325e mods...airbox, etc...what has worked for me (long)

["HOTROD930" <HOTROD930@xxxxxxxxxxxxx>]

Adam wrote:
"Has anyone had any experience with these high flow air intakes.  I'm
thinking of buying the BMP one for my 86' 325e, and then boxing and
insulating it from the rest of the engine compartment.  I'm also wondering
how well these older BMW engines take performance mods.  I have 150K on this
one and it was used so I don't know jow the last owner abused her.  I'm
afraid that if this really works the extra hp may caude me throw a rod or
kill my bearings. At 150K the engine could be well worn despite how well it
runs."
*******I've done a bunch of work to my 1986 325 (eta motor), and I thought
I'd share what has worked for me as far as "worthwhile" mods;
I'm 36 years old, and not out to impress anyone with noisy exhaust or M
badges or aftermarket "body kits", I like stuff that is oem in reliability
and appearance, but I do like to improve handling, braking, power, etc.

Instead of running a cone filter, I have a K&N replacement filter, and I
made some good sized openings on the lower part (before the filter) of my
airbox, then modified the panel behind my headlight to allow more cold air
to enter that area.  I only modified the side of the airbox away from the
engine, and this is very "low key", which doesn't raise eyebrows at the
bi-annual smog inspection, but allows more air with a throaty growl.  I
didn't want to alter the broad torque band of my car, just to improve
breathing a bit.  I also installed an oem exhaust system from a 325i, which
was a bolt on, and has two pipes all the way from front to back.  Not really
noisy, but it does have a nice "note" to it.  Again, very low key, but nice
improvement in breathing.

The 3.25LSD differential from a 535i of the same era is a great upgrade, and
really makes these cars peppy, as well as the Jim C. chip.  I'd tried the
Dinan before, and it was fine, but I hear great things about Jim C. and have
it now.  I don't know if I could tell the difference, they both are a vast
improvement over the stock chip.  I tried Jacobs ignition, but that didn't
do anything, so I put in a new Bosch coil and oem wires, and that's plenty
of spark, I think.  Recently, my "low" front spoiler (car lowered with
Eibach's, has factory "is" spoilers front/rear) kicked up some debris that
put a hole in my transmission.  I figured now was the time to check out a
lightened flywheel.  Metric Mechanic set me up with a 13 pound oem lightened
flywheel (aluminum ones I understand are considerably lighter and really
degrade the driveability among other things), which replaced my stock 23
pound flywheel.  Man, what a difference!  It's still very smooth, but now it
spins more easily and accelerates noticeably better.  This made sense since
I was having my clutch checked for wear anyway, but before this I didn't
want to drop the exhaust, trans, etc., just to change the flywheel.  The
flywheel was $250, and I think well worth it, virtually no additional labor
costs.

Overall, the eta motor is nothing dramatic when you wind the motor out, but
it has a wonderful, wide, smooth, torque band that I find makes it an
absolute blast to drive through town.  On the freeway with just 15" wheels
(oem looking BBS basketweaves) and V rated tires, I feel like I'm driving a
race car on a track at very low speeds.  I accelerate for sweeping turns
rather than slow down.  I took the car out to Thunderhill Raceway for a
Tracquest event (www.trackquest.com), and the car held up very nicely,
although I wished it had about 50 more HP. ;)  Nevertheless, at 215k miles,
I don't feel tempted to do the "i head" conversion any time soon, as I'm
enjoying the wonderful torquey eta motor and all of its "enhanced"
strengths.  I drive this thing HARD and it comes back for more, it's a very
durable engine.

My $.02

- -Rod Birch