[HyperM3]

Ok, so I was in the mood to start taking things apart after I finished my CDV replacement.

Opened the airbox and now I have a hunkering for a tinkering.

Please refer to picture 1. You can see the direction of the flow of air to the intake. Chamber number 1 receives it from the (technically)cold intake to the kidneys. Then it swirls around and up through the filter and into chamber number 2. There you can see the flow of air goes two ways.

Now, refer to picture 2. As you can see here with the top of the airbox flipped over, there are several plastic grooves. With this top on, there may be only about 1-1.5 inches of room for the air to go into the second chamber. In my head, I can only see how this might slow the air down or hold back the volume of air that can move into the second chamber.

Im thinking about removing these slats (see boxed and X'd part in picture 2) so that it might unrestrict it a bit. I think this might increase the noise as well.

My counterthinking to this is that WITH the grooves in there, it keeps the air moving smoothly to the other chamber. Without the grooves the air might bounce around more and be less directed.

Any thoughts?

[rpiopio]

Well, those fins look like they're pretty specifically placed. I'd imagine they do direct the airflow in a smooth line to minimize turbulence.

I have to believe BMW engineered those fins in their CAD. Structurally, those lateral fins would have only been used to support the roof of the case from falling in under the negative air pressure, but I'm sure that support could have been achieved with fewer fins. That leads me to believe they are there for more reasons than structural support.

[Rawhyde]

Originally Posted by rpiopio

Well, those fins look like they're pretty specifically placed. I'd imagine they do direct the airflow in a smooth line to minimize turbulence.

I have to believe BMW engineered those fins in their CAD. Structurally, those lateral fins would have only been used to support the roof of the case from falling in under the negative air pressure, but I'm sure that support could have been achieved with fewer fins. That leads me to believe they are there for more reasons than structural support.

I agree. I bet they're there to promote more laminar airflow. I'd leave them alone.

Rawhyde

[Chesmu]

removal of hose fins would probably be fairly "dirty" and might lead to plastic bits flying into your engine. If you're that much interested in improving the intake, safely invest in a Simota (is the used one still for sale?) or a GM replica.

Just my .02

[gary328xi]

Those fins straighten the air out preventing votices.

[turbocoins]

I think that you'll create more turbulent airflow if you remove them. Plus, I don't think that you'll actually get any more air in, since the slats are within the airbox. I wouldn't do it.

[HyperM3]

That being said, BMW has also been known to do things like this to keep the intake noise down. Most manufacturers employ some sort of ducting that when removed, you can REALLY hear the intake. Im wondering if this was part of the design.

You have to think, if you have an open element cone filter, you dont have any fins leading air to it. It gets bombarded by turbulent air.

[itsbrokeagain]

+3. I'd leave it alone for the time being. I think its going to be hard for an intake kit to be produced for this car...

[HyperM3]

Originally Posted by Chesmu

removal of hose fins would probably be fairly "dirty" and might lead to plastic bits flying into your engine. If you're that much interested in improving the intake, safely invest in a Simota (is the used one still for sale?) or a GM replica.

Just my .02

There are no intakes made yet for the 335. Secondly, its not like I was going to cut the intake while over the engine. If I use my dremel properly there wont be any bits left to go into my engine.

[caesardog217]

I would leave it alone, its there for a reason. But what do I know

[HyperM3]

Originally Posted by caesardog217

I would leave it alone, its there for a reason.

While I do agree with this philosophy, I have to argue against it.

If we all believed that things were there for a reason, we:

Wouldnt swap out the RFT's.
Wouldnt change the CDV.
Wouldnt install any aftermarket intake.
Wouldnt install any ECU type tuning.
Wouldnt put on new exhaust.
Wouldnt shorten the shifter.
Wouldnt go against BMW's recommendation of oil change intervals.
Woudnt adhere to the 1200 mile breakin.

The wouldnts could keep on going.

[caesardog217]

I see your point

[BoostedBMW]

I'm not sure what to think here because part of me thinks that the slats might be helpful with airflow, but the other part of me thinks that they are there to keep the intake noise down. Hmmm.... I wouldn't worry about the plastic bits going into the engine though, there is no way they could get passed the turbo's and throught the intercooler (not that you would want plastic pieces in your turbine/compressor wheels). If for nothing else, I want an aftermarket intake to come out for this car so that I will have some damn space in the engine bay, that thing is HUGE!

[Chi-town330]

I am an (ex) aerospace engineer, in my past life spent a decade on the F-16 and F-22 programs, and dealt with aerodynamics, loads, stress analysis, and flight test.

and I don't have a clue. . seriously.

there, wasn't I helpful?

more seriously though, I don't understand why you feel removing the fins will help? The fins take up just a few percent of total cross sectional area, so I don't see an appreciable gain there. The flow clearly has to take some serious turns, and the fins would help straighten the flow, so could possibly see some potential use. But I have no idea of the flow velocities in that space, the pressure gradient across the structure, what really happens to the flow once it gets into the turbocharger, etc.

