Levelling up.

Levelling up.

"These build journal entries are part of a Special Series on the development of the S85 CSL Style Carbon Plenum and S85 CSL Competition Complete Carbon Intake System and written in collaboration with the design & engineering at Infinity Design.

In this entry, I get my hands on the 3D printed prototypes of the upcoming S85 CSL Competition Complete Carbon Intake System. I provide insights into the target specifications by reviewing the CAD designs and lay down my expectations of the kit. 

Stay levelling up."
- Matt

A refresher.

In early 2022, I got with Sal @ InfinityDesign to develop the first reimagination of the CSL prototype carbon fiber plenum.

The engineering team at Infinity Design tackled this development project with a key focus on modularity. 

The side inlets, lid and trumpets are all bolted to the main plenum body. 

The intentions with the OE+ plenum.

The first variant brought to market was the OE+ plenum. It was designed to work with stock or any aftermarket intake system. 

Additionally, it can work with MAF engine mapping when specifically calibrated for. This was especially critical to those registered in juridictions with such emissions requirements. If you do not, my recommendation is to go the AlphaN route immediately. 

The OE+ variant is additionally intended for S85 owners across various chassis swaps.  

I received and installed the pre-production unit in September. After much testing and final production adjustments, the first 25x units from the crowdfunding will now all have been delivered.  

The new sounds from 4,000 to 6,000 RPM are godly and CSL'esque. The overall increase in sound is just right for an M5.  


A few of us M5 & M6 V10 wanted more: we wanted the original.

Back in May 2022, I published a journal entry documenting my deductions from the CSL prototype images we had dating back to 2009. 

Those deductions were initial inspiration to the entire project. The OE+ variant didn't get us there just yet. 

A screenshot from the past. 

Reimagining the original BMW CSL prototype.

The Competition variant will take inspiration from the original CSL prototype and build upon the knowledge acquired in the design of the Sealed Carbon Intakes and the OE+ variant of the S85 CSL plenum.

The original CAD designs for the Competition variant. 


 Looking like a world champion arm wrestler. 



It will have much larger air volume.

The end goal is to have up to 20% higher air volume across the entire intake system. 

The standard inlet tube of the sealed carbon intakes versus the 3D printed inlet tubes of the Competition spec.  


The inlet tubes have matching, enlarged side inlets for the plenum. 


It will retain state-of-the-art venturi effect.

The sealed carbon intakes retain the use of the coned shaped filter, letting the larger inlet tubes dictate air flow. 

This is where we can assume the design veers off from the OEM prototype airbox design.

I documented the foundations to the development of sealed carbon intakes in a journal entry covering why BMW M sealed their intakes and how the V10 system has been improved upon with the sealed carbon intakes.



It will have velocity stacks instead of trumpets 

The higher volume of air will be tested with shorter velocity stacks. The shorter stacks are documented to support higher performance gains at high RPMs. 

The prototype stacks are printed from nylon. The productions stacks will be carbon or spun aluminum - it's TBD.

[...] that will likely make more power at higher RPMs 

Like most "breathing" upgrades on S85, I'm expecting some gains from 4,000 RPM. 

What happens beyond 7,000 - I'm eager to find out.

This may reopen the debate on the usefulness of 292 cams on the S85. It's already been happening for the S65. 

and it will run on pure AlphaN without any rewiring. 

Sal will be including a specific engine map using AlphaN. 

Contrary to the standard Carbon Sealed Intakes, the larger inlets will not have MAF bungs to optimize for space.

A new pair Intake Air Temperature sensors will be required and included along with the wiring and connectors.



You will be able to upgrade from your current sealed intakes and/or OE+ variant plenum. 

You will retain the lower housing, filter element and clamps of the sealed carbon intakes, along with the carbon plenum body. 

I test fitted the inlet tube on the lower housing. The clamp fits like the previous carbon production units. 


Up next: I update this entry with my final test fitment, and we get the molds started for the pre-production road and dyno testing. 

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