While putting in an aFe panel filter in the airbox this morning, I noticed this waffle-like baffle in the turbo inlet hose right where the hose connects to the airbox. It is right at the mouth of the hose before you even get to the MAF.

What is this thing? My best guesses are either something to add turbulence to the intake air to help the MAF do its thing OR that is is a baffle to reduce noise. If the former, I'll leave it be. If the latter, I wonder if removing it might add some blow-off and intake sounds to the factory airbox.

 

to keep small birds and mice out of the turbo? lol

 

Oh it's gone, then! Birds add ~5 HP. (You lose a little low-end with mice, but gain ~8 HP up top.)

 

how deep is that baffle? can't tell from the photo

if it is thin, i can't see it doing anything to the airflow

if it is ~1/2" or more then it could be smoothing the airflow before the maf

just guessing

scott

 

My guess is 1/4 to 1/2 inch. I've seen a lot of talk on BMW forums about similar baffles and the consensus is that it is to reduce noise.

If some aftermarket intakes replace that hose, it might be safe to assume it is superfluous. I'm reluctant to assume, though

 

it could be all of the above.

* prevents large items from getting sucked into the turbo
* straightens out the airflow for better distribution (though before a turbo, why?)
* increass turbulence to reduce boundary effects of the tubing and improve flow

 

I'm not sure how that waffle would be necessary to keep large items out of the turbo. The object would have to go through the front grille of the car, through the snorkel, past the panel filter, then down the inlet pipe. It seems to me that the grille and panel filter would keep anything out of the turbo?

If it's there to prevent pieces of intake system from breaking off and going into the turbo, I'd think it would be the very last thing before the turbo, even after the MAF (since the MAF could theoretically break off and get sucked into the turbo).

My money says it either improves flow in some counterintuitive way (like dimples on golf *****) or is a measure intended to reduce noise (like the muffler on the hot side pipe to the intercooler).

 

I am interested in finding out about this as well. Of course I don't expect any power gain, but more interested in creating some noise.

 

Air straightener for the MAF. Makes the air less turbulent before the sensor. Other types of air straighteners like this would be something most have probably heard of before. Honeycomb. It is much more essential if you were to upgrade MAF housing to say 3" ID. When you start to get larger ID MAF housing your STFT and LTFT can get really skewed and start to pop codes on you for lean idle, etc.

Jason

 

It is an "air straightener" or it creates laminar air for the MAF. It is always a honeycomb construction that just smooths it out for accurate MAF readings.