Karbonius Carbon Fibre Stock S54 Plenum

[repoman89]

Can anyone confirm if Z4 and post-2004 M3 rubber couplings work with the CSL airbox? I have never read that they DON'T, but would like to confirm as the rubber boots are quite expensive.

They don't work.

[///MBan]

They don't work.

That's a bummer - thanks for clarifying. So Z4Ms and post-2004 M3s will also need to buy the rubber couplings.

[terra]

That's a bummer - thanks for clarifying. So Z4Ms and post-2004 M3s will also need to buy the rubber couplings.

Post 10/2004 M3s specifically. And even then the cutoff is somewhere in the middle of the month. My 2005 M3 was built in early October 2004, and it had the old rubber couplings.

[JDMaflac]

Following this topic off of zpost but i'm excited to see the next iteration with the brace in place.

[///MBan]

Karbonius have added a 'pillar' to the plenum to reduce the flex and re-tested. Volume appears to be unaffected. Possibly there's a slight change in tone? Video below.

To plan a production run, Karbonius are asking for people to indicate if they intend to buy one. I'll start a list on zpost (https://www.zpost.com/forums/showpost.php?p=29291402&postcount=150). Don't forget that Z4 people and post-10/2004 M3s will need to buy the old rubber couplings and matching clips for the plenum side (parts 3 and 4 here https://www.realoem.com/bmw/enUS/showparts?id=BL96-EUR-10-2003-E46-BMW-M3_CSL&diagId=11_3517). Or, you can buy the Turner silicone coupling kit, which is quite a bit cheaper than buying new OE parts.

Karbonius plenum with extra reinforcing:

https://youtube.com/shorts/-6nf6_zrNxY?feature=share

Karbonius plenum without reinforcing:

https://youtube.com/shorts/NtCRPz1705A?feature=share

[heinzboehmer]

That video with the reinforcement sounds much more like a CSL airbox. Good stuff.

[Toby22]

Is it possible to do comparison video using same camera/distance etc.

stock intake - karb plenum - csl intake

[///MBan]

Is it possible to do comparison video using same camera/distance etc.

stock intake - karb plenum - csl intake

They did provide videos for each of those. See below. Or do mean something else?

Stock

https://youtube.com/shorts/LV8jRFmXMyg?feature=share

CSL-style:

https://youtube.com/shorts/D8S_IVLXTEc?feature=share

[cliptheapex]

Can I also be added to the list?

[///MBan]

Can I also be added to the list?

Absolutely - done.

[LateBraking]

That video with the reinforcement sounds much more like a CSL airbox. Good stuff.

I agree.

Wonder why just the one. IIRC the OEM/Karbonius CSL airbox came with two pillar reinforcements inside? I feel like I can still see it flexing a bit at the ends but it looks much better than before, and I agree that the tone sounds closer to the CSL airbox now. Maybe the flexing changed the tone a little? I can't recall my old Karbonius CSL airbox doing this.

I think I'd be on board with the two pillars like found on the CSL airbox. With one pillar I'm on the fence a bit, and with no pillars I'm probably not in.

[///MBan]

I agree.

Wonder why just the one. IIRC the OEM/Karbonius CSL airbox came with two pillar reinforcements inside? I feel like I can still see it flexing a bit at the ends but it looks much better than before, and I agree that the tone sounds closer to the CSL airbox now. Maybe the flexing changed the tone a little? I can't recall my old Karbonius CSL airbox doing this.

I think I'd be on board with the two pillars like found on the CSL airbox. With one pillar I'm on the fence a bit, and with no pillars I'm probably not in.

I think there are multiple pillars. The first email said 'pillar' (singular), but the message I received with the video said, "... we have test with pillars and we get to reduce flex without loose sound... [sic]".

I will double-check though.

[TeddybearCup]

Please add me to this list!

[///MBan]

Please add me to this list!

Thanks - will do!

[///MBan]

I still don't have a firm production / delivery date but I can confirm the price will be 1,280 Euro and that people will purchase directly through Karbonius's website.

I agree.

Wonder why just the one. IIRC the OEM/Karbonius CSL airbox came with two pillar reinforcements inside? I feel like I can still see it flexing a bit at the ends but it looks much better than before, and I agree that the tone sounds closer to the CSL airbox now. Maybe the flexing changed the tone a little? I can't recall my old Karbonius CSL airbox doing this.

I think I'd be on board with the two pillars like found on the CSL airbox. With one pillar I'm on the fence a bit, and with no pillars I'm probably not in.

Karbonius have confirmed two reinforcement pillars have been used (just like their CSL airbox).