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10-03-2022, 04:38 PM | #1 |
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How important is the air straightener?
The stock filter box on a Z4M has what appears to be an air straightener just before the Maf sensor.
I have the aFe shroud, filter and Maf housing and it has no straightener of any kind, the induction sound is better for sure and regardless of aFe's claim of an additional 15 hp I don't think it really adds any extra power at all. So just wondering if the straightening out of the the turbulent air makes a difference to power gain or Maf sensor accuracy. I have also heard that the what I'm calling the air straightener is a baffle to tumble the air and silence the induction sound from the TBs Thanks
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10-04-2022, 10:21 AM | #2 |
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I would think it is there to stir things up, rather than 'straighten' them. Turbulent air is a good thing, I think, when one is trying to mix it with combustible stuff. Also I doubt the BMW engineers would have put it there for no reason. As for it being a silencer, they added a 'sound tube' to the N52 cars to increase induction noise in the cabin, so again it doesn't make a lot of sense to me that they'd want a quieter M.
Realoem isn't much help -- the whole air cleaner housing is listed as one part number. Although they do call it an "intake muffler"! |
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10-04-2022, 10:42 AM | #3 |
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From my experience and what I have been told, you want a minimum of 4" of "straight " flow of air before your MAF.
This might not be applicable or attainable in your scenario, but you want as much straight air as possible. I agree BMW put that piece in there for good reason. Without it I would imagine the readings at the MAF would be erratic from the turbulent air.
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10-04-2022, 04:19 PM | #4 | |
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Quote:
The screen and the plastic grid in front of it I think will smooth out the air so the Maf can get an accurate reading but it will also muffle the sound of induction. As wdb mentions above, Bmw calls it a muffler, the German translates to silencer.
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10-04-2022, 05:28 PM | #5 |
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The "muffler" or "silencer" refers to the entire air box assembly. The majority of the "silencing" is accomplished by the shape of the box and the 2 filters in it (carbon + paper). Whether that screen is to straighten or stir things up can be up for debate, but the gist of it is that it is there to create consistent air flow reading for the MAF. I happened to have some experience recently with flow measurements in a small "wind tunnel". It doesn't take much to "deflect" air flow toward or away from a flow sensor.
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