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Post by wutzthedeal on Mar 13, 2013 16:02:00 GMT -5
If I've opened up my air flow and upjetted, exhaust would be the only thing left in the restriction formula (with unlimited CDI), right? I drilled three small holes in the rear of the muffler, right around the exhaust outlet, but I have read that inside these mufflers is a pipe shaped like an hourglass, and that that is where the real bottleneck is, which would make my drill holes meaningless. Does anybody know if the new Chinese scoots all have this muffler design? I don't have a machine shop where I could tear it apart but I could drill down in through the part of the muffler before the bottleneck.
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Post by millsc on Mar 13, 2013 16:17:46 GMT -5
My friend drilled down the center of the exhaust hole with a large long bit, it worked for him, i just bought a performance exhaust
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Post by wutzthedeal on Mar 13, 2013 18:39:42 GMT -5
My friend drilled down the center of the exhaust hole with a large long bit, it worked for him, i just bought a performance exhaust That's what I'm thinking about doing now; I'd like to go under the plate so I could still dampen some of the noise but that's about a 50 degree angle and I don't know if I'll have a bit long enough; may just have to go right through the side and possibly re-cover the external hole (allowing exhaust to spill out and be forced through those other 3 holes I drilled). |
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Post by prodigit on Mar 13, 2013 19:54:08 GMT -5
Just don't do anything on the pipe coming from the engine.
Performance exhausts are basically exhaust mufflers with a larger exit than regular pipes; which results also in more noise.
If you want most performance, then get rid of the muffler.
But any kind of muffler will bring back pressure. The trick is to find one that dampens the sound more, while reducing back pressure.
Make sure you don't drill a hole in a place where rain water could leak in. It's a recipe of a quickly rusted exhaust.
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Post by CopperDeer on Mar 13, 2013 20:41:23 GMT -5
I drilled 3 or 4 3/8" holes about 5" deep in the back of my muffler. With opening up the intake & upjetting it worked really well and wasn't that much louder.
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Post by alleyoop on Mar 13, 2013 20:57:34 GMT -5
The chamber wall is close to the INTAKE SIDE so you can get a long drill to drill through the chamber wall.
Alleyoop
Wuzthedeal let me know what is a chamber ball and I corrected the typo and added an explaination to clarify.
I said BALL OOPS, should of been Wall, but anywhos you really have to know how the chambers are built inside the muffler. All mufflers are not the same and have different configurations of chambers inside.
So if you drill through one wall it may end up going into a sealed sound chamber and the exhuast has no where to go. You really have to open it up and see what needs to be opened up to free up the exhaust out the tailpipe. Best is to just buy a straight through muffler and if it is to loud narrow the exit to create a little back pressure and quiet it down some.
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Post by wutzthedeal on Mar 13, 2013 21:45:32 GMT -5
The chamber ball is close to the INTAKE SIDE so you can get a long drill to drill through the chamber ball. Alleyoop I can't even find that on the Google; can you point the way, sire? |
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Post by woowilly on Mar 13, 2013 23:12:14 GMT -5
left sketch is what I found in my muffler when I cut it apart to gut it. The right side is rotated  degrees to better illustrate it without having one tube behind the other. The horizontal lines just inside the inlet reresents the catalytic converter honeycomb. Not shown is the reinforcing strips between the upper and lower tubes on both the left and right side. Also not shown is the thin layer of fiberglass and metal screen on the inside of the shell. ( it's not wire type screen, it's sheet metal with about the max number of 3/16 inch holes possible.) Attachments:
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Post by millsc on Mar 13, 2013 23:14:56 GMT -5
I dont weld so i just scraped the muffler and bought a performance exhaust, but don't get it without a big bore kit, it bottlenecks due to not enough backpressure from the small bore.
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Post by woowilly on Mar 13, 2013 23:18:41 GMT -5
Upper sketch, not left sketch...
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Post by wutzthedeal on Mar 14, 2013 1:43:04 GMT -5
What did you do to it, willy?
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Post by wutzthedeal on Mar 15, 2013 16:21:26 GMT -5
My friend drilled down the center of the exhaust hole with a large long bit, it worked for him, i just bought a performance exhaust Question; what did your friend gain by doing this and on what model/year? |
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Post by millsc on Mar 15, 2013 16:35:12 GMT -5
not sure it would work on a stock motor, he has a 100cc big bore kit
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Post by wutzthedeal on Mar 15, 2013 16:40:04 GMT -5
I think I know what I'll do; I'll just run it up the road with the exhaust loose or the whole muffler off. If it doesn't increase top end then, there would be no point in drilling anything.
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Post by millsc on Mar 15, 2013 16:47:17 GMT -5
dont do that could burn an exhaust valve
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..BAD TO THE BONE..
degrees to better illustrate it without having one tube behind the other. The horizontal lines just inside the inlet reresents the catalytic converter honeycomb. Not shown is the reinforcing strips between the upper and lower tubes on both the left and right side. Also not shown is the thin layer of fiberglass and metal screen on the inside of the shell. ( it's not wire type screen, it's sheet metal with about the max number of 3/16 inch holes possible.)