Black & Tan 332iT

[heinzboehmer]

I think these are the possibilities:

1. Karb snorkel is not the same dimensionally as OE.
2. My intake isn't fully seated.
3. My car's bumper fitment is off.
4. My car's stamped aluminum brake duct bracket is far too bent out of shape (I know it is at least somewhat messed up).
5. Scanned car has some tweaked dimensions thanks to the fender bender.
6. Some unknown differences between early and late model years.

Okay so it turns out that none of these were correct. Actual culprit was the wishbone bracket under the airbox. Guess it got bent at some point:



Duct fits great with the bracket bent back to where it should be!

[Bry5on]

Might not actually be the worst idea to have a gap and flexible section, to accommodate the engine twisting under load.

Excuse to print something in TPU :P

By design there’s a 25mm gap and a flexible ‘accordion’ TPU boot. The boot slips over the duct, then the CSL snorkel ‘clips’ into the boot like factory and pulls the boot up slightly. The boot has 20mm of engagement so it can act like a slip joint and also can deform axially/radially. It’s the yellow modeled part in the section view above

In fact it would be better if you could attach something to the snorkel shaped like a funnel that goes over the intake pipe to decrease the chance of air turbulence and ensure the air gets rammed in regardless of engine tilt.

There is also a lead-in to the TPU boot to transition the ID smoothly instead of into an abrupt lip. I think this makes 0 difference practically but makes my OCD much happier. Also can be seen in the section view above.

[heinzboehmer]

Might not actually be the worst idea to have a gap and flexible section, to accommodate the engine twisting under load.

Excuse to print something in TPU :P

Bryson already designed that in

Issue with my car is that the duct alignment is too far off for the TPU coupler to accommodate (hence why I left it off for the pictures).

[YoitsTmac]

In fact it would be better if you could attach something to the snorkel shaped like a funnel that goes over the intake pipe to decrease the chance of air turbulence and ensure the air gets rammed in regardless of engine tilt.

[Obioban]

Might not actually be the worst idea to have a gap and flexible section, to accommodate the engine twisting under load.

Excuse to print something in TPU :P

[heinzboehmer]

Here are some pictures of the first test fit on my car:




That's the same duct (as in literally the same part) that's in Bryson's pictures. There's clearly something off about my car, the scanned car or both. I think these are the possibilities:

1. Karb snorkel is not the same dimensionally as OE.
2. My intake isn't fully seated.
3. My car's bumper fitment is off.
4. My car's stamped aluminum brake duct bracket is far too bent out of shape (I know it is at least somewhat messed up).
5. Scanned car has some tweaked dimensions thanks to the fender bender.
6. Some unknown differences between early and late model years.

Took my bumper off yesterday and found some failed plastic welds. They weren't in a spot that would have affected the duct, but I'm taking this opportunity to fix the fitment, as it's never been perfect.

I've messed with the fitment of the bumper a bit, but haven't fully mounted it back on. Super quick test fit before work this morning yielded much better fitment of the duct. I'll continue messing with it later.

But honestly, (1) above seems like the most likely culprit. Will keep testing.

[Bry5on]

Ok, standard M3 brake duct fits great on the car with a factory flap (but has a prior fender bender) and does not fit at all on heinzboehmer's car with the Karbonius snorkel. Time to print another and test fit on a second M3 after adding a couple little tweaks (more core support clearance, air transition into accordion boot).

[heinzboehmer]

Oh amazing! There were a couple of people working on this who then seemed to give up - I was going to get started on designing my own but won't if this is on the way!!! Very exciting!

Yeeep, same. It was on my todo list, but now I get to copy Bryson's homework! Easiest project ever

I'll report back here when it's done printing and I've test fitted it.

[karter16]

And by popular demand, iteration 1 of the stock M3 bumper to CSL intake duct is complete and off to heinzboehmer for a test fit:

Oh amazing! There were a couple of people working on this who then seemed to give up - I was going to get started on designing my own but won't if this is on the way!!! Very exciting!

[Bry5on]

The consistent feedback after driving here makes it sound like the braces stop the inherent deflection going through the chassis, essentially like solidifying a bushing. And when you start eliminating each point that 'gives' with it's own respective spring rate then you inevitably start to work the tire and damper themselves more.
(Hmm maybe I just reverse-engineered the secret of the MCL39... 😆)

This certainly does seem to validate precisely the way RACP's fail though!

Yep! Control is the name of the game here. Hard to control the chassis when it's acting as a relatively soft undamped spring.

I trimmed the isofix cover to clean up the install:


And by popular demand, iteration 1 of the stock M3 bumper to CSL intake duct is complete and off to heinzboehmer for a test fit:

[jvit27]

The consistent feedback after driving here makes it sound like the braces stop the inherent deflection going through the chassis, essentially like solidifying a bushing. And when you start eliminating each point that 'gives' with it's own respective spring rate then you inevitably start to work the tire and damper themselves more.
(Hmm maybe I just reverse-engineered the secret of the MCL39... 😆)

This certainly does seem to validate precisely the way RACP's fail though!

[Bry5on]

Randomly stumbled upon a picture of the underside of an F97 X3M and thought of your latest project



Different purposes served by each, but the approach (at least in terms of fastener location on the brace) is similar.

That looks a whole lot like the e46 non-m cabrio

[heinzboehmer]

Randomly stumbled upon a picture of the underside of an F97 X3M and thought of your latest project



Different purposes served by each, but the approach (at least in terms of fastener location on the brace) is similar.

[Bry5on]

Pleased to see the hat still makes a sneaky appearance in this latest post 😋

Really like that approach of tying the v-brace directly to the subframe - will be really interested to hear how it goes.

For some reason I'm struggling a little bit to visualize it - the arms of the bracket that stick down bolt through two new holes in the v-brace right? What I can't quite work out is where the main body of the bracket is bolting to as I didn't think there was as much vertical space there before you ran into the diff (I mean obviously I'm wrong, as you have a 3D scan of it haha). Is it two new holes in the front lower section of the subframe?

Here?

Hahaha that’s hilarious that you spotted the hat. Yes you’ve got the location correct, the plan is to pop two rivet nuts into the subframe there for ease of installation. The drain hole is left clear to prevent any future rusting from the inside out.

Honestly I would prefer a single joggled sheet that bolts through the vbrace fastener, but that would space the vbrace down even further than it already is (damn subframe plates). If this ends up being fiddly to install but the results are conclusively good, i might just weld a simple sheet to the factory U-brace above the v-brace.

I picked up a spare v-brace yesterday from a friend who was sitting on a lot of them, so the worse of the two will be getting holes drilled into it to fit this.

[karter16]

Pleased to see the hat still makes a sneaky appearance in this latest post 😋

Really like that approach of tying the v-brace directly to the subframe - will be really interested to hear how it goes.

For some reason I'm struggling a little bit to visualize it - the arms of the bracket that stick down bolt through two new holes in the v-brace right? What I can't quite work out is where the main body of the bracket is bolting to as I didn't think there was as much vertical space there before you ran into the diff (I mean obviously I'm wrong, as you have a 3D scan of it haha). Is it two new holes in the front lower section of the subframe?

Here?