S4-up airbox throat diameter?
#1
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Where it slides over the MAF adapter (92811013200).
Anyone have that off-hand, please?
Anyone have that off-hand, please?
#2
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Ken- You mean this diameter? 96.40 mm?
Camera, airbox and calipers are out if this is the wrong dimension.
Camera, airbox and calipers are out if this is the wrong dimension.
![](https://webfiles.uci.edu/redwards/public/S4%2B%20airbox%20MAF%20ring%20ID%205-30-12.jpg)
#3
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Rob - that's the one. Thanks!
(Shoulda just PM'ed you, cuz I figured...
)
Interesting... ~96.5 mm ≈ 3.8"
Carry on, nothing to see here.
(Shoulda just PM'ed you, cuz I figured...
![Big Grin](https://rennlist.com/forums/images/smilies/biggrin.gif)
Interesting... ~96.5 mm ≈ 3.8"
Carry on, nothing to see here.
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#4
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I doubt that. Recall that an old man named Z in Chicago a long time ago devised a ply-material to essentially smooth the transition from the filter-box surface to the throat of the MAF connector....
A very, very long time ago.
A very, very long time ago.
#5
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FWIW, that inlet ring is of course pliable, and its inner lip is not parallel when installed, so that it's about 94 mm at the 'inlet' and 97-ish mm at the outlet. Perhaps more importantly from a flow standpoint, underneath the rubber ring, the hole in the lower airbox is only 85.75 mm in diameter:
'Inlet'
![](https://webfiles.uci.edu/redwards/public/S4%2B%20airbox%20MAF%20seal%20inlet%20OD%2094mm%205-30-12.jpg)
'Outlet'
![](https://webfiles.uci.edu/redwards/public/S4%2B%20airbox%20MAF%20seal%20outlet%20OD%2097mm%205-30-12.jpg)
Minimum ID of plastic airbox opening:
'Inlet'
![](https://webfiles.uci.edu/redwards/public/S4%2B%20airbox%20MAF%20seal%20inlet%20OD%2094mm%205-30-12.jpg)
'Outlet'
![](https://webfiles.uci.edu/redwards/public/S4%2B%20airbox%20MAF%20seal%20outlet%20OD%2097mm%205-30-12.jpg)
Minimum ID of plastic airbox opening:
![](https://webfiles.uci.edu/redwards/public/S4%2B%20airbox%20inner%20diameter%2085-73mm%205-30-12.jpg)
#6
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Awesome Rob. I'm actually interested in the doughnut, not the airbox, so the additional pics are great. (A+)
I'm trying to determine if a 4" OD pipe can be pressed on to the MAF using that factory part.
Actually, could you do a side shot/measurement of the rubber seal/adapter, please?
I'm trying to determine if a 4" OD pipe can be pressed on to the MAF using that factory part.
Actually, could you do a side shot/measurement of the rubber seal/adapter, please?
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#8
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Like this?
![](https://webfiles.uci.edu/redwards/public/S4%2B%20airbox%20MAF%20seal%2021-39mm%20thick%205-30-12.jpg)
(And while we're measuring stuff: )
![](https://webfiles.uci.edu/redwards/public/S4%2B%20airbox%20MAF%20seal%20overall%20OD%20120%20mm%205-30-12.jpg)
![](https://webfiles.uci.edu/redwards/public/S4%2B%20airbox%20MAF%20seal%20inner%20step%20OD%20104-87%20mm%205-30-12.jpg)
![](https://webfiles.uci.edu/redwards/public/S4%2B%20airbox%20MAF%20seal%2021-39mm%20thick%205-30-12.jpg)
(And while we're measuring stuff: )
![](https://webfiles.uci.edu/redwards/public/S4%2B%20airbox%20MAF%20seal%20overall%20OD%20120%20mm%205-30-12.jpg)
![](https://webfiles.uci.edu/redwards/public/S4%2B%20airbox%20MAF%20seal%20inner%20step%20OD%20104-87%20mm%205-30-12.jpg)
![](https://webfiles.uci.edu/redwards/public/S4%2B%20airbox%20greatest%20airbox%20ID%20106-40%20mm%205-30-12.jpg)
#9
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That last photo shows me that my 4" idea is a no good. ![nono](https://rennlist.com/forums/graemlins/nono.gif)
In the mean time, though, I think I have found a 3.5" option (Vibrant aluminum bellmouth).
FWIW, the '85-'86 32V ('84-'86 ROW 16V) MAF to airbox hose, 928 110 243 02, is a ~3.75" to ~3.5" adapter.
![nono](https://rennlist.com/forums/graemlins/nono.gif)
In the mean time, though, I think I have found a 3.5" option (Vibrant aluminum bellmouth).
FWIW, the '85-'86 32V ('84-'86 ROW 16V) MAF to airbox hose, 928 110 243 02, is a ~3.75" to ~3.5" adapter.
![Wink](https://rennlist.com/forums/images/smilies/wink.gif)
Last edited by PorKen; 05-31-2012 at 12:45 PM.
#10
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I find your lack of faith, disturbing...
If you dial in enough cam retard, those little valves can breathe more deeply.
Enough to need more than the stock airbox can supply, Mr. Man.![Stick Out Tongue](https://rennlist.com/forums/images/smilies/tongue.gif)
(There is also less vacuum to pull through the stock filter.)
![Embarrassment](https://rennlist.com/forums/images/smilies/redface.gif)
![](http://members.rennlist.org/porken/86_5_K&N_lid.jpg)
![](http://members.rennlist.org/porken/smiley_vader.gif)
If you dial in enough cam retard, those little valves can breathe more deeply.
Enough to need more than the stock airbox can supply, Mr. Man.
![Stick Out Tongue](https://rennlist.com/forums/images/smilies/tongue.gif)
(There is also less vacuum to pull through the stock filter.)
![Embarrassment](https://rennlist.com/forums/images/smilies/redface.gif)
![](http://members.rennlist.org/porken/86_5_K&N_lid.jpg)
![](http://www.bpi-us.com/images/stack_diagram.jpg)
Last edited by PorKen; 05-31-2012 at 02:38 AM.
#11
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Hi, I saw this thread & I'm considering modifying or trading my s4 airbox with a universal conical filter and silicone ducting hose (a sort of home-made CAI).
I was wondering if the results you had is worth the effort & expense?
Thank's
I was wondering if the results you had is worth the effort & expense?
Thank's
#13
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