This should help make up for last week's redundant airbox post. With the airbox lid removed we can see some impressive details which allow this monster to breathe. The bottom arrow points to one of the airbox's three intakes. This one supplies air which is gathered through the twin-kidney grille and routed above the radiator to this hole.
The top arrow addresses your questions about water draining into the airbox through the hood duct. The small slit in the bottom of the airbox offers drainage for small amounts of water. However, should some genius decide to run a garden hose in that duct, the overflow would simply drain out the intake hole in the front bumper (driver's side) which is the lowest point in the airbox. Click through for more details.
This view offers perspective from above and behind the filter with the camera facing forward and down into the airbox. The arrow in the foreground points to the same water drainage slit we saw pointed out by the top arrow in the above image.
The upper arrow in this image points to the daylight visible through the duct in the front bumper (see below).
BMW has done an elegant job of offering a huge amount of cool airflow to the engine without risking drowning the air filter and hydro-locking the engine. There's ample opportunity for air to get into the airbox and ample opportunity for water to escape.
And just to make it harder for you to mess with it, those crazy Germans attached the airbox lid with eight of these Torx fasteners
Josh Jacquot, Senior road test editor @ 8,671 miles
briancam says:
12:26 PM, 09/14/09
I see you found my pet moth.
crowb says:
12:45 PM, 09/14/09
Cool post, Josh! Any technical details are always welcome. I still think you guys should consider engine/transmission walk arounds similar to the suspension walk arounds. It might be difficult (or ill advised) to tear everything down yourself just for the sake of pictures, but surely the manufacturers have stock photos and diagrams you can work with.
The M3 would be a great subject for a walk around. I'd like to know all of the engineering and manufacturing tricks (materials, design, etc.) they used to squeeze so much naturally aspirated power out of 4 liters.
kevinlch says:
03:02 PM, 09/14/09
Good info, always good to know more details like these.
billt9 says:
03:06 PM, 09/14/09
is that an aluminum screw???
jaguar36 says:
04:45 AM, 09/15/09
I love Torx screws, they're so much easier to use, and so much less likely to strip than either a phillips or a hex.
mlevere1992 says:
06:28 AM, 09/15/09
I just wish that this was the box that they put on the 335. That thing is too small.
opfreakx says:
07:40 AM, 09/15/09
I agree with Jag, torx is awesome.
greenpony says:
06:20 PM, 09/15/09
Eight??? Sweet Jesus, are they afraid that a traditional clasp system won't offer enough clamping force to keep the airbox from imploding at max power?
911cs2 says:
06:35 PM, 10/ 1/09
Re the 8 screws and the multiple flow solutions: it's details like these that you CAN'T see that keep me buying my German sports cars. Love the work that ///M Div do: around 80% of the E9x M3 is different from the standard 3ers so for those that just want to chip a 335i to beat an M-car .... think about it.