Karbonius CF reproduction of standard S54 plenum **PROTOTYPE VIDEO**

[maupineda]

I am not convinced by that solution, if it fits the opening I see the point, but it is now just something else that could break / go wrong, plus you are effectively making the main intake opening smaller.

The box should of had a lip molded, not sure there is a real solution unless they redesign it, but due to low demand (I hope I am wrong) it very likely won’t happen.

The good news is that is not the end of the world as it can be made to work perfect as is with minimal cost and effort.

I may order my “fix” kit just in case, but almost certain I wont use it.

[Barryb97]

Originally Posted by Barryb97

Received my kit and attempted to install it tonight. The ring is too large to fit inside the opening. I tried sanding the intake a bit. No go. Then I tried heating the intake and putting the ring in the freezer. Still no go. I don't want to be too rough with anything and break it. Any other experiences with the new "Fix"?

Very frustrated!

Finally after a lot of heat and pushing I was able to get it to snap in. Hopefully the glue holds and all will be great!

I also sent an email to Karbonius and the responded immediately offered to send me another kit. Great customer service!

[86Zed]

Originally Posted by maupineda

The box should of had a lip molded, not sure there is a real solution unless they redesign it, but due to low demand (I hope I am wrong) it very likely won’t happen.

It seems you will be unconvinced by any potential fix short of a refund and revised mold design from Karbonius? Chances of that are slim to none from an aftermarket company supporting a low volume old platform. It is what it is and I agree it was an unfortunate oversight.

This Nylon lip, adhesive, and perhaps anti-slip tape for a belt and suspenders approach seems like an appropriate fix.

[Jdmaflac]

I finally installed my Karb OEM airbox 2 weeks ago after running my Eventuri intake for a few months to get acquainted with the sound (other mods: euro headers, X Rasp section 1, stock section 3). I wanted to make sure my installation went correctly since I had to use worm clamps on the manifold side and didn't want to snug up too much on the carbon fiber piece so with the help of a friend we did a smoke test. Found out in the shared video that both bottom corners of the airbox itself leaks, granted the engine doesn't throw any lean codes but I feel like there's a slight hesitation/choke in the upper rev range (no custom tune other than CSL tune to accommodate for the headers). I wanted to see if anybody else have ran similar tests and if I should should reach out to Karbonius themselves? Another question I have, what type of impact would this have with unmetered air being sucked in, if any?

​​​​​​​https://www.youtube.com/shorts/ZXj6H5ul5HM

[3002 tii]

I think it’s interesting that Karbonius goes out of their way to to describe the OEM airbox option as no performance gains, just sound only (unlike their race version). If that’s the case, between that, minor fitment issues and now QA issues, it’s even less compelling for me.

[wdb]

Originally Posted by Jdmaflac

Found out in the shared video that both bottom corners of the airbox itself leaks, granted the engine doesn't throw any lean codes but I feel like there's a slight hesitation/choke in the upper rev range (no custom tune other than CSL tune to accommodate for the headers). I wanted to see if anybody else have ran similar tests and if I should should reach out to Karbonius themselves? Another question I have, what type of impact would this have with unmetered air being sucked in, if any?

​​​​​​​https://www.youtube.com/shorts/ZXj6H5ul5HM

Not good! Those seams need to be sealed somehow.

[maupineda]

Sharing my thoughts

I had this concern when I inspected my box, and I was 90% certain it was not air tight, that said, my car has been custom map and I don’t notice any issues, but my map for sure addresses any extra air via fuel trims, and all within the ecu failsafe as I don’t have any check engine light, even before mapping. I also noticed zero change in performance from my CSL Karb, so I am sure I am not missing anything other than the wonderful sound, but I also no longer have the lumpinesses I had with the CSL setup.

that said I kept my CSL and OE air box if I ever want to go back to either

[onebluemcm]

Resurrecting an old thread.

I would assume, if they haven't addressed the air tightness issues of this box that you could go in through the main inlet and apply some fiberglass/CF resin to seal it up, does that sound reasonable?

And just to be clear, they didn't make 2 versions of this, one for E46 M3 and one for Z4M, correct? I saw where one vendor lists it for E46 M3 but says it isn't compatible with Z4M, which I think is false if I'm not mistaken.

While I'm at it, any updates? Been going back and forth between this + Eventuri filter housing or a full CSL style intake, I'm leaning this way mainly to stay with MAF-based system. If anyone has done any tuning with this combo, please mention what you did, how it went. Thx.

[maupineda]

You can find all those answers in this thread

Also, they have addressed this issue for new air boxes.

[onebluemcm]

Man, I've been through this entire thread and other threads on the subject multiple times. I'm going to assume sealing any leaks with resin would be possible, but I didn't see anywhere where someone actually did that. But if it's fixed, which also isn't mentioned in this particular thread until you said it, it's a moot point I guess.

Did you just stick with your tread grip tape solution for the elbow or did you end up installing the epoxy-in ring fix they came up with?

[MBan]

I haven't leak-tested by plenum but data logs don't show any weird values and the car runs perfectly. I've also taken the plastic elbow off and on a bunch of times with the new lip on the plenum opening and it hasn't moved a bit. This is after 6 months, so lots of heat cycles.

There is just one version of this plenum. It was tested on an E46 M3 during development, but also fits the Z4M. One thing to note is that the installation in the Z4 is much more 'compact' and there is very little (say 3mm) clearance between the plenum and the rear left corner of the standard airbox lid. I checked again last weekend and it is super close. No problem with an Eventuri, of course.

[onebluemcm]

Thanks for that MBan. For now, starting with Eventuri and a tune. I figure this is the best combination of increased sound and performance for the money. The carbon box sure would be nice, but to my understanding it's an aesthetic thing (sound + appearance) primarily, and I'm not discounting that, I just think for now and my goals, I'll keep the $1600 in my pocket.

I found that Rouge makes a Z4M specific silicone elbow with the side port like the OE elbow, it's a little pricey but thought I'd see how it fits. Also have euro headers that I've been contemplating installing for a long, long time. I may give that a go along with the Eventuri and tune at this time. Tuners, like Josh/Severn, can tune out the secondary O2 sensors, yes? I have no problem getting bungs welded in to my mid section, will have to for the EGT anyway, it's going to have to go somewhere.

[MBan]

Definitely reach out to Josh to get advice on the tune 🙂