Very quiet turbo exhaust - LFN sensitivity
07-14-2017, 04:58 PM
#62
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Location: Columbus, IN
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Ok, thanks, very good to know!
I know everyone keeps saying that the magnaflow should be more than sufficient...The reason I seem to be going to extraordinary lengths is because, for whatever reason, my ears seem to be a lot more sensitive to low frequency sound than most people's. Since it would be supremely anti-climactic, to say the least, to build a turbo car and then not be able to drive it without going deaf, I just want to make as sure as possible to make the car as quiet as possible. It appears that two resonators or straight through mufflers are about as good as it's going to get, so now it's just a matter of determining which resonators will work the best.
I guess, in the end, they'll all probably be similar, and worst case I'll just mount a flapper like Jason and be done with it.
I know everyone keeps saying that the magnaflow should be more than sufficient...The reason I seem to be going to extraordinary lengths is because, for whatever reason, my ears seem to be a lot more sensitive to low frequency sound than most people's. Since it would be supremely anti-climactic, to say the least, to build a turbo car and then not be able to drive it without going deaf, I just want to make as sure as possible to make the car as quiet as possible. It appears that two resonators or straight through mufflers are about as good as it's going to get, so now it's just a matter of determining which resonators will work the best.
I guess, in the end, they'll all probably be similar, and worst case I'll just mount a flapper like Jason and be done with it.
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07-14-2017, 07:28 PM
#66
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Ian! 
I got poked so I'll chime in and see if I can help. I will preface my comments by saying that sound is ridiculously subjective, and I can only give my impressions. You really need to go out and get a ride in one of these things under full power to judge for yourself. So the two quietest 300+HP turbo exhaust I have direct experience with are Codrus' and my own. You've seen mine, and I believe Codrus is running an off the shelf 3" FM turbo exhaust.
Now keep in mind, neither of our exhausts are "silent" but they are definitely "quieter" than pretty much any other free flowing 3" turbo exhaust I've ever heard on a Miata. My exhaust has zero high frequency noise, but I need to warn you, there is a lot of lower tones still present.
As for cat, I have toyed with the idea of adding a cat just to see how much of a difference it would make. Probably one of the 200 or 300cpi metal core ones that seem to be avalible in the aftermarket. Put it on vbands and of course remove it for trackday shenanigans. Of course, its not like a cat would be any kind of approved or make my exhaust any more legal, but I feel like its something I might want to try at some point, so we'll see.
As for the flapper valve, if someone made one that I could push the easy button and order I'd probably have done it. When we built my exhaust, nothing existed other than eBay garbage that would just rattle itself to death and fall apart, so I didn't bother.
As for resonator, I picked the Vibrant with the largest internal volume that I could actually fit in the car. More internal volume = more reduction. You can also move the resonator around in the exhaust to see if it hits a "sweet spot" to help with certain frequencies, but that kind of "tuning" tends to get expensive if you are not DIY-ing an exhaust. Also, that cheese grater resonator is LOL, the Vibrant looks NOTHING like that internally. They are truly a nice part.
Please note that my muffler is not the "standard" MT.net muffler. Search the PN here on MT and you'll see a thread detailing the difference.
I got poked so I'll chime in and see if I can help. I will preface my comments by saying that sound is ridiculously subjective, and I can only give my impressions. You really need to go out and get a ride in one of these things under full power to judge for yourself. So the two quietest 300+HP turbo exhaust I have direct experience with are Codrus' and my own. You've seen mine, and I believe Codrus is running an off the shelf 3" FM turbo exhaust.
Now keep in mind, neither of our exhausts are "silent" but they are definitely "quieter" than pretty much any other free flowing 3" turbo exhaust I've ever heard on a Miata. My exhaust has zero high frequency noise, but I need to warn you, there is a lot of lower tones still present.
As for cat, I have toyed with the idea of adding a cat just to see how much of a difference it would make. Probably one of the 200 or 300cpi metal core ones that seem to be avalible in the aftermarket. Put it on vbands and of course remove it for trackday shenanigans. Of course, its not like a cat would be any kind of approved or make my exhaust any more legal, but I feel like its something I might want to try at some point, so we'll see.
As for the flapper valve, if someone made one that I could push the easy button and order I'd probably have done it. When we built my exhaust, nothing existed other than eBay garbage that would just rattle itself to death and fall apart, so I didn't bother.
As for resonator, I picked the Vibrant with the largest internal volume that I could actually fit in the car. More internal volume = more reduction. You can also move the resonator around in the exhaust to see if it hits a "sweet spot" to help with certain frequencies, but that kind of "tuning" tends to get expensive if you are not DIY-ing an exhaust. Also, that cheese grater resonator is LOL, the Vibrant looks NOTHING like that internally. They are truly a nice part.
Please note that my muffler is not the "standard" MT.net muffler. Search the PN here on MT and you'll see a thread detailing the difference.
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07-14-2017, 10:03 PM
#67
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Thanks EO2K, I appreciate the input.
So this is what concerns me. I agree, I just need to find a turbo miata and hear it for myself. I know there is at least one in the area, it's been sighted at the local autocross event. I'll start asking around, someone I know is bound to know who it is.
Just a thought; Jason mentioned he didn't need the flapper valve with his 2.5" exhaust. I don't have any intention of going for more than 220-230 whp in the foreseeable future. Certainly not while it's a dd. Do I really need 3" exhaust at that power? Would going with a 2.5" exhaust make the lower frequency sound significantly more manageable? (Note, I'm not assuming here that Lars would make me a 2.5", I'm just hypothesizing).
My exhaust has zero high frequency noise, but I need to warn you, there is a lot of lower tones still present.
Just a thought; Jason mentioned he didn't need the flapper valve with his 2.5" exhaust. I don't have any intention of going for more than 220-230 whp in the foreseeable future. Certainly not while it's a dd. Do I really need 3" exhaust at that power? Would going with a 2.5" exhaust make the lower frequency sound significantly more manageable? (Note, I'm not assuming here that Lars would make me a 2.5", I'm just hypothesizing).
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07-18-2017, 08:18 AM
#74
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Quick, find a safe space! If that fails, we can schedule a cry-in so you can express your feelings in imaginary isolation from the real world, and receive gratuitous validation of your laziness.
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07-18-2017, 01:42 PM
#75
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Officially ordered MKTurbo kit! Lars is going to try to fit 2 ultra quiet vibrant resonators...we shall see how it goes. I'll update this thread with audio clips once it's all installed and running.
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