I was taking a look at the snorkel intake on my MCS and noticed that instead of it being a hose that goes directly form the front grill to the air box, there is a small portion that points towards the bottom of the engine compartment. At first I thought this was a water drain hole in case water got into the snorkel. Howver this seemed unlikely since it doesn't seem likely that water could get in there, even in monsoon rainstorms and and there was no hole for the water to drain out (at least I could not feel one).

I know the BMW engineers put it in there for a reason (even if it was not a good one from a performance standpoint ) but I am curious as to why it was designed that way and not just a hose straight from the grill to the air box.

 

I believe I've read that that's an air chamber to make sure there's enough air on hand for the supercharger when you suddenly accelerate.

 

I asked an MA about that and for the MINIs there are a few extra turns and twists that might be in the air intake inlet hose to allow for optimal air flow/movement for the system to work. I think they had looked at airflow and found that the pattern they used to work the best given the path of air to the intake.

Does it allow for some spare air for the SC in case you need it? Well in a truely close system that might be true but with all the aftermarket open intakes then that would less the case. Then the other question would be given the altered air intake system- should a more direct hose work any better-maybe a silicon hose with the least restrictive air flow design just as the alta hose works from the air intake to the throttlebody.

 

do a search using "resonator."

there is a long thread here or on mini2 suggesting that this dangling thing is a resonator box to quiet the intake noise.

 

flyboy is right - the various tubes on the intake snorkel is for shaping the sound. You've heard of DSP, well, the tubes are more like Analog signal (sound) processing When we add a cold-air intake, I'm sure the sound engineers are spinning in their cubicles

 

I don't buy the idea of that pocket being an "extra supply" of air for when you slam on the gas. As was stated above, this is an open system, if the car needs more air it will get it via the grill or windshield cowl.

On the other hand, the resonator idea sounds more reasonable. Automotive engineers for years, including BMW, have designed their intake systems to be quiet for the "average" consumer. Unfortunately, designing a quiet intake is almost always at the sacrifice of maximum performance.

If that is the case, it would be nice is somebody like Alta could also design a nice silicone hose piece to replace the stock one. Although given a choice, the hose from the filter to the throttle body is definitely the more important one of the two hoses. Personally, I think the more cool air you can get to the filter (in particular an aftermarket cone filter setup) the better.

 

The extra tube on the duct is definitely a resonator. When the manufacturers go through certification for EPA/DOT specifications all of the vehicles noise emissions have to be below the standard (80 Db ?). This includes exhaust noise, engine mechanical noise, and intake noise. Most manufacturers utilize some form of a Helmholtz resonator design to tune the intake noise to meet those standards. It works by bouncing a pulse of air back into the intake path exactly 180 degrees out of phase with a noise pulse reflected by the closing intake valve. On some cars (like the early 90's Mustangs) it can be restrictive and removing the resonator improves performance. The design of the Cooper S's intake duct doesn't appear to be very restrictive and modifying the duct would probably just change tone of the intake's sound.

 

Interesting article on the cover of the New York Times on Saturday; mostly it talked about the development of smells that US manufacturers are using to make their cars more desirable (especially Cadillac). It also talked about how much they are relying on sound engineers to give their cars a very specific sound...mostly they are making the engines resonate MORE (e.g. Ford F-150).

What's interesting is that BMW was quoted in the article and they said (re: smells) that they are most concerned with making sure that there are NO smells in the car--that it smells fresh and new (i.e. no weird chemical smells, like those from industrial glues and whatnot). I would suspect that this would also extend to the resonation thing--BMW is most concerned with elminating excess sounds as much as possible, and hence that bizarre resonation tube.

 

I am also pretty sure it is a Helmholtz resonator. My 325i has it also.
Its shape may not be designed purely to reduce noise. Knowing BMW, it is possible that there is a certain acoustic signature they are going after, and the Helmholtz resonator is designed to tune the noise our MINIs produce.

Z4s have a tube that actually ducts the noise into the cabin. If you ever look under the hood of a Z4, look for it on the driver's side of the engine. It is bright red in color.