muffler mod engineering?

[borat]

B - you could have at least combed yer hair - Put your girl back up please

luck,greg

Just wanted to let you see how I managed to attract such a good looking girl.

Like my ma used to say, it pays to be good looking if you're not too smart.

 

[one.man.band]

openfoam.......

Just to show some simple and quick 2d calculations using a 0.6" inlet and a 0.75" outlet, and a very simple representation of a muffler.
the first picture is the pressure contour... someone correct me if i'm wrong, but i think i recall a lower pressure drop = more flow (ie more velocity)
there are areas of low and high pressure...most notable is the highest pressure right above the outlet (which may be drastically reduced if there was a radius on that corner)

View attachment 261222

Next is the velocity vector profile, notice the correlation between the two images. the vectors are most helpful in showing the air's path through the can.
The calculations were done using the mass flow rate of air exiting the cylinder of an 026 operating at 10,500 rpms.. (0.0104400625 kg/s).

View attachment 261223

Kinda fun i guess to see inside of what's going on. Im sure there are much more accurate ways to model this, i only did this very quickly.
It may be possible to "reenact" TimberWolf's experiment just to validate the computer results...
is this very useful? probably not unless you work for a chainsaw company...
I personally still like the idea of going a little at a time to notice the changes and learn that way

since a couple of you guys mentioned the CFD software:

what can this software do, other than showing air velocity directions and high and low pressure points within the muffler?

-omb

 

[old-cat]

I like tubes, a single 1" sounds great on a 372.

One single 1" inside dia. 2" long pipe with 1/2" out the side of the hollow muffler, makes an AWESOME sound!!! STIHL MS 361

 

[parrisw]

One single 1" inside dia. 2" long pipe with 1/2" out the side of the hollow muffler, makes an AWESOME sound!!! STIHL MS 361

YEP! My 372 with it freakin sounds amazing!

 

[bikesandcars]

YEP! My 372 with it freakin sounds amazing!

can you please describe amazing a little?

Does the pipe have a trumpet type effect on the sound?

How is the power with th

Is it louder, same as stock, quieter..

 

[parrisw]

can you please describe amazing a little?

Does the pipe have a trumpet type effect on the sound?

How is the power with th

Is it louder, same as stock, quieter..

Well, you'd have to hear it, vids just don't do it justice. I have two 372's one with a very large opening with just a deflector and one with the 1" pipe, the one with the pipe has way less compression and I thought the other would sound better but it doesn't. It's got a more lumpy idle, it pops more, and just sounds much more racy.

Here is the one without the pipe. I think I'm going to change this one over to the pipe setup.

[video=youtube;cr3ZbiNA1Uw]http://www.youtube.com/watch?v=cr3ZbiNA1Uw[/video]

 

[parrisw]

Here is the one with the pipe.

[video=youtube;HfP8ArrHbc4]http://www.youtube.com/watch?v=HfP8ArrHbc4[/video]

 

[old-cat]

Even pulling the starter, before it even fires , you can hear the distinctive sound. Deep, beautiful MUSIC!!

 

[parrisw]

Even pulling the starter, before it even fires , you can hear the distinctive sound. Deep, beautiful MUSIC!!

yup