Last update 12/9/2000
The full directions for duplicating the airbox and all the testing of it may be found here.
Step by step pictures of the above process.
I still build the airboxes the same as described in that article. I've lost count of how many people are running with them but I believe it to be on the order of 75-100 Z3s so far with probably a combined mileage of a couple hundred thousand miles pretty easily.
BTW, if you have a Fogged airbox please add it as a mod on your Z3 World Profile. Doing that should help me better keep a count on who has modded their airboxes.
I get a few questions on the routing of the hose from time to time. It does not need to be attached behind the foglight as it will stay in place on its own. But some people like to run a wire tie around the 4 inch hose and the power steering cables. This is no problem just don't crush the hose with the wire tie.
The above is a picture of how the hose is routed to behind the foglight. This occasionaly adds a little confusion to those performing the mod. Hopefully this will clear that up.
The above shows the factory sized inlet on the right and the Fogged airbox inlet on the left. That small factory inlet is the biggest restriction in the M44s intake path. It is not the airfilter that is the problem.
Another take on building the box.
The Fogged airbox can be done on '96+ 318tis but I've always done them in a slightly different fashion. The airbox in a Ti is pushed further back in the engine compartment. This leaves more room at the front so I add an additional inlet there and leave the factory setup alone.
Cutting the hole is a little easier on the airbox this way. Be sure
to add a hose running to between the radiator and headlight or down to
the foglight area. When you remove the airbox from the car do NOT just
pull off the factory intake hose. You will have a very hard time reattaching
it later. Instead just remove then intake snorkel from the box and leave
it attached to the hose. This way when you reinstall it in the car it will
be simple to reconnect. Be SURE when you cut the hole on the front
of the airbox it is below where the filter will reach down to when it is
reinstalled. Basically the first rib down from the top of the box is where
the filter goes to. Make the hole and inlet fit below that point.
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