

[drf256]

Just saying heat plays a role. So does backpressure.

When we add compression, we are doing so to add heat to the combustion process.

A happy medium must exist.

What's so great about Julian's observations is that he tries to make the data as objective as possible.

 

[jmssaws]

I done some stock/ported cylinder temp testing a while back and really didn't see much difference, the ported cylinders open muffler seemed to level the feild some.

 

[jmssaws]

That was with one saw though and we all know what works on one might not on another one just like it.

 

[blsnelling]

I'm betting a non-ported saw with less static compression makes more power hotter than the same saw ported.

Makes sense to me. I think it's a mistake to just assume that cooler is always better. People serious about max performance use an EGT so that they can safely run closer to the edge of being to hot.

That being said, it's been proven before that the 661 runs better without the baffle.

 

[mdavlee]

Makes sense to me. I think it's a mistake to just assume that cooler is always better. People serious about max performance use an EGT so that they can safely run closer to the edge of being to hot.

That being said, it's been proven before that the 661 runs better without the baffle.

That is very true. I've always wanted to know max cylinder temps when milling a 8-10 minute cut. There's enough heat soak to boil bar oil. The only thing I had to check temperature was temp sticks for checking pre heat on pipe to weld. The highest I had was 550° and it melted instantly on the fins. It didn't hurt the P/C at that temperature.

 

[blsnelling]

Just saying heat plays a role. So does backpressure.

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.