M3 Cowl conversion for E9X

doublespaces

General of the Army
Oct 18, 2016
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2009 E93 335i
Intro

20180207_193624.jpg

This has been a fairly popular modification over the years for a number reasons, with the main being the easy access to the engine bay. The factory cowl overhangs the engine cover and its required to be removed before other work can be done in the engine bay. The M3 cowl eliminates that process and also gives the engine bay a more open look, particularly nice for those with aftermarket intake manifolds or valve covers.

Parts List:

64316958817 Filter Housing Lower Left
64316958818 Filter Housing Lower Right
64316958815 Filter Housing Upper Left
64316958816 Filter Housing Upper Right
64319159606 Filter -> Aftermarket: Mann CUK 22 008-4
51718045623 Sealing (You can re-use your stock hood seal if its in good condition)
07143428231 Plastic Screws x6 (Assuming you don't keep your stock bolts, you'll use 10 of these total)

Optional Cable Guide, buy from schmiedmann.com:
12527838732 Cover for cable guide
12527838733 Cable guide

Installation

Start by removing the stock cowl, and then take the left(driver) portion of the cowl which is the longer side, and slide it onto the rubber seal next to the firewall. Use the factory bolt to secure this down as well as the rubber clips that hook into the sides.
20180207_145926.jpg 20180207_150014.jpg

Go ahead and install the right piece of the cowl. In the center, this piece sits on top of the other piece.
20180207_150928.jpg

Next, break the three plastic tabs off the cowl to make room for the cable guide:
20180207_154037.jpg 20180207_154101.jpg

Go ahead and use three screws to fasten this cable guide to the cowl:
20180207_154350.jpg

Now take the fatter wiring loom and stick it up into the larger of the two cable guide channels. This wire may be tight so be careful with how you handle it. If it doesn't reach you may have to undo the harness package on the bottom of the intake manifold in order to get room. Mark the loom on each side of the guide where the lines become exposed, and carefully cut the plastic shield off the loom:
20180207_164529.jpg

Using black tape, re-tape over the exposed wires on the loom, make sure there are no holes so it is water tight:
20180207_171450.jpg 20180207_185618.jpg

Now take the smaller of the corrugated looms and stick it in the aft slot. It should be a perfect size and clip in. Right hand drive cars may have a larger loom and will need cut like the previous step. Next, take the newly taped loom and stick it in the next cable guide slot. Install the top of the cable guide and then hang the last wire on the exposed hooks.

Now install the new cabin filters and using the screws, install onto the cowl. If you have an alarm, the sensor should snap into the left side of one of the cabin filters.
20180207_192635.jpg

You're done!
 

JOEinSD

Private
Mar 31, 2017
40
16
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N54 335i
Thanks. Have had this on the to-do list, but hasn't been a priority. It keeps getting bumped down by maintenance and other mods. Lol.
 

doublespaces

General of the Army
Oct 18, 2016
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2009 E93 335i
Here are a couple thoughts about this change:

  • The RHD cars have different wiring looms. I was looking at someone who did this before and their looms were different not to mention they went across the engine bay the other direction in some cases.
  • The fat loom is too short. The length of cable from the DME box to the wiring junction box that attaches below the intake manifold is not long enough. I don't know if this is due to my custom intake manifold but I had to leave that junction box disconnected to give it the slack it needed.
  • There is an air quality sensor on the right(passenger) side and the wire does not reach its new location. I'll need to make or buy an extension cable.
  • The cowl is incredibly sharp. I sliced off a few pieces of skin just running my hand along the inside edges of this thing. I recommend wearing gloves or even filing some of it down.

Here you can see the wire for the air quality sensor is too short:
ocIR5Ya.png
 

LMB335is

Sergeant
Apr 12, 2017
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FOB FL
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13 335is
Just splice a few inches of similar gauge wire in, use heat shrink tubing to seal it up, and finish off with OE style tape. You'll never know the difference and it will look OE.
20180208_124603.jpg
 
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soawesomeman

Private
Nov 8, 2017
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Seattle
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2009 E93 335i
@doublespaces After the conversion, does the seal rubber contact the 335i hood? It appears the M3 hood has a brace corresponding to the shape of the M3 seal rubber; whereas the 335i hood brace is straight to meet the straight 335i seal rubber. What would the ramifications be of not making that seal spanning the engine compartment? (just planning ahead)

%5B1a5772a12d9f28101e15bfecf24fa86f%5D_Image+2018-03-25+at+2.05.59+PM.png


BTW Thanks for the awesome documentation—I purchased the parts to do the cowl and the strut conversions.
 

doublespaces

General of the Army
Oct 18, 2016
8,943
4,150
0
AZ
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2009 E93 335i
@doublespaces After the conversion, does the seal rubber contact the 335i hood? It appears the M3 hood has a brace corresponding to the shape of the M3 seal rubber; whereas the 335i hood brace is straight to meet the straight 335i seal rubber. What would the ramifications be of not making that seal spanning the engine compartment? (just planning ahead)

%5B1a5772a12d9f28101e15bfecf24fa86f%5D_Image+2018-03-25+at+2.05.59+PM.png


BTW Thanks for the awesome documentation—I purchased the parts to do the cowl and the strut conversions.

I haven't checked this, but if you look at the driver vent, it comes down on top of the air box piece which sits fore of the seal. But on the hood, that lip is going right through the vent, so I'm not so sure that crease in the hood corresponds to that seal.
 

Jeffman

Captain
Jan 7, 2017
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If you don’t have a good seal then you may be pulling air from the engine bay into the cabin with heater/Ac vent setting to fresh.
 
Last edited:
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Orion1two

Lurker
Dec 14, 2019
13
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BMW 335I E90 AT
Yep, may be a good idea to get an M3 hood if you're gonna swap cowl's and your looking for perfection. very clean!
 
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The Convert

Captain
Jun 4, 2017
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Did someone try it with m3 hood? Does m3 hood fit?
M3 hood does not fit. It’s longer and requires fenders, bumper, inner fender liners, and some other odds and ends. Best solution would be to find a carbon hood company that would make you a hood with M3 underside.