Re: E28 Questions

[rusmaster <rusmaster@xxxxxxxxxxxxx>]

Larry and Brian writes,

snip

> >4) What can I expect for MPG for this car.  I'm getting about 22 on
> >   the road now.  This seems low, but then again I'm used to my 325,
> >   which, unfortunately for me, is for sale.
> 
> Normal.  You may get a response from another Digester who compiled a
> ton of replies.  I get 19 mpg around town (but I like corners  ';~)
> and 24-26 freeway only.  By the bye, my OBC and simple arithmetic
> agree to +/- 1 mpg almost all of the time.

I agree here.  The OBC is extremely accruate in the calcs I've made with my
'88 535iS.  I have lots of bolt on stuff and I get only about 16mpg all
around.  I do lots of commuting and highway driving, so it's fairly mixed. 
Before all the mods I used to get ~19mpg.


> >Other than that, the car's great.  I can't wait to make some mods
> >this winter.  What do you recommend?  I was thinking of a K&N (maybe
> >cone) filter and a JimC Chip.
> 
> JimC chip is the best single performance mod - whatta guy!  Best next
> is a short shift kit (I'll bet yours is sloppy).  Next would be sway
> bars, presuming you have ditched the TRX's and have real wheels and tires.
> Don't bother with the cone.  Megabytes written on the topic, even a few
> facts.

The K&N stuff on these cars makes no difference.  In the dyno tests I've done
on a 248C, I ran the stock intake with no air filter, the gain with no filter
was 5 ft/lbs and 1hp.  Whoppee!  Remember, the E28 intake is a factory cold
air intake.  And at full intake volume, the stock system is oversized for the
displacement.  My opinion is, of all the '80s BMWs, the E28 might have had the
best intake of them all.  If it only had a MAF instead of a AFM, it would have
been the best.

On the chip, I'm not convinced these really do much.  It MAY help in part
throttle responce and MIGHT improve idle somewhat, but the M30 engine is so
torque heavy, the increases the chip gives in performance are almost
un-measurable in any acceleration test myself or anyone else has done.  The
tunners do get more hp and torque from these chips, but they don't improve top
end performance.  And unless your car is runnign like new, the other factors
of age and wear&tear eat up all the gains you get from a chip.  In defense,
putting in chip and doing the dyno work did point out all the problems in the
car from wear&tear and aided in the daignosis and subsequent repair.  Plus the
chip forces you to use high octane, I do miss using the regular grades in
longer non high-perf. driving.  The stock E28 runs great on regular.

Take Care,
Russ

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