Skip the muffler all together

[farmerdoug]

Has anyone ever tried skipping the muffler all together? A fire hazard is the only reason I could see a person not doing this. Wouldn't be an issue if you are cutting in the pouring rain.

 

[sgrizz]

No muffler = no back pressure which in the end makes no power.
plus you could burn the saw up with it running lean this way. Just my opinion .

 

[Anthony_Va.]

Not good to run without the muffler IMO. The backpressure is vital to the engine running good. Pretty sure it has something to do with scavenging.

Plus, lots of dirt and sawdust could fly into the cylinder through the exhaust port.

 

[husqvarnaguy]

It would run but not for long. This experiment was performed by trained profesionals. Do not under any circumstances try it at home.

 

[Plan-b]

Has anyone ever tried skipping the muffler all together? A fire hazard is the only reason I could see a person not doing this. Wouldn't be an issue if you are cutting in the pouring rain.

Have you ever seen a muffler mod with a big hole in the front with some screen over it?

Do you think that flows less then the open port?

I would say it's the same. The screen prevents the junk from falling in.

 

[farmerdoug]

Muffler Answer

So Basically The muffler keeps the engine clean on the exit along with some back pressure.

The air filter keeps the engine clean on the intake.

So a muffler mod is really a modification, not to be overdone to help increase air flow some, but not too much.

Too much restriction on the exit cuts out horse power, but no muffler at all would:

• Expose the engine to dirt
• Ruin the engine because of no back pressure

Let me know if what I am gathering is wrong - Thanks:msp_smile:

 

[CTYank]

Not good to run without the muffler IMO. The backpressure is vital to the engine running good. Pretty sure it has something to do with scavenging.

Plus, lots of dirt and sawdust could fly into the cylinder through the exhaust port.

McCulloch said exactly that in the manual of a 50 cc-ish saw from the '60s. Muffler on that saw was a short rectangular tube with cross-strips at discharge, not really muffling anything. Deafening.

Many "mufflers" back then provided zero back-pressure.

 

[cpr]

So Basically The muffler keeps the engine clean on the exit along with some back pressure.

The air filter keeps the engine clean on the intake.

So a muffler mod is really a modification, not to be overdone to help increase air flow some, but not too much.

Too much restriction on the exit cuts out horse power, but no muffler at all would:

• Expose the engine to dirt
• Ruin the engine because of no back pressure

Let me know if what I am gathering is wrong - Thanks:msp_smile:

You've got the basics. It has been tested and, generally, it will not work. There are, of course exceptions.

This saw is about as close to an open exhaust as you can get, but it is also fed by a carb that can move enough fuel to keep up.


View attachment 268969

 

[cpr]

BTW, Doug.

I've been pretty impressed at your willingness to jump in and work on saws, think about what you're doing, and ask questions.

 

[z71mike]

McCulloch said exactly that in the manual of a 50 cc-ish saw from the '60s. Muffler on that saw was a short rectangular tube with cross-strips at discharge, not really muffling anything. Deafening.

Many "mufflers" back then provided zero back-pressure.

Most of those were reed valve engines, no?

 

[Plan-b]

So Basically The muffler keeps the engine clean on the exit along with some back pressure.

The air filter keeps the engine clean on the intake.

So a muffler mod is really a modification, not to be overdone to help increase air flow some, but not too much.

Too much restriction on the exit cuts out horse power, but no muffler at all would:

• Expose the engine to dirt
• Ruin the engine because of no back pressure

Let me know if what I am gathering is wrong - Thanks:msp_smile:

You will not ruin the engine running without a muffler. (assuming the a/f mixture is correct) You lose efficency. Will use more fuel and make less power.

Think about it this way. When the piston is at BDC both the intake and exhaust ports are open, the intake charge is on the move threw the engine at this point, now the charge is also exiting threw the ext. port, a simple muffler (a square) just provides a wall for this charge to bounce back into the exhaust port.

This is why you see all mufflers with exit ports behind or to the side of the exhaust port. It gives it time to reflect back into the exhaust port before it leaves the muffler.

 

[cpr]

McCulloch said exactly that in the manual of a 50 cc-ish saw from the '60s. Muffler on that saw was a short rectangular tube with cross-strips at discharge, not really muffling anything. Deafening.

Many "mufflers" back then provided zero back-pressure.

Most of those were reed valve engines, no?

The cross-hatched stack pipes were on reed saws, yes. If I'm not mistaken, the dirt issue was in reference to why the early 54cc 10-10s had that reed muffler design, but the saw itself was piston ported.

 

[WidowMaker1]

Do not under any circumstances try it at home.

life would be dull & boring if the safe road was always taken.

 

[logging22]

Mufflers. PFTTTTTTT!!:rolleyes2:

 

[Jacob J.]

You will not ruin the engine running without a muffler. (assuming the a/f mixture is correct) You lose efficency. Will use more fuel and make less power.

Think about it this way. When the piston is at BDC both the intake and exhaust ports are open, the intake charge is on the move threw the engine at this point, now the charge is also exiting threw the ext. port, a simple muffler (a square) just provides a wall for this charge to bounce back into the exhaust port.

This is why you see all mufflers with exit ports behind or to the side of the exhaust port. It gives it time to reflect back into the exhaust port before it leaves the muffler.

I have yet to see a modern saw where both the intake and exhaust were open at the same time when the piston is at BDC. If you know of a modern saw with this design, I'd be interested in looking at it.

Backpressure is not a reason that running a modern without a muffler will do damage to the engine, heat is the reason. The muffler serves as a conduit for heat. The modern, high speed two-cycle design used in modern saws creates more heat in a shorter amount of time than those old reed-valve saws, and they run at almost double the RPM as those old dinosaurs. Some backpressure is needed yes, but a standard saw muffler is a not tuned pipe.

Yes, there are people (even on this site) who have put large holes in the front of the muffler allowing the exhaust to shoot straight out. However, in a working situation, those saws tend to have less torque and do less work in a day.

 

[sachsmo]

Hahahahahahaha,

 

[kmcinms]

Da^* winter is finally here

You boys have been punked once again by the farmer.....

 

[Jacob J.]

Hahahahahahaha

Oh yeah, I wanna run that all day...

 

[sachsmo]

Oh yeah, I wanna run that all day...

It always puts a smile on my face.

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

 

[IthacaMan]

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