Alternative "cowl filter" mod - No water Entry

[MMcGyver]

My first thread on here will be to share an alternative to what I consider a very foolish option of deleting the Cowl & installing a BMS (Or similar) filter setup.
The goal of course for most of us is to introduce some engine noise into the cabin. This is frankly the #1 reason people do the Cowl delete & Cowl filters.

Your 1er is not a race car (unless it is) and it is my opinion because of this should NOT be deleting the cowl, it serves a very important function (directing water, snow melt, etc off the windshield) and is incredibly well designed and good at it. Without it this water WILL enter areas it shouldn't and eventually cause you problems. Most importantly the DME is located RIGHT THERE and with cowl removed you'll be exposing it to a lot of water.

Let's cover quickly a couple alternate reasons people cite for doing this mod:

a) weight reduction - well.... it does SEEM heavy but is actually only 7lbs despite what BMS advertises! So let's not get out of hand here, almost nothing reduced and certainly NOT worth toasting Electronics or seized injectors/plugs at the back of motor, etc

b) Underhood heat dissipation - You won't hear me argue this, it's true, but I do have a couple alternatives to help with that without losing the water channeling.


Now, onto an alternative, cleaner, more "OEM" option (Oh, and it's FREE). Not sure if someone has posted about this before, if so sorry for a repeat. No filter replacement is required (unless your OE filter is due for replacement anyways).

Essentially all you need to do is remove the cowl and cut a hole in it. You'll want to be sure to mark the cowl with the filter cover in place, and ensure you don't 'over-cut' so the hole would be visible with the filter cover on. this keeps an OEM look.

Next ensure this hole is on the 'raised' part of the cowl, leave about 1" all around (pictures) so if water does enter it will not go down the hole.

Then clean the hole up, sand it nice if you like, but ensure there's not plastic particles on anything prior to reassembly on vehicle.

Reassemble and enjoy!


Extras:

-->> #1
I removed the weather stripping that seals the hood to the front of the cowl piece, this is meant to isolate the cowl area from the engine bay. Removing it is the easiest thing you can do to increase engine noise in cabin, and also remove heat from engine bay (engine venting).
There is no real downside to this worth noting.

-->> #2
You can (I might later) still use BMS filters on the cowls, and remove the top filter/cover assembly with this setup. This will help with engine heat removal, but you will lose a small part of the water protection which is created by the 'v' shape of the filter cover (see photos to see how much it blocks and re-directs water away from getting into the cowl area at all)

-->> #2b
I have an idea to use BMS cowl filters but cut/modify the stock filter cover, remove stock filter, this way you'll get more venting (and a tiny bit more noise) but still have the center 'v' shaped piece in place to direct water.
Downside is this ruins the piece so you can't go back to stock, and will not look OEM underhood.


Please review photos and ask any questions. I hope you find this a nice alternative method to get some heat dissipation & Engine noise in cabin without risking damage to DME and other components. Also save money on those Cowl filters, as this DIY is FREE

It's MUCH louder than stock!

REVIEW/COMPARISIONS:
I've run and tested the following setups during this production

1. no cowl, no filters
2. No cowl, BMS filters
3. only Lower Cowl on, BMS filters
4. lower cowl on, no filters
5. Hole cut in lower cowl, BMS filters
6. Hole cut in Lower cowl, stock filter

I can after a lot of testing say that the method shown (stock filter & hole in lower cowl) is almost indistinuighable from the 'loudest' no cowl, no filters, and anything in between.
Thus if the goal is noise + some engine cooling without risking damage to components, this is, IMO by FAR better than any cowl delete or BMS/Cowl filter modification.

[Papa Popov]

Damn good idea! Might have to give this a go.

Curious as to how much (if any) water this lets though. Obviously the sensitive bits are still protected, but I'm not a fan of letting water into my engine bay.

[jshbrwr]

Thinking about this and have read a few posts regarding the BMS filters and the pros/cons...

Right now I'm considering getting the BMS filters simply for their reusability, and then potentially cutting the hole as you've done, and reinstalling the tray and the cover as stock...maybe removing the weather strip and seeing how that adds a little more sound.

I've done the charcoal delete, KN filter upgrade, and am *this close* to getting a silicone pipe to replace the section between the MAF and the TB.

Thanks for posting this guide, with pictures!

[turbo v6]

This is still my favorite:
https://www.1addicts.com/forums/show...hlight=m3+cowl