Magnaflow 12578/12579
#41
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I suspect it is minimal.
This image is interesting. You can see where the inside edge of the perforated internal tube "disrupts" the flow into the side tubes. On my 1x579 muffler there was one end that looked like the above pic, and the other end was actually much better. It may just be manufacturing tolerance (or lack thereof) or simply luck of the draw. My muffler is oriented so that the "better" side is the "inlet" side. I'd like to think that'll help.
I considered getting in there with some sort of tool and cutting down those edges but its all stainless. It looked like it was going to be a bitch to do so I moved on to other things.
This image is interesting. You can see where the inside edge of the perforated internal tube "disrupts" the flow into the side tubes. On my 1x579 muffler there was one end that looked like the above pic, and the other end was actually much better. It may just be manufacturing tolerance (or lack thereof) or simply luck of the draw. My muffler is oriented so that the "better" side is the "inlet" side. I'd like to think that'll help.
I considered getting in there with some sort of tool and cutting down those edges but its all stainless. It looked like it was going to be a bitch to do so I moved on to other things.
#42
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Anyone have any idea how much horsepowers are lost with the 12578? My wife and I just took a trip to the Mitty in the Miata, Va. to Ga. We could'nt hear the radio, so we cut it off. The drone gave me a headache after a while. Would lie to fix that without loosing my horsee's.
#43
In fact, it looks almost exactly like this thing inside the muffler:
http://www.summitracing.com/parts/mpe-10778
And that's funny, because not only is it also made by Magnaflow, I also own that part as well, its part of the exhaust on my truck
http://www.summitracing.com/parts/mpe-10778
And that's funny, because not only is it also made by Magnaflow, I also own that part as well, its part of the exhaust on my truck
While much better than a simple expansion chamber, the flat instead of a 'V' will introduce some turbulence. It would be interesting to measure the actual muffler pressure loss. I measured mine some time ago, (3" straight through), and it was on the order of 1 psi including the bends before and after the muff, when the whole system including cat and downpipe was dropping ~4.
Last edited by JasonC SBB; 06-01-2015 at 02:06 PM.
#45
That was my concern in the muff thread too, and then brainesack berated me for it, and since I'm too lazy to test this sorta stuff I just kinda didn't care.
In theory the noise redux should be significant, no idea about turbulence because it's likely not as significant as the sweet sweet quietness
In theory the noise redux should be significant, no idea about turbulence because it's likely not as significant as the sweet sweet quietness
#51
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Well don't get me wrong, flow is still super important. If I didn't care about flow at all there would be a louvered resonator in there along with a chambered muffler. I see the 1x579 series as a very minor compromise in the flow vs sound debate. It was a minor compromise I was willing to make, and I'm glad to provide data once its up and running.
In fact, if someone is willing to loan us a 1x578 or 1x589 series muffler, or if I can convince Gesso to buy one for his project, we can splice it into my exhaust and do some legitimate "all things being equal" back-to-back testing with Cordus' sensor setup. That'll really give us solid data.
In fact, if someone is willing to loan us a 1x578 or 1x589 series muffler, or if I can convince Gesso to buy one for his project, we can splice it into my exhaust and do some legitimate "all things being equal" back-to-back testing with Cordus' sensor setup. That'll really give us solid data.
#52
In fact, if someone is willing to loan us a 1x578 or 1x589 series muffler, or if I can convince Gesso to buy one for his project, we can splice it into my exhaust and do some legitimate "all things being equal" back-to-back testing with Cordus' sensor setup. That'll really give us solid data.
--Ian
#53
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I like this plan. I'll add some mild bungs to my shopping list, and maybe an additional stainless one for the downpipe.
Out of curiosity, where would you recommend putting them/where exactly are the ones located in your FM?
Out of curiosity, where would you recommend putting them/where exactly are the ones located in your FM?
#54
Actually, now that I look at the photo, I'm not sure there *is* one in the midpipe after all. The downpipe ones are obvious in the photo, and the post-cat one is right under the exhaust hangar for the midpipe in the photo.
For pressure sensing between the cat and the muffler, I don't really think it matters all that much, the pressure should be pretty constant all the way along the pipe. If you're trying to measure turbine performance, I think it's better to have them right before and after the turbine itself.
--Ian
#55
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Pre-turbine is going to be a problem for me. There really is no convenient place to put on in my manifold, plus its coated, or I could drill and tap a hole in the EFRs turbine housing. I'm not sure I'm crazy about either TBH. Someplace in the downpipe is do-able as is before the first resonator. We'll figure something out.
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