Miata Mailing List: October 1998, Message #220

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After putting synthetic oil in Pan last night, ken and i decided to
fiddle around with the air filter box to get some more airflow to the
car.  Inspired by some hondas we have seen lately, this is what
we came up with:

1.  Remove the baffle that helps direct air to the intake nozzle in the lower half of the air filter box.  Remove the lower half of the air 
filter box.  Put both away, you no longer will need this unless you 
wish to revert to stock setup.

2.  Duct tape (in our case it was "ducK tape" :-)  the air filter element to the top half of the air filter box.  Be sure to form a tight seal all around the air filter.

3.  Loosen the hose clamp that sits just before the mass airflow 
sensor housing and then rotate the air filter top box almost
90 degrees so that the air filter is drawing air from the side away
from the exhaust manifold.  Tighten the hose clamp to keep 
the air filter in this orientation.

Now the air filter will flop around, b/c the lower half of the 
stock air filter box, in addition to restricting air flow, was also
providing support to the unit.  We compensated for this by
wrapping stiff wire around the new air filter unit and tying it to
3 convenient anchoring points (the unused metal 'loop' on the
side of the cam cover, the shock tower cap, the bracket to which
the lower half of the airbox attached).  This kept it from moving
around during cornering etc, or being pulled too close to the
exhaust manifold as the engine rotates under throttle.

Presto! More air to your car.  Minimized warm air to your car
-- for now, see below for next step!  A crazy crazy roaring sound
to the intake!  Crisper throttle response.  Most importantly -- 
a seat of the pants impression that there is more power being
produced in the midrange and high end.  The mid range
(around 3800 - 5000 rpm) especially seems to have benefited
from this mod.  

Next improvements?

1. Hook up dryer hose to provide a CAI effect to the air filter.
2. Replace the air filter element with a K&N freer flowing type.

I'll admit that it is a little unrefined sounding at around 4000 - 5000 rpm.  And the lovely exhaust note is no longer audible over the
intake sounds.  But if you like to experiment, like i do, then
this is a pretty easy mod to play with.  It will keep me busy
for a while until a proper air filter replacement comes out for the
99.  

Incidentally, in my car at least, there is enough room for a small cone filter on the INTAKE side of the engine.  This would allow 
much cooler air, being far away from the manifold, as well as 
eliminate the 2 bends and the length of the rubber intake tube
that goes around the engine from the intake to the airbox on
the exhaust side!  If no one comes up with something i am just
going to get an aluminum connector machined for the mass airflow 
sensor and OBD II sensors and rig the cone up on that side 
myself.  Coupled with the dryer hose (a la keith t.?  haven't seen
his setup yet), this should be the ideal setup for intake on the 99.

If anyone else wants to do this, let me know how it works out
for you.

And if anyone sees a problem with what i did, please let me
know before Pan gets hurt!!

Thanks everyone,
angelos
Pan the blue 99 who now sounds like a little monster and wants
to tell Chandy that when the GS-R growls at him now, he'll growl
right back!!  :-)