My M30 Air Box Swap (Tons of Pics)

[nando]

I don't think they are that stupid. Sillicone intake boots standout pretty easily.

[bmwman91]

Now I'm not all that familiar with the m42 but, why couldn't you use a aftermarket silicone intake boot that allows the maf to sit back a little farther thus allowing more room in the airbox?

Really awesome idea man, I bet that engine screams.

I wanted to keep as much of a stock look as possible. This is mainly personal preference, but I also want to be able to roll into a SMOG shop without having to turn a wrench first.

nice work - this would be a good idea for my M20 as well. I get a pretty big pressure drop in the stock M20 box, which is basically the same as the M42. I had a cone filter for a while but I just lacked the time and interest to build a proper shield for it, so I went back to stock. Plus it always got really dirty.



he wants to be able to pass smog. Sillicone intake boots scream aftermarket parts.

Dude yeah, I bet that even a stock M20 would benefit from this. It uses the same filter element as the M42, and the same size AFM. If you are going to do a big-six AFM swap, you might as well do a big-six air box swap along with it. Keep in mind that this box is from an E34, NOT an E28. You would probably still need to do some chopping to get the M30 AFM to fit since there is a long boot between the box and sensor in the original setup.

[nando]

I don't have an AFM, all I need is a place to mount an IAT. :p

[bmwman91]

I don't have an AFM, all I need is a place to mount an IAT. :p

Nice! You using MAP or Alpha-N? Megasquirt?

The M30 box's 90 degree elbow on the outlet might actually work out with the M20's boot, just make a little coupler from some pipe or something.
Part 14: http://www.realoem.com/bmw/showparts...67&hg=13&fg=15

[nando]

MAP

I think I could make something work... don't know why I never thought of this before!

[Balleristic31]

Very nice. Interested in the maf conversion when u finish it!

[jntar]

Nice work!

[tinkerputzer]

Looks great. I need to build one of these myself.

[iwantspeed]

Looks awesome nice work

[E30 Wagen]

Hmm, I'm going to look into this, thanks for sharing your work.

Also, that pulse intake chamber has always intrigued me, but I don't like MM's design, how they modified the manifold, so I'm having a hard time buying into it.

However I found this if anybody cares to read... http://www.freepatentsonline.com/4848281.pdf

[bmwman91]

Hmm, I'm going to look into this, thanks for sharing your work.

Also, that pulse intake chamber has always intrigued me, but I don't like MM's design, how they modified the manifold, so I'm having a hard time buying into it.

However I found this if anybody cares to read... http://www.freepatentsonline.com/4848281.pdf

Just curious, but what don't you like about how they modify the manifold?

Given how hot the cams in this thing are and its top-end power, I'd say that the PC intake does quite a bit because it is not gutless below 6000RPM haha (see: Honda S2000). I'd be happy to toss a stock manifold on and compare as well.

Really though, their setup seems like the only thing that you can really do without requiring customers to move all sorts of stuff around under the hood. The E30 does have a spacious engine bay, but the M42 has a lot of electrical stuff living right there. An idea that I always thought would be cool would be to have really long pulse chambers on there with an internal plunger that moved up & down with RPM so as to maximize intake reflections at all RPMs.

[E30 Wagen]

What I don't like about the design is that it doesn't look very thought-out, like it was the first idea they came up with that used materials they had laying around. An equal volume across all the PC doesn't seem guaranteed either. I'd really like to see some actual data comparing it to a stock manifold. My guess is that, with the pulse chambers, the HP and torque curves are weak at low rpm, which is a big turn off for me.

I think some sort of variable PC to optimize its volume across a broad rev range is the answer, but I get to wondering why no auto manufacturers use any type of PC at all.

[bmwman91]

Per MM, the PC setup is supposed to boost mid-range torque a lot with this engine, which would otherwise be sort of peaky feeling. I can attest that this engine pulls a lot more solidly in the 2500-4000RPM range than it used to. Some of that is obviously the larger displacement. Given the hot cams in there, it does pretty well on torque for being a smallish 4-banger.

I still want to make a variable PC setup with movable plungers in tubes that vary the effective area with RPM to keep it optimized. That would be BOSS. Either that or a variable runner length setup like BMW's DIVA system in some of their fancier engines.

[golde30]

cool build! never seen your car at any bay area meets, you should bring it out sometime!