M42 and M20 airbox interchangeable?

[kkamakasi]

Can I fit an M20 airbox onto an M42 engine?
Specifically the top part of the airbox which connects to the bottom part and also connects to the MAF (part circled in red below)

[Dj Buttchug]

no im pretty sure it wont work. ive tried it

[AndrewBird]

Comparing them here:

http://www.realoem.com/bmw/showparts...35&hg=13&fg=20

http://www.realoem.com/bmw/showparts...34&hg=13&fg=20

I would say no, an M42 top won't fit on an M20 bottom, or visa versa. The AFM gasket is the same part number though, so you might be able to swap out the entire air box, putting the M42 AFM on the M20 box.

Why would you want to do this anyway?

[Dj Buttchug]

^ you can do that but the mounting position of the m20 box is different from the m42. Also the angle at which the AFM is on each air box is different. I tried to do this when I swapped an m42 into an m20 car. It doesnt work no matter how you interchange parts

[wazzu70]

^ you can do that but the mounting position of the m20 box is different from the m42. Also the angle at which the AFM is on each air box is different. I tried to do this when I swapped an m42 into an m20 car. It doesnt work no matter how you interchange parts

Truth. I swapped my M42 into an M20 car and tried the M20 airbox. Later switched to an M42 airbox and it didn't line up with the mounting bracket on the fender.

The M20 box is longer along with some other differences (M42 has mounting bosses on the top piece, M20 on the bottom, ect.)

[bmwman91]

No, and you would not want to. The M42 uses a filter of the same surface area as the M20, so there is no performance gain potential. They are not interchangeable anyway.