By Sean Steinman
Seems everyone wants to put a K&N cone type air filter on their E12, but the price is a bit much for a "kit". I've come up with a solution that doesn't cost quite as much. Total around $90, and a little "elbow grease".
First thing I needed was a suitable sized K&N cone. I came up with one at a local aftermarket parts dealer for $50. K&N Part #F030A6 (also had #B020c4 on the inside of the cone).
The next hurtle was to get the pipe sizes from the original elbow on the air flow sensor, 2.5", to the 3" I.D. of the K&N. I looked at a few muffler shops/parts stores and all they came up with was an over priced stretched piece of muffler pipe. Looked pretty bad. I finally found the pipe I wanted/needed at a shop where they do custom exhausts. They had a cabinet full of muffler pipe ends. I saw one that looked to have the right O.D. sizes on both ends
and it was stainless to boot… $30… I did have to cut off the angled end, but I came up with a nice piece of pipe for the intake. Don't forget to clean up the pipe if you cut it, you don't want the fragments being sucked into the FI system and ultimately into your motor!
The next thing I needed to deal with was the idea of some type of heat shield. When you remove the stock air cleaner assembly, the manifold is directly under where you would put the K&N setup. Don't want to be sucking in that HOT air!!! Also when you remove the stock air cleaner, the air flow sensor is no longer bolted to anything, and will move around a great deal if not fastened to something.
I went off to the local "U Pull It" and found the lower half of a stock air cleaner, 5 bucks! I then cut the sides off with tin snips and now had a dual purpose part - a heat shield, and a mount for the air flow sensor.
I did cut a bit too much on the one that is in the car right now but will fix that soon... needs more support... Turns out I ran into a "snag". The K&N was hitting the heatshield ...just a small amount, but enough to not be able to point the assembly downward (to clear the hood). I had to take it out and trim the rubber elbow approx. 1/4".
Now it fit in nicely. It is a bit close to the heatshield, but doesn't rub or hit.
All in all, I chased parts longer than it took to assemble this. It seems to make the car a bit better on the bottom end, but it also somewhat noisier. It LOOKS COOL too!!!
Sean, aka Kaveman