Air box - BMW Forum

PhatCat · 09-12-2006, 01:00 PM

Hey all. I swapped the old stock style air filter in my car for a nice, high flow K&N and noticed the difference immediately. The thing I am wondering is if any difference would be noticed if I were to remove the 'snorkel' from inside the air box that is attached to the Mass Air Meter. There is only a gap of a couple of cm's between the tip of the snorkel and the wall of the airbox. Would pulling that thing out of there be less restricting for the airflow into the MAFM, or is it there to smooth the flow into the MAFM?

PhatCat · 09-12-2006, 01:04 PM

Haha...my bad, air mass meter!

Starmavin · 09-12-2006, 06:42 PM

That is there to help prevent air from swirling into the meter and flow into it in a more uniform manner. But as far as performance goes, I haven't seen any proof in either direction.

triggrhaapi · 09-12-2006, 06:43 PM

It will make a difference.

JoeMadoo · 09-13-2006, 12:19 AM

Air Flow Meter

PhatCat · 09-13-2006, 09:35 AM

Sounds like it might be best to leave it in there, uniform flow is better than marginally higher and turbulent!

gotKRAUT · 09-13-2006, 04:42 PM

yup, but then again turbulance also helps with atomization of fuel but you want that to happen closer to the combustion chamber because it will also slow the flow

double edged sword

nukeduster · 09-13-2006, 05:19 PM

turbulent doesnt matter with an afm.. the vane will open the same ammount regardless as to wether its turbulent or not.

i removed mine on my eta, felt a difference after i put the chip in.

triggrhaapi · 09-14-2006, 12:13 AM

Quote:

Originally Posted by PhatCat

Sounds like it might be best to leave it in there, uniform flow is better than marginally higher and turbulent!

No no no no no no no no. You're thinking of laminar flow through a pipe, which is true, with laminar flow, you have a thinner boundary layer and faster travel through the pipe, but that does not apply to an engine intake because you want turbulence, so you have a rough intake runner in the head itself with a lip to act as a vortex generator. For a car intake, you want greatest flow through the intake possible, because the intake is running on vacuum and small changes make a big difference when your highest pressure is ambient only (14.7psi worth of flow if you have a full vacuum, which isn't much really and that's at sealevel) because you really have a massive pressure cap, so you can't cram to get your flow, you have to go bigger and less restricted, turbulence doesn't cause much damage to a low pressure flow in a fat 3" pipe.

PhatCat · 09-14-2006, 09:51 AM

Some great points you have all brought up...maybe it will come off after-all. Maybe I'll pull it off when my chip shows up(still eagerly awaiting it's arrival). Cheers guys.B)