what is this for? (pic of engine attached)

[300HURST]

Its part of the airbox but what does it do? I don't even know what its called. Its too small to keep air in it.

http://i112.photobucket.com/albums/n196/northcoast300h/DSCI0262.jpg

[FiretruckRedBMW]

Its just a tiny compartment designed to heat the air up before throwing it into the engine. Its got an opening right after the air filter. Its simply gathers engine heat and keeps our notoriously cold running engines not running as cold in the winter.

[pussiwillow]

hell i live in arizona and have no use for that as our temps in winter rarely fall below 40, does removing it yield anything?

[shogun]

leave it as it is, if BMW would have thought they can save money by eliminating it w/o any probs, it would not be there.

[pussiwillow]

well like he said its for the cold, alot of people live in the cold so bmw put it there to accommodate everyone, i dont live in the cold so i wanted to know if it would yield any gains, why do i want to suck warm air in the engine when not needed?

[300HURST]

Thanks everyone...never saw one like this. Kind of a bad design. I can't see a thermostat built in. These are made to heat up the car as soon as possible for better performance/MPG while engine is cold. Its been used on many cars since the 50's , but back then they had exhaust manifold "riser tubes" that would direct the hot air into the intake. I have it on my '70 Hurst. They all had thermostats on them. Once the car reached 180 degrees, the thermostats would flip a damper in the air filter housing shutting off the hot air and opening the normal cool air openings. Worked great when new but the thermostat plates always corroded up and then the car constantly got hot air which ruins performance once the engine was heated up. Cold air is your friend when the engine is heated up.

I don't know about your car but mine accelerates much faster in 40-70 degree weather than over 80 degree weather. If I lived in Arizona, I would take it off and plug it up. Its easy to do by just pulling it off and you can always put it back on. I would also insulate the airbox and maybe fog the airbox to the brake duct too. BMW's were made to satisfy all climates like Germany....and Cleveland! -10 in winter, 98 degrees in summer this year!

[pussiwillow]

hell ya time for experimenting

[300HURST]

Ya, I'd like to take mine off too since my engine gets to 195 degrees within 3 miles over 50 degrees. But since I fogged my airbox this summer, it might take longer below 50 degrees. I'll have to wait and see what happens this winter.

[Joylove]

The hot wire in the MAF detects the air density which is directly proportional to the temperature.

[wbarfels]

Kind of makes you wonder about everybody getting cold air intakes

[dieselbro]

Part number 4 in this diagram, REALOEM lists it as a resonator so I would assume it keeps the intake quieter?!?

http://www.realoem.com/bmw/showparts.do?model=BE73&mospid=47481&btnr=13_0417&hg=13&fg=20

http://www.realoem.com/bmw/diagrams/v/x/30.png

[FiretruckRedBMW]

It probably keeps it quieter as well. For the AZ people, I would at least experiment by taking off the top intake and taping off the hole and at least see if it makes any difference, it might or it might not. I wouldn't rip the thing off there in case you decide that it runs better with it on.

[jmo69]

I don't know about your car but mine accelerates much faster in 40-70 degree weather than over 80 degree weather.
Everybody's car does, it's basic physics, colder air is denser, more air in the same space, more performance.