So my whole point (other than wasting people's time while I watch Sanjaya hopefully get booted off American Idol) is that I don't see much upside potential, and do see some downside risk. i.e., i don't see gains, but do see the possibility of less efficient flow entering the turbos. But not convinced that would be an appreciable issue, either, although i admit much ignorance here. if the pressure in that chamber does drop significantly from 1 ATM, the one prior poster might be right in that at least a few fins would be wise to prevent bowing inward, but again, just a possibility, depending on the pressure delta inside vs. outside that chamber.

I just don't see the upside here.

there is a "splitter plate" at the entrance to the F-16 engine, as well as many others, but that is really for different reasons - removal of low velocity boundary layer flow that built up along the underbody on the way to the inlet. That leaves higher velocity air for the engine, which jet engines thrive on.


Creative thinking on your part, though, I must admit. And I am not saying you aren't on to something. pretty interesting post!

[purplewidow]

Originally Posted by Rawhyde

I agree. I bet they're there to promote more laminar airflow. I'd leave them alone.

Rawhyde

i totally agree...why else would they go to all the trouble!!!
________
FAKE WEED

[Deveray]

Great post Chi-Town... enough expertise to own up to not knowing!

[AndreTheGeek]

A lot of the time these things are to muffle the sound. I suspect that they don't impede much airflow, since the tuners on the board seem to be able to suck enough air to get 350+ HP with a Procede or Turbo Tuner.

[iatacs19]

cut it then vacuum the bits should be ok. Those baffles are there to decrease the intake sound like another poster mentioned. Honestly you won't notice any performance difference maybe 4-5hp at most.

[Tag]

Get the part number off the lid and if it's not that expensive go ahead with your experiment and cut off the fins. If you don't like it order another lid.

That said I think this is a complete waste of time...

[lkraven]

Originally Posted by HyperM3

While I do agree with this philosophy, I have to argue against it.

If we all believed that things were there for a reason, we:

Wouldnt swap out the RFT's.
Wouldnt change the CDV.
Wouldnt install any aftermarket intake.
Wouldnt install any ECU type tuning.
Wouldnt put on new exhaust.
Wouldnt shorten the shifter.
Wouldnt go against BMW's recommendation of oil change intervals.
Woudnt adhere to the 1200 mile breakin.

The wouldnts could keep on going.

RFTs are there in case you get a flat. Some people are okay with that risk for the daily reward of nonRFTs.

CDV is there to protect driveline. Some people are okay with improved clutch response and less safety.

Stock intake makes performance compromises for noise and cost effective manufacturing. Some people are okay with increased expense and noise for performance.

Stock ECU program is a compromise for EPA fuel efficiency, emissions, and drivability for the luxury type. Some people are okay with reduced efficiency, and emissions issues for more power.

Stock exhaust is engineered for manufacturing cost effectiveness and lower noise level. Some people want more noise, and more performance, at a cost premium.

Stock shifter is accessible weight and throw for tooling around town. Short shifter increases required force due to levering mechanical advantage reduction, but some people are okay with it for the shorter, more precise throw.

Oil change intervals are to reduce costs. Some people would rather play it safe, and are okay with an increase in costs for a perceived increase in engine reliability.

1200 mile break-in -- I'm not even touching this one.

However, point is, you don't know what the fins are. Removing them WITHOUT knowing what they're there for is an experiment that can go awry. All your previous examples are (mostly) known equations, and people can opt to switch one set of compromises for another. Dremeling a set of fins the purpose of which is unknown is not remotely the same thing as swapping out RFTs for non-RFTs.

I advise you to leave the fins alone.

If not, then post a DIY.

[STE92VE]

Originally Posted by HyperM3

While I do agree with this philosophy, I have to argue against it.

If we all believed that things were there for a reason, we:

Wouldnt swap out the RFT's.
Wouldnt change the CDV.
Wouldnt install any aftermarket intake.
Wouldnt install any ECU type tuning.
Wouldnt put on new exhaust.
Wouldnt shorten the shifter.

Sounds like bone stock to me which is really not a bad thing.....maybe not as good as some mods, but certainly not terrible.

Notice that the fins on the air box cover match up with the ones on the lower, so I would agree they are there to effect air flow.

Now if you came up with a CAI......

[TMNT]

To me they look like they help keep the filter in place/restrict movement, or prevent buckling when driving. Any movement that would result in the fliter lifting up without those "barriers" would risk particles being ingested into the intake manifold.

Again, I dont own a 335i so I don't know if there are clamps holding the filter in place or not, but from the pictures it looks like there isn't. But the again the actual intake cover could act as a seal with the filter via male and female ribbings.

Question: Are those slats molded to the very top of the intake cover or are the suspended in air between the bottom and top of the intake cover?