Diamond

Well keep in mind-
1.I removed the big foam sound protector from under my hood--
2.I have a BMS (like K and N) filter which by itself is louder

3. I made the box signifigantly smaller in volume by taping straight over every crevice..

and even after all this the sound is not night and day-it is a subtle intake sound that my ears pick up because I have had the afe, stock and diefferent filters in between.

At first it was for sound but now I think this mod is purely worth it for the boost in performance.

Also you have a different engine under your hood-for one it is not valvetronic, uses the throttle body, has a two stage variable runner intake manifold instead of the 3 stage that the n52 has (you have the m54 engine)..

The performance of this mod is largely dependent on the improved velocity and probably resonance of the air flow--I am guessing this will largely vary between two drastically different engines. The n52 has no active throttle body-its always open with air controlled into valvles by the valve lift itself. This alone pressurizes the system in a much different manner. The pumping losses they talk about is the drop in pressure needed in the valvles for air to flow from the intake manifold to the engine--with a throttle body that opens and closes, the flow starts/stops quite a bit which means it takes more of a vaccum to reduce pressure enough so air flows to the valves. The n52 with open throttle body means the air is in constant flow to the valves and a simply opening of the valve and the air is right there to go in, rather than needing to come from the throttle body--that is an easy way to look at.

Anyway I can only speak for the n52 engine in the 530.. i hope it is as effective for you-

The other thing I gave mine 50 miles of driving before measuring anything-your computer needs to adapt to the change in air habits.

Plus I have the bms tune for my engine that changes a/f ratio to very rich and advances timing--

I am guessing the tune is key to this as the rich mixture has sufficient fuel to utlize some extra air--whereas stock has it quite lean that any additional flow of air has no extra fuel to burn with--just my theory.

So anyway anyone with an n52 should definetly try this

Diamond

In this picture you see the part in the bottom right hof the picture-the very bottom right of the airbox bottom-it is that slope you want to completely get rid of by adjoining tape from the wall to the other wall on the other side of the dip-so you basically put a "bridge" over this-that is the big thing for the bottom.

The big thing for the top is the wall that the outlet hole is on (on the far right) there is a stepped cavity on that whole wall-again bridging over this so the new "wall" is flush with the outlet hole.

Also every piece of tape near the inlet or outlet holes-I feathered my edges to have very smooth longer bends and the tape went onto the edge of the holes so it had no "ridge" created between the edge of the hole and the tape.

Smooth bends and flat surfaces and less volume -I am going to try to signifigantly reduce more volume with the thicker tape--trial and error

NguyenAzn

wow man u sure type alot. but nice mod. But some pics would be great !

Diamond

Ya that is from years of instant messaging 5 people at once and typing 120 words per minute--however accuacy and punctuation suffers clearly!

Gene

both rizbel and brabus209wamg also touched basis on this idea when they were posting about their DIY Dinan dual intake..

https://5series.net/forums/topic/828..._1#entry967150


concept makes sense tho....either cut the waffle patters out or cover them with the tape.....it would seem to make the air less turbulent and allow more air flow....

in the link above rizbel only left the vertical separators which lead straight to the intake hold at the end of the box...

Diamond

However this method is signifigantly better and improved in my opinion. One of the main reasons I believe my way works is because you are decreasing the volume of the air box.

Think of it analogous to adding an aftermarket exhaust-if you go with piping that is too much larger than stock you can get a loss of flow velocity and scavengin of gases (this applies to NA motors only of course)-that is why RPI actually uses less diamter than stock to have an increase flow and scavenging effect..

So back to the airbox if you decrease its volume AND you make the path more direct from in to out which is done by taping variosu sections completely off and funneling it all to one central place--not only does the velocity increase from a smaller volume. Velocity of gases flow faster with less volume--and this air is flowing not only faster but faster in a more direct path-that is getting the same effect as an Hemotlz resonator effect--a "mini" charge of air rammed into the intake. If one had the know how which I could figure out if I tried I am sure but you could tune your airbox further to find out exactly which specs you need to have the boost at a chosen rpm-so if you wanted a kick in the 6k rpm range you could tune for that by changing volume and shape of box-this is beyond my skills but in effect it acts this way.

The faster the air, the faster the cylinder can fill--

I hope some peeps try this, I can really say the car feels a big jump in perforamnce and I am skeptical of butt dynos but this has no roaring sound to make you sound like your going fast or tricking you into thinking that. And really if in 4 years I never achieved 36 mpg and after this mod I did-that is not a fluke--it was also replicated tonight at 35mpg..

That is pretty darn good for a gasoline engine that has good power 35mpg is nearing the diesels--not quite but maybe 10mpg away or so?

Diamond

Ok guys here is pictures snagged from the other link on some other folks who modified there box

On both of them I put a solid color line on the new borders I made in the box-I did this by taping off the sections as the lines display-Also the solid red lines in the bottom piece show that large dip dead in front of the intake hole (keep in mind this guy drilled a second hole--that doesnt exist on mine or stock box--The red lines on this dip I built up and covered so it is absolutely flat-the entire bottom piece is all flat, with no dips.
I spray painted the picture to show where the tape is--it is covered everywhere but the spray just is a landmark its not literally in that configuration! What was harder to show but I tried with lines is that from the outer edges, the tape is tapered in softly--all filtering to the inlet and outlet.

However I tried to keep all area exposed to the filter unblocked as I did not want air to be obstructed. So I basically blocked off all the edges and just left the space where the air enters teh filter.

In the Top piece picture I spray painted white the area to show that is a big ledge that needs to be built up so it is absolutely level/even with the outlow hole. I also put a solid line showing the border I created that is about 1/2 inch inward from the old border. I also obviously covered all the waffle and again funneled everything towards the outlet hole with feathered soft edges--kind of like a big funnel all draining into the outlet hole.

When you do this there basically should be no difference at any point in the top or bottom in the level of the floor or roof of the box, no more dips, turns, crevices-All absolutely flat, also no right angles--all feathered smooth bends around the cornder with a slight funnel toward the holes..

Too bad RPI did not capitlize on this-they could have done much more testing and created a plastic mold that you could basically place into the top and bottom pieces and they could have sold it with the scoop as a true intake modification. I wish I had the tools or know how-what an easy mod that you could sell for 150 bucks a pop--a totally irriversible intake mod with simply popping in two pieces-one into the bottom and one in the top that would do what the tape is doing-flatten and contour the box---if anyone has the know how I bet you could market this to the e60 flks

mannynj

Hmnn...that mold could totally be done with fiberglass. Use putty(or playdoh) to shape it how/where you want, and start laying fibers/pouring glass. Then you can spray the finished product with a few rounds of Cascade VBS1 Quiet Kote deadning to eliminate any vibration.

cleung

I was thinking the same thing, someone could definitely do a mold with fiberglass.

AKAlius

Good stuff.