Arctic-Rodz

Have an 08 550i and have already done the carbon filter delete, k&n drop in, and RPI scoop. Its done a good imporvement but I feel that the weakest link is that box around the intake tube and the accordion tube right after the mass air flow sensor.

This part.


The box around the intake tube is open to the main tube itself restricting the air flow and the little ridge part is doing the same.


Anyone know if there's a company who specifically makes that portion of the intake for the OEM air box?

I know everyone says that you loose performance with the afe intake but their system has the right design on their intake tube

pjinca

Dinan makes a dual intake for the V-8 cars, however, I would first contact John@Motorcepts (member here). He made his own dual intake for his 545 and might be able to provide you with some assistance (he's also a pretty cool guy)

Arctic-Rodz

Hope he chimes in on this thread

turboawd

what makes you think the airflow is restricted?

that box is an air intake silencer. i doubt it effects the airflow much.

Arctic-Rodz

How does it silence air? It just breaks up air flow.

ALL intake systems remove the ridged piece and that big extra box where the air swirls around in and finally enters the throttle body. They remove it for a reason.

turboawd

i think there is a little more science to it than just breaking up airflow....more to do with resonance and frequency.

Arctic-Rodz

Look at exhaust systems... why do perforated tube style systems(Magnaflow/Borla) work better than Baffle style systems (flowmaster) ?

Its about air flow. All OEM vehicles have that box, and to silence the cars they use big bulky baffle style mufflers and they use those big boxes before the throttle body to quiet it down. Everyone knows all it does is hurt performance. Why do they do it? Because not everyone wants to hear that "whoosh" on the intake and that growl off their exhaust.

But I do!!!

turboawd

work better how?.......flow? yes.........silencing exhaust? no
and free flowing exhaust is not always better. many cars need exhaust back pressure for torque.

Arctic-Rodz

The cats create quite a bit of back pressure as it is. Thats why the old school cars used the Flowmaster style mufflers because it created back pressure as well.

west

Turbo setup's aside, some of the older cars require back pressure as well to keep air/fuel ratio's within range (think of the old muscle cars). This is not the case with any of the recent naturally aspirated BMW's though... our fuel management is designed to be able to deliver the fuel when needed, within reason.

This guy does a half way decent job of explaining things:



The rest can be found here:

http://www.uucmotorwerks.com/html_pr...torquemyth.htm

Every now and then you'll see somebody blindly state that you should install smaller diameter piping when adding a dual exhaust to the 530i to make up for lost backpressure. Perhaps these people need to do some studying, or real world testing on a dyno.