My 3" custom spring loaded flapper valve
#1
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My 3" custom spring loaded flapper valve
JasonC SBB had this thread about removing his spring loaded flapper from a Dynomax VT muffler. It was a great idea and I was going to do the same because my Outback Wagon has a slightly annoying drone. But the ~$90 price tag for the muffler is borderline silly for a slight drone, even though I could probably use the discarded muffler section as a resonator for some future project... So anyway I made one with $15 worth of raw material from McMaster and about $300 worth of my time.
I don't know if it works yet. It probably won't. If it rattles I will make a nice soft stop for the flapper. I will update once I hold it up to my exhaust pipe and make the wife rev it up.
More pictures here:
Flap flap flap
I don't know if it works yet. It probably won't. If it rattles I will make a nice soft stop for the flapper. I will update once I hold it up to my exhaust pipe and make the wife rev it up.
More pictures here:
Flap flap flap
#2
Nice!
Can you mass produce and sell it? Oh wait better check what they've patented. (mm, Patent pending it seems)
Note:
1) that the lever arm must be such that the torque required to hold it open is greatly reduced than that to begin swinging it open. (It almost over-centers). Torque to hold it open is actually almost zero.
2) the Dynomax design has a notch in the small side of the flap for the gas to flow when closed. The notches should not be on the large side so that gas pressure will torque it open
3) the dynomax flapper has some kind of steel wool attached on the edge of the flapper that hits the pipe to prevent clattering noises.
Can you mass produce and sell it? Oh wait better check what they've patented. (mm, Patent pending it seems)
Note:
1) that the lever arm must be such that the torque required to hold it open is greatly reduced than that to begin swinging it open. (It almost over-centers). Torque to hold it open is actually almost zero.
2) the Dynomax design has a notch in the small side of the flap for the gas to flow when closed. The notches should not be on the large side so that gas pressure will torque it open
3) the dynomax flapper has some kind of steel wool attached on the edge of the flapper that hits the pipe to prevent clattering noises.
#4
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Note:
1) that the lever arm must be such that the torque required to hold it open is greatly reduced than that to begin swinging it open. (It almost over-centers). Torque to hold it open is actually almost zero.
1) that the lever arm must be such that the torque required to hold it open is greatly reduced than that to begin swinging it open. (It almost over-centers). Torque to hold it open is actually almost zero.
2) the Dynomax design has a notch in the small side of the flap for the gas to flow when closed. The notches should not be on the large side so that gas pressure will torque it open
3) the dynomax flapper has some kind of steel wool attached on the edge of the flapper that hits the pipe to prevent clattering noises.
AND thank you for the idea, again.
Same here. I'll work on that.
#8
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I duct taped it to my exhaust pipe and it was obvious I needed a tighter spring. But at idle, with it slapping around, it was a lot quieter in and out of the car.
It's been sitting on my garage shelf since.
It's been sitting on my garage shelf since.
#9
urrrrrrrrrrrrrrrrrggggggghhhhhhhhhhhh
I need one real bad.
found one on fleabay. not sure cause it doesn't really state spring pressure or anything. But it's $40, which is good IMO.
Basically I'm trying to figure out a way to tone down the low end pulses on the WRX.
It has a KillerB "holy" header, which flows amazing.
It has a blouch 10cm hotside which flows amazing.
It has a 3", very free flowing exhaust setup which flows amazing.
At WOT and at high rpm, it sounds amazing.
.....but,
At low rpm, I'm talking 1500-2100, I have some serious exhaust pulses/noise that is annoying, that goes away just past 2100rpm.
I need one real bad.
found one on fleabay. not sure cause it doesn't really state spring pressure or anything. But it's $40, which is good IMO.
Basically I'm trying to figure out a way to tone down the low end pulses on the WRX.
It has a KillerB "holy" header, which flows amazing.
It has a blouch 10cm hotside which flows amazing.
It has a 3", very free flowing exhaust setup which flows amazing.
At WOT and at high rpm, it sounds amazing.
.....but,
At low rpm, I'm talking 1500-2100, I have some serious exhaust pulses/noise that is annoying, that goes away just past 2100rpm.
#10
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Ahh I See. Is the exhaust tip pointing downwards at all? Does the tip extend out past the edge of the bumper?
Fixing those two issues made me not have to install my flapper mcflapflap.
EDIT: I'm interested in seeing your dyno changes if you weld this into your exhaust though.
Fixing those two issues made me not have to install my flapper mcflapflap.
EDIT: I'm interested in seeing your dyno changes if you weld this into your exhaust though.
#11
It's a Cobb quad-tip slant tip exhaust. The tips are only a tiny bit slanted, and no it's not pointing down. Yes they go just a tiny bit past the bumper. It's a really quality piece that actually sounds really quiet on any other setup but mine (my setup right now is, IMHO, perfectly maxed out, 10/10 flowing about as good as it can)
I too am hoping it doesn't hinder the flow too much
What I'm even more interested in is a 2-bolt 3" electronic cutout so I can place it directly into the stream and be able to open it on commant rather than waiting for pressure to do it, but it doesn't seem like that's a thing
I too am hoping it doesn't hinder the flow too much
What I'm even more interested in is a 2-bolt 3" electronic cutout so I can place it directly into the stream and be able to open it on commant rather than waiting for pressure to do it, but it doesn't seem like that's a thing
#12
<p>Somewhat interested in this.. Would be nice to have my car quieter around town, but still the option to be fully open, without having to put in or take out a silencer. <br /><br />Curious, though it will not apply to me, what impact these will have on your turbo spool.<br /><br />In4 guinea pig.</p>
#18
Let us know how it goes! Here is the apexi one if you're curious, almost identical.
Exhaust Control Valve, Flange-Type (80mm.)
Exhaust Control Valve, Flange-Type (80mm.)