My fishtail exhaust project

MilwDave

MilwDave

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I said I’d document the fishtail exhaust modification project that I’ve commissioned a local fabricator to assist me with.

Here are a few pics of the inside of the mufflers after they were opened up.

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Our plan is to tie the inlet end to the outlet with a SS slip pipe that provides a direct route for the gasses to flow through the mufflers.
The mesh that makes up the internal resonator will be removed to avoid any chance of ticking or rattling. The fiberglass packing will be reinstalled around the slip pipe before the outer casing is welded shut to minimize any chance of resonance.
 

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MilwDave said:
I said I’d document the fishtail exhaust modification project that I’ve commissioned a local fabricator to assist me with.

Here are a few pics of the inside of the mufflers after they were opened up.

img_9283-jpeg.13142


View attachment 13143

Our plan is to tie the inlet end to the outlet with a SS slip pipe that provides a direct route for the gasses to flow through the mufflers.
The mesh that makes up the internal resonator will be removed to avoid any chance of ticking or rattling. The fiberglass packing will be reinstalled around the slip pipe before the outer casing is welded shut to minimize any chance of resonance.
Click to expand...
Another option is to slash cut the back end which opens up approximately 75% for better, deeper tone. The internals to the slash cut kept intact.
 

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MilwDave said:
I’m looking for the classic look of the fishtail design. It is more in line with the retro style I’m trying to maintain.
Click to expand...
Dave, you have an excellent project with quality work! We all have different ideas on what makes us happy. I have always been for the chopper look. Thanks for sharing, Tony
 
MilwDave said:
I said I’d document the fishtail exhaust modification project that I’ve commissioned a local fabricator to assist me with.

Here are a few pics of the inside of the mufflers after they were opened up.

img_9283-jpeg.13142


View attachment 13143

Our plan is to tie the inlet end to the outlet with a SS slip pipe that provides a direct route for the gasses to flow through the mufflers.
The mesh that makes up the internal resonator will be removed to avoid any chance of ticking or rattling. The fiberglass packing will be reinstalled around the slip pipe before the outer casing is welded shut to minimize any chance of resonance.
Click to expand...
Quite a lot going on in there
 
Ulrich said:
Oh hell ... you are going for 'straight through' ... I am really curious how that will sound!!!
Click to expand...
The head pipes are gutted, the flapper valves removed and all holes sealed. It will be one long straight pipe exiting the fishtail.
The long run will maintain torque. We’ll see how the tone comes out.
I have already experimented with open head pipes (with cats and open valves) and the time was a little raspy for my tastes so I inserted some short honeycomb baffles and it sounded great. So I’ll try them straight and if needed the baffles will slip into the end of the head pipes. But in theory at least, the longer pipes and the few bends should be a little more mellow than short straight pipes.
 
MilwDave said:
The head pipes are gutted, the flapper valves removed and all holes sealed. It will be one long straight pipe exiting the fishtail.
The long run will maintain torque. We’ll see how the tone comes out.
I have already experimented with open head pipes (with cats and open valves) and the time was a little raspy for my tastes so I inserted some short honeycomb baffles and it sounded great. So I’ll try them straight and if needed the baffles will slip into the end of the head pipes. But in theory at least, the longer pipes and the few bends should be a little more mellow than short straight pipes.
Click to expand...
Good thinking! ... yes very excited to see/hear the results !
 
Aa a person that might one day attempt this.... once santa brings me a tig welder, I must ask.... how did the guy weld the added pipe on the side without access? My best bush mechanics brain can't work out how I'd do that. I could only do a tight over lapping fit on that side and weld 200 degrees of the pipe....
 
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Noelpolar said:
Aa a person that might one day attempt this.... once santa brings me a tig welder, I must ask.... how did the guy weld the added pipe on the side without access? My best bush mechanics brain can't work out how I'd do that. I could only do a tight over lapping fit on that side and weld 200 degrees of the pipe....
Click to expand...
I am getting the pictures of the work. I’ll try and stop by on Thursday to take a closer look.
Here is what he texted me:
“I can only weld about half way on the inside one. But I tapered the pipe and hammered it on to seal it up as best as possible”
 
Hi MilwDave,
I must say I'm impressed with your passion for the project. The Akrapovic modification I shared here on the forum is simple by comparison.
I have three questions please. :)
1. Is the original mesh part completely hollow? And separated from the front and outlet part only by baffles?
2. The two holes in front of the outlet were presumably from the factory. I'm not sure why they were there, since they were apparently hidden under the heat wool? In your picture, I can see that you've welded them with a plate.
3. And do I understand correctly that you also removed the catalytic converters?
Fingers crossed that everything turns out to your satisfaction.🤞🤞🤞
 
Petr Kunc said:
Hi MilwDave,
I must say I'm impressed with your passion for the project. The Akrapovic modification I shared here on the forum is simple by comparison.
I have three questions please. :)
1. Is the original mesh part completely hollow? And separated from the front and outlet part only by baffles?
2. The two holes in front of the outlet were presumably from the factory. I'm not sure why they were there, since they were apparently hidden under the heat wool? In your picture, I can see that you've welded them with a plate.
3. And do I understand correctly that you also removed the catalytic converters?
Fingers crossed that everything turns out to your satisfaction.🤞🤞🤞
Click to expand...
The mesh structure is hollow inside and wrapped with a fiberglass blanket. No different than the typical motorcycle muffler packing.
While I’m not present at the site where the fabrication is being done, I would assume those two holes are to equalize the pressure inside the muffler. Since we are essentially making it a straight thru system, the fishtails are going to be acting as a large heat shield and nothing more.
The head pipes are complete. We removed the catalyst and the flapper assemblies, the holes are welded up.
When the job is complete the entire system will be ceramic coated a matte black.View attachment 13302View attachment 13303View attachment 13304
 

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MilwDave said:
The mesh structure is hollow inside and wrapped with a fiberglass blanket. No different than the typical motorcycle muffler packing.
While I’m not present at the site where the fabrication is being done, I would assume those two holes are to equalize the pressure inside the muffler. Since we are essentially making it a straight thru system, the fishtails are going to be acting as a large heat shield and nothing more.
The head pipes are complete. We removed the catalyst and the flapper assemblies, the holes are welded up.
When the job is complete the entire system will be ceramic coated a matte black.
Click to expand...
Thanks, and I'm curious to see how it turns out. Break a leg :)
 
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