"In this Special Series, I document my CSL airbox experiences. I take you into my unboxing of my various airboxes, the hardware checklist, the tuning dilemma, installation notes and my driving impressions with proper sound clips.

In this entry, I discuss why CSL airboxes from many brands have had failures, why this one is promised not to."
-Matt

The main failure point: trumpets.

In my research on CSL airboxes, there have many stories about failing air boxes from various brands causing catastrophic engine failures.

The culprits often come back to failing adhesives on the multiple fittings on and within the airbox.

It takes one to know one.

I’ve been watching Antonio bring to market his E9X plenum, explaining every step of the R&D process. I didn’t immediately reach out when it was released, as I was aware of the history on previous CSL airboxes that had quality issues.

Since then, 50+ carbon plenums were delivered to S65 owners with great reviews. 

I’ve chatted at length with Antonio on the backstory, and found what I believe to be an BMW M enthusiast that made things right.

He put his money where his mouth was and went into debt to cover a recall campaign. It was back to the drawing board to revise the trumpet fixation design.

Over 200+ CSL airboxes have been delivered since. 

Engineering for reliability.

CNC'ed fittings. 

Upon careful examination of the airbox, you will find all bolt threads, bungs, alignment pins, snorkel ring, brackets and most importantly the ITB fittings are made from CNC'ed aluminum.

The only non-aluminum brackets are the 2x carbon brackets by the side wall to route hoses.

Aviation grade adhesives. 

The trumpets and sensor bungs are adhered with aviation grade adhesive specifically picked to handle the harmonic vibrations the carbon airbox generates on the S54.

They also thread locked with a custom nut on the outside.

No support beams. 

Antonio deleted the thin carbon support beams from the OEM design as these were a source of failure on other boxes. They were fitted by the trumpets to improve rigidity. 

Haimus deemed their design sufficiently rigid to do without, and eliminated this potential failure point.

The wet rivets.

The carbon trumpets are "wet riveted" for durability. In simple terms, the trumpets are slid through the threaded CNC'ed cups with excess adhesives during their assembly.

That excess spills out from holes in the CNC'ed cups to reach the optimal amount required.

It creates the metal fittings that slides on the ITBs and rubber hoses. A metal ring is then threaded locked to the cup protruding from the airbox.

Let's talk trumpets.

While first thought of by many as a musical instrument for the S54, the CSL airbox developed by BMW M was first and foremost a performance product.

The booklet that came with the Haimus Racing CSL airbox was provided in-depth information and diagrams about what makes this box purposely developed for reliable performance.

The insides of the carbon airbox is smoothed out to reduce turbulence, including the signature carbon trumpets of these boxes.

Enhanced dimensions. 

Dimensions are changed to enhance the with the stock CSL airbox to slightly augment the radius of the bell curve.

You can visibly notice the curved edges of each trumpets.

Vacuum effects. 

The altered trumpets help create a vacuum effect at 3000 and at 7000 RPM. Haimus claims they create more midrange power then any OEM CSL replica airbox from 3000 to 7500 rpm. They further claims this allows for direct airflow, bumping up power levels in the mid to top-end of the RPM range.

Trumpets 5 and 6 are placed further back and slightly shorter.

Whether or not I'll feel it doesn't matter much to me. It's a nice plus to know you're rocking the best performing airbox there is.