Which csl airbox to buy?

[T.J.]

I do.

What is its story?

[Obioban]

What is its story?

The company (Die Wethje) that used to make CSL airboxes for BMW also made them for other companies. Back in the early 2000s, they made a version with the race style duct. Evolve bought one of those a decade later, after it was no longer being sold, copied it, and started selling it. I got the OEM one from evolve that they copied to make their own.

So, OEM (original equipment manufacturer) CSL airbox with race style ducting

[Grke46m3]

Does anyone have pictures of the Karb race box installed?

[x Spades x]

And the evolve box is a copy of the oem box I’m running.

IMO the best thing about the flap is that it looks stock. If I had one, I’d code it to be open 100% of the time, as every dyno I’ve seen has it closed only hurting power.

If you don’t mind the not stock look, and are going to run it open, the evolve/karbonius race makes sense imo... which is why I’m running it (albeit the oem version).

The flap is mainly used for low end driveability (box vaccuum - consistent throttle response), low end torque. When I installed my flap, it was a noticeable difference. I have the flap opening at 5.5k 1st gears, 3.5 2and gear, and 2.5 all other gears.

[x Spades x]

Interested in hearing thoughts on this as well. Between Karbonius and Evolve are there any big differences or just splitting hairs? Considering one doesn't intend to run the flap?

I've had both (with 288/280 cams) and dyno'd. See below link

https://nam3forum.com/forums/forum/main-forum/e46-2001-2006/1925-s54-dyno-database/page5

[bassel_sy]

Does anyone have pictures of the Karb race box installed?

been waiting 2 months for mine

[Obioban]

The flap is mainly used for low end driveability (box vaccuum - consistent throttle response), low end torque. When I installed my flap, it was a noticeable difference. I have the flap opening at 5.5k 1st gears, 3.5 2and gear, and 2.5 all other gears.

Certainly not for torque-- every dyno I've even seen posted shows the engine making less horsepower and torque with the flap closed than open (when tested same car same dyno with/without flap).

Drivability... I've never noticed any difference. Hard to imagine a snap change (as there's no way to modulate the speed of the flap opening) improving drivability

[usdmej]

Karbonius and other companies (TMS) have either improved upon or changed the design for better airflow.

the changes Karbonius has made over the years seem to address their own mfg issues more than make any improvement over an oe box

Can't speak on turners box claims but their graph claiming gains over oe was suspect to say the least

[usdmej]

every dyno I've even seen posted shows the engine making less horsepower and torque with the flap closed than open

why would you even run a Dyno with the flap closed? That's not how it was designed to function in the first place?

In partial throttle low rpm driving driveability is noticeably better with the flap closed

[ATB88]

the changes Karbonius has made over the years seem to address their own mfg issues more than make any improvement over an oe box

Can't speak on turners box claims but their graph claiming gains over oe was suspect to say the least

Actual proof of benefits in TMS's design absolutely remain to be proven. But Karbonius themselves say "2- Diameter and shape of the trumpets modified, 51,5 mm diameter instead 50 mm and a round shape on the front of the trumpets contributes to a better airflow inside the engine. 3- Exclusive 6th trumpet design, the 6th trumpets it´s the less air gets , so we redesigned the shape of this trumpet to get more air and we constated 1hp gain with this modification." (from https://karbonius.net/producto/bmw-m...ox-fullcarbon/)

Not saying these are groundbreaking changes/gains, but, if it's even *somewhat* improved over the OE piece and looks identical, I would take the Karb over OE even if their costs were in the same ballpark. That's just me.

[Cubieman]

I can attest to an increase in driveability after installing the flap. In low RPM (sub 3.5k) it does feel like it pulls a bit better with the flap closed. It isn't a night and day difference, but I certainly noticed a difference after expecting not to feel any difference whatsoever after install.

[Obioban]

why would you even run a Dyno with the flap closed? That's not how it was designed to function in the first place?

To see if it helps or hinders hp/torque at low rpm.

[usdmej]

To see if it helps or hinders hp/torque at low rpm.

the flap appears to be designed to aide in lower rpm driveability. running a full throttle dyno run at low rpm with the flap opened and closed to show changes in power doesn't speak to any claims over whether or not driveability is improved or not.

I personally very much prefer running with a functional flap since getting on the throttle aggressively at lower rpm doesnt result in as loud of an airbox sound. the level of acceleration becomes commensurate with the volume the airbox is putting out. i can't personally say i care that i'm accelerating a little bit slower at lower rpm compared to if the flap was open. i consider that an improvement in driveability

from others experiences, it seems like running an airbox/flap without the full OE CSL ducting lessens volume delta so ymmv

[Obioban]

the flap appears to be designed to aide in lower rpm driveability. running a full throttle dyno run at low rpm with the flap opened and closed to show changes in power doesn't speak to any claims over whether or not driveability is improved or not.

I personally very much prefer running with a functional flap since getting on the throttle aggressively at lower rpm doesnt result in as loud of an airbox sound. the level of acceleration becomes commensurate with the volume the airbox is putting out. i can't personally say i care that i'm accelerating a little bit slower at lower rpm compared to if the flap was open. i consider that an improvement in driveability

from others experiences, it seems like running an airbox/flap without the full OE CSL ducting lessens volume delta so ymmv

Ah, if by drivability you meant noise to power ratio, I agree-- the airbox is loud at WOT low RPM despite the car not being very fast at low RPM. I don't really WOT at low RPM and it's not loud when not WOTing, so I don't really see that as a concern.

I assumed you meant something like throttle response when you said drivability.

[Ramps]

It would be interesting to see if part throttle dyno runs with the flap open and closed were the same or different. If the engine makes more tq at low rpm at part throttle with the flap closed vs open it certainly would feel faster even if it’s the same or less power at full throttle. Most people don’t drive full throttle at 2500rpm.