Just out of curiosity, can anybody tell me the serving purpose of the downtube that is between the intake behind the grille and the air box on a stock system?
I'll post a pic if anyone needs clarity.

 

Someone once told me, it was to decrease the sound of the SC whine.

This was a long time ago, as he installed my "heat seated" 15% reduction pulley.

Could it be to collect small amounts of water?

 

My educated guess is that it is a "quarter wave resonator"
http://www.diracdelta.co.uk/science/...be/source.html

Basically it's tuned to cancel out sound at a specific frequency. The intake must resonate at some specific frequency that the MINI engineers felt was unplesant to listen to. The same concept can be used in the exhaust system as well, I've contemplated building a 1/4 wave resonator to cancel out the drone from my magnaflow at 3000 rpms.


Jason

 

Very interesting.
I wanted to make sure it wasn't open at the end and sucking up hot air from the engine bay.
Thanks Guys!

 

I removed both this pipe and the little pipe on the side that turns out and back into the intake tube to the airbox. I then wrapped the now-naked tube with CF. Looks cool and works as well as before. No appreciable difference in sound at any frequency.
cheers,

 

Isn't it a drain tube for rain and snow that may go in there? Is this down tube drilled at the bottom for drainage? I can't remember...

 

I was always told the tube is to collect water and keep it from getting into the engine. Thats why it goes down for several inches to collect water.

 

Interesting question, as I was poking around under the bonnet of my new '06 MSCa last night and noticed this tube... my first thought was that it was a drainage tube in case of accidental water ingestion. That was my last thought, too. I haven't traced the tube to the undercarriage in order to see if the end of it is open (to allow free flow of water drainage) or if it is sealed at the bottom. I'm inclined to say it is open. Never thought it had anything to do with resonating frequency noise cancellation...but hey, anything's possible... it's a MINI.


rock on,

-boognish

 

Mine is not open on the bottom, although it has a very small hole (less than 1/8"), I would imagine that the purpose of that small hole is to prevent the "downtube" from storing water, but it's not going to do much if I decide to go puddle jumping :-P


Jason

 

the tube has no purpose other than to decrease the humming/whistling/resonating sounds that may be produce from the intake system. it does have a really small opening at the bottom just in case any kind of fluid gets in there.