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Sawrain

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Rescued a neglected 036, runs better than it looks.

Anyway decided to get some numbers on the MM.

Exhaust port, didn’t compensate for curvature. ‍
Calculated from app, 302mm^2
Calculated from 27x12mm, 324mm^2
e2d9b45e-294c-4876-9b3d-1271aa4eee1e-jpeg.213560


Muffler openings.
Main opening calculated from app, 315mm^2
Main opening calculated from, 17x21mm, 357mm^2

Calculated total with louvred opening, 358mm^2

3fc02385-7c06-4e2b-95c8-645232748e6a-jpeg.213562


Factory screen has openings,
0.55mm * 0.55mm = 0.303mm^2 each.
Mine has 30 * 36 openings.
1080 * 0.303 = 327mm^2
Could raise this to 380mm^2 with some more grinding to expose more screen, or use a different mesh.


15d49495-2d3b-424b-8297-53dffe1d422e-jpeg.213563


So stock exhaust port at piston,,. 302mm^2
Opened up muffler discharge,,,,. 358mm^2
Total combined screen opening,.327mm^2

Muffler discharge 118% of cylinder exhaust port, (150% looks achievable with more work)
Screen opening 108% of cylinder exhaust port, (125%+ achievable with stock mesh)

The main thing I would like to consider would be the discharge coefficient of the mesh, while it's openings equals 108% of the exhaust port, they may cause more restriction than this number shows due to they way the gasses pass through it.
 

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mdavlee

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Rescued a neglected 036, runs better than it looks.

Anyway decided to get some numbers on the MM.

Exhaust port, didn’t compensate for curvature. ‍
Calculated from app, 302mm^2
Calculated from 27x12mm, 324mm^2
e2d9b45e-294c-4876-9b3d-1271aa4eee1e-jpeg.213560


Muffler openings.
Main opening calculated from app, 315mm^2
Main opening calculated from, 17x21mm, 357mm^2

Calculated total with louvred opening, 358mm^2

3fc02385-7c06-4e2b-95c8-645232748e6a-jpeg.213562


Factory screen has openings,
0.55mm * 0.55mm = 0.303mm^2 each.
Mine has 30 * 36 openings.
1080 * 0.303 = 327mm^2
Could raise this to 380mm^2 with some more grinding to expose more screen, or use a different mesh.


15d49495-2d3b-424b-8297-53dffe1d422e-jpeg.213563


So stock exhaust port at piston,,. 302mm^2
Opened up muffler discharge,,,,. 358mm^2
Total combined screen opening,.327mm^2

Muffler discharge 118% of cylinder exhaust port, (150% looks achievable with more work)
Screen opening 108% of cylinder exhaust port, (125%+ achievable with stock mesh)

The main thing I would like to consider would be the discharge coefficient of the mesh, while it's openings equals 108% of the exhaust port, they may cause more restriction than this number shows due to they way the gasses pass through it.

Every edge has some flow disturbance compared to one big hole.
 

Ketchup

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Rescued a neglected 036, runs better than it looks.

Anyway decided to get some numbers on the MM.

Exhaust port, didn’t compensate for curvature. ‍
Calculated from app, 302mm^2
Calculated from 27x12mm, 324mm^2
e2d9b45e-294c-4876-9b3d-1271aa4eee1e-jpeg.213560


Muffler openings.
Main opening calculated from app, 315mm^2
Main opening calculated from, 17x21mm, 357mm^2

Calculated total with louvred opening, 358mm^2

3fc02385-7c06-4e2b-95c8-645232748e6a-jpeg.213562


Factory screen has openings,
0.55mm * 0.55mm = 0.303mm^2 each.
Mine has 30 * 36 openings.
1080 * 0.303 = 327mm^2
Could raise this to 380mm^2 with some more grinding to expose more screen, or use a different mesh.


15d49495-2d3b-424b-8297-53dffe1d422e-jpeg.213563


So stock exhaust port at piston,,. 302mm^2
Opened up muffler discharge,,,,. 358mm^2
Total combined screen opening,.327mm^2

Muffler discharge 118% of cylinder exhaust port, (150% looks achievable with more work)
Screen opening 108% of cylinder exhaust port, (125%+ achievable with stock mesh)

The main thing I would like to consider would be the discharge coefficient of the mesh, while it's openings equals 108% of the exhaust port, they may cause more restriction than this number shows due to they way the gasses pass through it.

That’s cool. What app are you using?
 

NPKenny

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Here’s one done out of necessity on a previously hacked-up muffler. A good bit of clean-up inside and a scrap piece of rectangular tubing cut to fit for a deflector. The screen is secure and pretty easy to clean / replace.

546C9330-C26E-43F4-B3D3-5D01740C48A7.jpeg 77172451-1D15-4084-8113-AEDABC7F9041.jpeg

E5CA36BD-FB0C-403D-8F09-547C91D1F836.jpeg
 

Moparmyway

Its just a saw
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My stumping/milling slut muffler mod

IMG_6448.JPG
7D0ED199-FBDB-4AD0-971D-5DF4B98901C2.jpeg
D9F0F8E0-FE92-4E3E-8F50-E319A5A72D96.jpeg



And this is what it looks like when milling or stumpingIMG_6440.JPG


The stock opening is closed with a piece of aluminum flashing, easily removed if I want to open it back upIMG_6443.JPG
 
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merc_man

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Agent Smith

Hack of all trades
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Just finished up this dual port muffler for the 026 project im working on. Welded up the factory outlet inside the cover
 

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Benwa

I love the smell of premix in the morning
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A little craftsman I did up for a buddy. Some of these have 2 very small louvers for an outlet, on the clutch side, in the rear upper corner of the muffler. They use the partition as the deflector. Nothing crazy, but should flow a little better now. 20200119_011638.jpg
20200119_011605.jpg
20200119_012929.jpg
 
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