Cerberus
Cerberus the aardvark, not the hell-hound!!
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- 9:56 PM
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- 11523
- Joined
- Jan 20, 2020
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- Location
- Florida (tampa area)
tl;dr-- Seeking any&all data, insight, #'s, anecdotes, guesses & speculation(please be clear it is that, though!), on optimization of modding an OEM 660 muffler. I'm speaking of everything from exit hole placement to exit hole size to changes to the front-plate (or even its absence) hell even inclusion of baffle-plates sandwiched although so far as I know I'm the only one I've seen messing with that. Thanks in advance for any insight, the more specific the better!
[I'm happy even for generalities of any findings of this "minutiae type" of stuff, would pay for a link to the actual original content, my google-fu couldn't get me there I promise I tried!]
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I've now seen multiple anecdotes about some older testing/trials/works done on 066/660 mufflers, seems it was an OPE effort if it didn't occur on this site itself, and I am pretty sure @tree monkey was among/the leader/spaerheaded the effort (though based on context & chgronology I have to imagine MM & others were right alongside)
If anyone could point me to that thread it would be greatly appreciated, however as stated anything is appreciated, I know some, maybe all, will see this as dumb & that's just fine, I enjoy working my 660's and sadly I just know that going from my "really good" modded 660-cans, to "an optimum", it's not going to be that big a difference, nothing I could discern from test-cut measurements., so *gotta* be sure the theory/approach is fully on-point so I can hopefully have the testing not outright-contradict it (ie I'll test before/after, of course, I just don't expect to see anythign comparing my current OEM-modded-muff, to a "perfectly done" one..but still want to make a perfect one!)
SO, specifics:
- The 1 objective take-away I've found seems to be that, exit-hole sizing aside, that location matters (duh) and that the front-plate is a bad spot on the 660 muff. This seems like a "duh" thing to me, but I cannot reconcile it against something like the existence&popularity of the WCS "Bark Box" frontplate, thing looks neat but it's basically an open-hole for your exhaust pulse, meaning the return-pulse will automatically have atmosphere (and dilute your next powerstroke's incoming charge) So if front-plate holes are bad:
- How could Donny Walker, John's Custom Saws and other big-time builders use these plates? I can't figure this out it seems impossible they'd support them, but they do...
- Where, then, is/are the ideal location for muffler exit? On the 660 layout, for instance, I basically like to have exits "on the same plane" as Stihl's largest/primary exit hole (I suspect that lil fish gill exit on top of front-cover is simply a pressure-bleed to reduce intensity of the return-wave after the exhaust has opened/pulsed
Thanks a ton for any insight, thoughts/ideas anything, just has to be based around the 660 oem-style layout "as its skeleton", I've actually been working with "baffle plates" sandwiched in these mufflers to great successs am gonna make 1 more before showing it all in 1 of the muffler threads & the exhaust Megathread, but here it's 660 specific and jeepers I found videos showing how you can add a 2nd, 3rd opening to the rear belly and, nicely, the power keeps rising--- but they don't finish, by finding the point where power starts decreasing, and only knowing that lets you set it right-before that, which is the optimal!
(PS-- What of muffler "internal volume"? I ask because I'm contemplating using a steel-plate to seal the front insetad of the protruding OEM frontplate, this is for reasons of case-overhang (primarily) on a saw using a "header"/Grunt Gasket that's moving the muff forwards almost 1")
[I'm happy even for generalities of any findings of this "minutiae type" of stuff, would pay for a link to the actual original content, my google-fu couldn't get me there I promise I tried!]
~~~~~~~~~~~~
\
I've now seen multiple anecdotes about some older testing/trials/works done on 066/660 mufflers, seems it was an OPE effort if it didn't occur on this site itself, and I am pretty sure @tree monkey was among/the leader/spaerheaded the effort (though based on context & chgronology I have to imagine MM & others were right alongside)
If anyone could point me to that thread it would be greatly appreciated, however as stated anything is appreciated, I know some, maybe all, will see this as dumb & that's just fine, I enjoy working my 660's and sadly I just know that going from my "really good" modded 660-cans, to "an optimum", it's not going to be that big a difference, nothing I could discern from test-cut measurements., so *gotta* be sure the theory/approach is fully on-point so I can hopefully have the testing not outright-contradict it (ie I'll test before/after, of course, I just don't expect to see anythign comparing my current OEM-modded-muff, to a "perfectly done" one..but still want to make a perfect one!)
SO, specifics:
- The 1 objective take-away I've found seems to be that, exit-hole sizing aside, that location matters (duh) and that the front-plate is a bad spot on the 660 muff. This seems like a "duh" thing to me, but I cannot reconcile it against something like the existence&popularity of the WCS "Bark Box" frontplate, thing looks neat but it's basically an open-hole for your exhaust pulse, meaning the return-pulse will automatically have atmosphere (and dilute your next powerstroke's incoming charge) So if front-plate holes are bad:
- How could Donny Walker, John's Custom Saws and other big-time builders use these plates? I can't figure this out it seems impossible they'd support them, but they do...
- Where, then, is/are the ideal location for muffler exit? On the 660 layout, for instance, I basically like to have exits "on the same plane" as Stihl's largest/primary exit hole (I suspect that lil fish gill exit on top of front-cover is simply a pressure-bleed to reduce intensity of the return-wave after the exhaust has opened/pulsed
Thanks a ton for any insight, thoughts/ideas anything, just has to be based around the 660 oem-style layout "as its skeleton", I've actually been working with "baffle plates" sandwiched in these mufflers to great successs am gonna make 1 more before showing it all in 1 of the muffler threads & the exhaust Megathread, but here it's 660 specific and jeepers I found videos showing how you can add a 2nd, 3rd opening to the rear belly and, nicely, the power keeps rising--- but they don't finish, by finding the point where power starts decreasing, and only knowing that lets you set it right-before that, which is the optimal!
(PS-- What of muffler "internal volume"? I ask because I'm contemplating using a steel-plate to seal the front insetad of the protruding OEM frontplate, this is for reasons of case-overhang (primarily) on a saw using a "header"/Grunt Gasket that's moving the muff forwards almost 1")
