DeadSkunk  (Warren)
DeadSkunk (Warren) PowerDork
2/23/21 12:51 p.m.

If I type "mufflers" into FB Marketplace or Craigslist I'll get a bunch of Harley mufflers showing up, and they're dirt cheap. Part of me wants to spend twenty bucks and fit one to my Miata or my son's Fiat 500 , just for gits and shiggles. Now to my question......why is it that one muffler of the pair has a much larger inlet than the other. I've never looked, but wouldn't there be one muffler for each cylinder and they'd be the same size?

aircooled
aircooled MegaDork
2/23/21 12:56 p.m.

That sounds like one of those code words they use for something else so the casual person (or filter) doesn't realize what they are actually selling.   

"Harley Muffler"  Clearly that is something almost no one actually buys... so I suspect they are actually selling meth.

 

(sorry) cheeky

Curtis73 (Forum Supporter)
Curtis73 (Forum Supporter) MegaDork
2/23/21 1:08 p.m.

It depends on the Harley, but many of them have a 2-1-2 exhaust.  The different sizes helps to tune the exhaust sound.

Apexcarver
Apexcarver UltimaDork
2/23/21 1:18 p.m.

Consider the power level of the harley motor you are pulling a muffler from, it will help indicate if it will flow enough.

 

Looked at one for my 65hp bugeye sprite, but I think you would be pushing it for even a miata...

wawazat
wawazat Dork
2/23/21 2:12 p.m.

Some of the baggers used a dummy exhaust on one side.  That may explain the different tube sizes.

Robbie (Forum Supporter)
Robbie (Forum Supporter) MegaDork
2/23/21 2:14 p.m.

I just scrapped a few motorcycle mufflers, wish I'd known you were looking. 

¯\_(ツ)_/¯
¯\_(ツ)_/¯ PowerDork
2/23/21 2:15 p.m.

As noted, a low rpm aircooled engine may not have a muffler that flows a lot.  That said, I've successfully used 1000cc+ sportbike mufflers on multiple cars without issue.

lateapexer
lateapexer Reader
2/23/21 2:22 p.m.

I used BSA and Triumph mufflers on various Minis. There was a lot of noise involved, I suspect not much change in performance. 

jfryjfry (FS)
jfryjfry (FS) Dork
2/23/21 2:51 p.m.

It's not how much power the engine makes, it's how much can it flow.  4-cylinder sport bikes have one muffler while twins usually have two.  Because for every exhaust pulse, the twin is pushing twice as much air. 
so a single twin muffler, for simplicity's sake, could be used up to about a 2000cc four cylinder. 
 

at least that was what I read, years ago....

DeadSkunk  (Warren)
DeadSkunk (Warren) PowerDork
2/23/21 3:01 p.m.

I think Curtis has it. I looked around for some pictures of a Road Glide and it appears tofit what he said. Here's the $20 mufflers, just to show the size difference.

May be an image of hair dryer

I think the bigger one would handle the flow of a small engine, but given that they aren't exactly quiet on a Road Glide, I have to wonder if I'd have much difference from a straight pipe. Maybe I should buy 8 of them to use one per cylinder on the Challenge Corolla's LS. cheeky

Vajingo
Vajingo Reader
2/23/21 5:45 p.m.

Wait... is someone actually going to try that hairbrained idea I suggested earlier?!?!? For the love of god man, it was a pipe dream!!! 

Curtis73 (Forum Supporter)
Curtis73 (Forum Supporter) MegaDork
2/23/21 7:04 p.m.
Vajingo said:

 For the love of god man, it was a pipe dream!!! 

literally.

codrus (Forum Supporter)
codrus (Forum Supporter) PowerDork
2/23/21 7:07 p.m.
jfryjfry (FS) said:

It's not how much power the engine makes, it's how much can it flow.

To a first approximation the two are the same.  More air => more fuel => more power.

 

Curtis73 (Forum Supporter)
Curtis73 (Forum Supporter) MegaDork
2/23/21 7:14 p.m.
DeadSkunk (Warren) said:

I think Curtis has it. I looked around for some pictures of a Road Glide and it appears tofit what he said. Here's the $20 mufflers, just to show the size difference.

May be an image of hair dryer

I think the bigger one would handle the flow of a small engine, but given that they aren't exactly quiet on a Road Glide, I have to wonder if I'd have much difference from a straight pipe. Maybe I should buy 8 of them to use one per cylinder on the Challenge Corolla's LS. cheeky

There was a similar (in function) setup that many companies did for F-body cat-back exhausts.  Many of them were configured like this:

The right tailpipe was just open to a shared first chamber in the muffler, so it got next to zero muffling, while the left tailpipe had to exit through the baffles of the muffler.  The resulting mix was how they achieved a unique sound they could put with their brand.

 

buzzboy
buzzboy Dork
2/24/21 9:44 a.m.

Harleys have mufflers?

Datsun310Guy
Datsun310Guy MegaDork
2/24/21 10:03 a.m.
buzzboy said:

Harleys have mufflers?

The Harley guys are all shrugging their shoulders and saying they don't know what you're asking.  

¯\_(ツ)_/¯
¯\_(ツ)_/¯ PowerDork
2/24/21 10:09 a.m.

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