Dual port vs single port muffler mod difference

[272super]

As far as muffler mods go, is there any science behind a dual port performing better than a single port with the same outlet volume? I noticed alot of Stihl's have the dual port oem muffler option so there must be some science behind it. Anyone care to offer any theories or is there really very little difference if any?

 

[Mastermind]

I normally do a single outlet.......sort of a "sleeper" look. Just because.......no science involved.

I do wonder if you are onto something though.

 

[moody]

I normally do a single outlet.......sort of a "sleeper" look. Just because.......no science involved.

I do wonder if you are onto something though.

I wonder if it has something to do with heat diverson. Instead of heat building up in a single location the dual port allows heat to disperse more evenly. Less heat allows for more power or you would at least think so.

 

[Arrowhead]

I would think a dual port would be better. Having 2 outlets should make the exhaust leave easier and quicker.
At least that's how it works in my feeble mind. :msp_unsure:

 

[moody]

I would think a dual port would be better. Having 2 outlets should make the exhaust leave easier and quicker.
At least that's how it works in my feeble mind. :msp_unsure:

Velocity test is needed:msp_thumbup:

 

[Nardoo]

opcorn:

 

[ozflea]

Partner P100 Super had a dual port option that way you could blow it either side or end

McBob

 

[chadihman]

My dual port on my 460 showed .7 hp gain vs the tiny holed oem muffler. I have a 460 muffler that has a single pipe mod. I guess I'll have to test it.

 

[anlrolfe]

Just because.......no science involved

?? Surely there is such a thing called "Harmonics" and "Resonance"??

I work mainly with electrical circuitry but the concepts used in AC filter circuits are close kin to intake and exhaust flow dynamics.

Circuit pipes cousin is a saxophone.

If you can tune a guitar you can tune-a-muffler.

 

[old-cat]

If dual port is better than single port, then quad port should be better still!:jester:

 

[stihl for life]

i have a mooded ms660 with a custom triple port muffler . i really find it sounds louder and cuts faster then my logging buddy's with a stander dp. with my understanding the engine has 4 cycles if im not correct . intake, compression, something i forget and exhaust.. between the exhaust/intake stroke .i believe the intake and exhaust port are open at the same time for a briefer period of time.so if you can eliminate exhaust faster allowing more intake giving the engine more fuel thus making more power.

 

[mt.stalker]

i have a mooded ms660 with a custom triple port muffler . i really find it sounds louder and cuts faster then my logging buddy's with a stander dp. with my understanding the engine has 4 cycles if im not correct . intake, compression, something i forget and exhaust.. between the exhaust/intake stroke .i believe the intake and exhaust port are open at the same time for a briefer period of time.so if you can eliminate exhaust faster allowing more intake giving the engine more fuel thus making more power.

You're thinking 4 cycle engine here . Intake , compression , power , exhaust . With a 2 cycle (chainsaw) engine , it's intake/exhaust on one cycle , and compression/power on the opposite cycle .

 

[stihl for life]

You're thinking 4 cycle engine here . Intake , compression , power , exhaust . With a 2 cycle (chainsaw) engine , it's intake/exhaust on one cycle , and compression/power on the opposite cycle .

yes you are right haha man I need to go back to school

 

[maico490]

Velocity test is needed:msp_thumbup:

Velocity is speed with a specified direction. How are you going to know you have got both measured correctly.:msp_unsure:

 

[Trx250r180]

tripple port is common with the fallers here with the 660 stihl , they sure sound good echoing through the trees :msp_wink:

 

[Mike from Maine]

Since gas flow through a pipe is faster in center than the edges wouldn't one hole be more efficient?

 

[harrygrey382]

Yes good point, friction. But would that be counteracted by other factors inside the muffler - like if the gas had to pass round other objects/restrictions and therefore would be easier to take simultaneous alternate routes? I'm not sure though.

My dual port on my 460 showed .7 hp gain vs the tiny holed oem muffler. I have a 460 muffler that has a single pipe mod. I guess I'll have to test it.

This is the definitive test obviously. But you need to make sure the cross sectional area of the total exit ports are the same for each

 

[Marius]

As far as muffler mods go, is there any science behind a dual port performing better than a single port with the same outlet volume? I noticed alot of Stihl's have the dual port oem muffler option so there must be some science behind it. Anyone care to offer any theories or is there really very little difference if any?

I do not understand the benefit of having two exhaust ports on a two stroke engine. One exhaust port 80 percent the size of the exhaust port on the cylinder has worked well for me. The idea is to get the exhaust can to simulate how an expansion pipe would work in the way a percentage of the exhaust sign wave is directed back into the exhaust port on the cylinder to pressurize the crankcase along with the downward stroke of the piston. Therefore scavenging more air fuel mixture from the intake charging the crankcase to increase air fuel thru the transfer ports into the combustion chamber increasing power as the rpms of the engine increase. Of which the height of the exhaust port has much to do with where in the rpm range you like power to be delivered. The higher the exhaust port the higher and narrower the powerband will be. To a certain point where you will start to lose power max aprox. 208 degrees that which I have never even seen come close to with a chain saw usually max 180 degrees or so. This is just my understanding on the subject seems to work for me but I am sure there are many other schools of thought on the subject that I would be very interested in learning about. I think I am only scratching the surface on the topic.

 

[buttercup]

As far as muffler mods go, is there any science behind a dual port performing better than a single port with the same outlet volume? I noticed alot of Stihl's have the dual port oem muffler option so there must be some science behind it. Anyone care to offer any theories or is there really very little difference if any?

Area is what matters (flowthrough), if you divide it into several outlets its about practical considerations.

https://www.arboristsite.com/community/threads/my-038-foolium-adventure.340536/
These 3 outlets have together the same area as a one 1" diameter outlet (72cc).
This particular muffler have a much larger outlet area than my Dolmar 7910, and at the same time a considerable and clearly notable softer (dull/numb) and more pleasant sound to it.
Sharp noises is what damages yours and your neighbors ears - permanently.

 

[pioneerguy600]

WOW!