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BASIC MATH QUESTION? -- Goofy Mini-Muffler build.. (Read 245 times)

teabowl13

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Re: BASIC MATH QUESTION?
Reply #15 - 07/29/12 at 21:13:10

Here's a shot of where the other end of the MINI_MUFFLER fits into the exhaust tubing.
That connector piece is a 1.75" ID standard exhaust tailpipe piece; it has a 45 degree bend and a 45 degree slash cut at the end, which is why the connection looks a little funky, but I think it will look great once it's welded up...
After marking where the muffler sits inside the pipe, I drilled a whole mess of small holes into the pipe to allow more flow-through. I wasn't concerned about these having the exact amount of area since they are in the middle of the exhaust; (it's the holes at the very end that will determine total flow) so these are all about 1/8" but there are 17-20 or so of them.... more than enough to do the job, and hopefully these will break up and scramble the exhaust flow and have a good baffling effect.

MINI-MUFFLER-4.JPG

VINTAGE ROADSTER BUILD: http://suzukisavage.com/cgi-bin/YaBB.pl?num=1323582921

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teabowl13 Serious Thumper Offline SuzukiSavage.com Rocks! Posts: 535	Re: BASIC MATH QUESTION? Reply #16 - 07/29/12 at 21:16:01 Here's a view looking into the inlet end of the mini-muffler. It looks gigantic because of the close-up-ness of the photo, but that opening is only 3/4". You can see the screen that goes down inside the muffler; it's a 3/4" ID tube of perforated metal running through the middle of it...
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Boule’tard

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Re: BASIC MATH QUESTION?
Reply #17 - 07/29/12 at 21:17:40

Whell, ellipses? CHANGE THE PROBLEM on us why don't ya Grin

Ok <math hat on>
You drilled out 6 half-inch holes on a 45 degree angle. The area of an ellipse is pi times the short radius times the long radius. The short radius is half the diameter of your drill bit = .25in. The long radius is half of your bit diameter/cos45 = .354in. So the area of each hole is pi*.25*.354=0.278in^2. The total area you drilled out with the 6 holes is 1.67in^2. Hope that helps.

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teabowl13

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Re: BASIC MATH QUESTION? -- Goofy Mini-Muffler bui
Reply #18 - 07/29/12 at 21:41:20

OH!
You must assume I drilled an ACTUAL ELIPSE! Well... let me tell ya...
I drilled these out by hand, just holding the thing down on the workbench and going for it.
When I say ellipse, what I mean is... I drilled out very small pilot holes to get started, then drilled them out with the 1/4" bit... THEN... while holding the little bugger firmly down to the bench with the drill bit running, I slowly lowered the drill down at an angle which ovalled out the holes a bit.

There's no exact science or math involved in the actual drilling process, so at this point the math is really more hypothetical than anything; although I DO very much appreciate you geeks putting your thinking caps on for this one! (I kid... I kid...) Grin

At this point I think the math has gotten me close enough to what I am looking for, and now I just need to get the bike running and see how she works in real life and fine-tune it from there based on seat-of-the-pants feel, and whether or not it's completely deafening...

CHEERS!

VINTAGE ROADSTER BUILD: http://suzukisavage.com/cgi-bin/YaBB.pl?num=1323582921

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Boule’tard

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Re: BASIC MATH QUESTION? -- Goofy Mini-Muffler bui
Reply #19 - 07/29/12 at 22:14:00

I'm sure your drilling skills are as good as my math skills.

If you were shooting for the equivalent of a 1.5" diameter hole (1.76in²) then I'd say you've got that and then some.

The 3/4" hole gives you 0.44in² and the other 6 holes are 1.67in², totaling 2.11in²

So if there is a bottleneck, it is probably not at the end of your muffler.. time to bust out the earplugs Cheesy

That which can be destroyed by the truth should be. - P.C. Hodgell

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teabowl13

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Re: BASIC MATH QUESTION? -- Goofy Mini-Muffler bui
Reply #20 - 07/29/12 at 22:31:21

SORRY BOULETARD...
I mis-typed that last post (just corrected it....) those holes are 1/4", not 1/2" BIG DIFFERENCE!

Either way, like I said, I feel like I have room to play with it iin a few different ways if I need to; drilling the holes out larger, or adding more baffling inside the connector, or stuffing the muffler with steel wool, so I'm hoping I can tune it to my taste once it's running.

VINTAGE ROADSTER BUILD: http://suzukisavage.com/cgi-bin/YaBB.pl?num=1323582921

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John in Kalifornia Full Member Offline SuzukiSavage.com Rocks! Posts: 127	Re: BASIC MATH QUESTION? -- Goofy Mini-Muffler bui Reply #21 - 07/29/12 at 23:42:18 If it falls off you can always use one of these as a replacement. John in Kalifornia
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justin_o_guy2 Serious Thumper Offline What happened? Posts: 55279 East Texas, 1/2 dallas/la.	Re: BASIC MATH QUESTION? -- Goofy Mini-Muffler bui Reply #22 - 07/30/12 at 05:08:09 I like it,
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