Skip the muffler all together

[sachsmo]

This is how I picture what the back pressure does.The pic was from another thread.

A tuned pipe and back pressure are two different animals altogether.

 

[Jacob J.]

It always puts a smile on my face.

But I just cut a truck load at a time, pretty fast I may add.

I'd be interested to see if it's anymore or less powerful without a muffler altogether.

 

[sachsmo]

Ancient Chinese secret Bro'.

 

[IthacaMan]

A tuned pipe and back pressure are two different animals altogether.

But basicly its about pushing the air fuel mix back into the cylinder. Should it matter if its a pipe or a muffler? Its still back pressure right?

 

[Jacob J.]

But basicly its about pushing the air fuel mix back into the cylinder. Should it matter if its a pipe or a muffler? Its still back pressure right?

The tuned pipe (if tuned properly) produces a pressure wave, which if timed correctly forces some of the unburnt fuel and gasses present in the exhaust back into the engine prior to compression of the next stroke.

The back pressure you get from a muffler is sort of a static, constant jack-hammer style energy that doesn't really "stuff" the engine like a tuned pipe.

 

[sachsmo]

 

[sachsmo]

I'd be interested to see if it's anymore or less powerful without a muffler altogether.

Well,

that would just be silly runnin' it without a muffler.

 

[tomdcoker]

Most of those were reed valve engines, no?

And did not turn the RPM"s of todays saws. Tom

 

[sachsmo]

I may be way off base here.

But it seems to me that the next best thing to a properly tuned pipe would be no back pressure at all?

 

[IthacaMan]

The tuned pipe (if tuned properly) produces a pressure wave, which if timed correctly forces some of the unburnt fuel and gasses present in the exhaust back into the engine prior to compression of the next stroke.

The back pressure you get from a muffler is sort of a static, constant jack-hammer style energy that doesn't really "stuff" the engine like a tuned pipe.

Ok,So then if a stock muff was opened to the 80% of the cylinder outlet then would less of the mix be burned and excape out the exhaust because of less back pressure? Or would the more flow because of the increased muff opening make up for this? I dont mean to sound like I am wanting to argue, I am interested in understanding this better.

 

[Jacob J.]

I may be way off base here.

But it seems to me that the next best thing to a properly tuned pipe would be no back pressure at all?

It depends on what kind of work you're doing. When I was cutting logs, my fastest saw ever was an 046 with a highly modified engine but a stock muffler. It wore a 34" bar most of the time cutting Conifers that averaged 20" to 70".

I've seen some fast, fast cookie cutters that only had a shell of a muffler. They generated so much heat though that they couldn't run more than 25 seconds without seizing.

 

[sachsmo]

Well shoot,

I better just put the cat muffler back on, that should keep her cooler.

Dunno JJ but that little 59cc runs better than most 70cc saws.

But I'm just a firewood cutter so your milage may vary.

 

[Jacob J.]

A catalytic muffler is a whole different ballgame...

 

[sachsmo]

Ill crawl back under my bridge.


SORRY

 

[cpr]

Ill crawl back under my bridge.


SORRY

Ahh, you're a Hoosier, you don't have any of significance to get under :hmm3grin2orange::hmm3grin2orange::hmm3grin2orange:.

That'll get the yoopers going :yoyo:!

 

[3000 FPS]

Right out the front runs just fine.

View attachment 269012View attachment 269013

 

[kmcinms]

Since this thread has actually brought out some discussion of 2 stroke exhaust tuning, I'll post this two stroke tuning guide for you guys to chew on for a while. It is old school, but all the tuning perimeters are still basically the same. Enjoy. And make sure you check out the #1 fan!!!!

Two Stroke Tuners Handbook

 

[stihlrookie]

Right out the front runs just fine.

Not to be rude or offend in anyway, but how is that right out the front? The deflector appears to send the exhaust 90 degrees out the front of the muffler. I am just curious.

 

[3000 FPS]

Not to be rude or offend in anyway, but how is that right out the front? The deflector appears to send the exhaust 90 degrees out the front of the muffler. I am just curious.

Ok right out the front with a 90 degree curve. It is not bouncing off the front and then exiting out the side. Oh and I always use spark arrestors on all my muff mods.

 

[Jacob J.]

Ok right out the front with a 90 degree curve. It is not bouncing off the front and then exiting out the side. Oh and I always use spark arrestors on all my muff mods.

There's plenty of saws with front-exit mufflers in production. What I was talking about are the guys that chop the whole front of the muffler out, past the point of diminishing returns. Because it's so loud, they think "it has to run better." One local logger ended up spending $200 on new mufflers after modifying his with a bar wrench and a hammer.