[Diy_efi] RE

[R P Davis]

Dan, The 325iX is all-wheel drive so I do have some drivetrain loss.
With my 85 325e manual trans (before rust got the better of it) I was
getting 33mpg and I got rid of it with 204K miles.With my wifes 86
535i auto trans (before it had an accident that did too much damage) I
was getting 27 mpg on the highway and 22 mpg in the city. It took 4.5
gals of synthetic ATF to flush the torque converter. That was where I
saw the largest increase in fuel efficiency in that car. I also had a
2 stage Amsoil air filter in there. Amsoil doesn't have a 2 stage
filter fo the 325's. Mark D'sylva in Canada burns custom chips for
these cars, as well as a few others. I'm not sure what is possible
with the 2.5 liter engine. I know the 2.7 liter efficient engine for
the eta's (325e's) were pretty good. I didn't try hard with that
engine to get more mpg's as I was happy with that. I think if I had
fixed the trans leak and used Amsoil ATF in the manual trans,
installed a plasma booster, got rid of the "cold air intake" that came
on the car (BavAuto kit) and put the stock air box back in, and
installed some bigger spark plug wires I could have seen closer to 35+
mpg on the highway. I also gotta take it easy in my city driving as I
tend to wind the engine right up to 5K rpms between shifts. Even under
normal conditions I have a bit of a lead foot on acceleration. What
will a big bore thorottle body and a ported intake and maybe larger
valves & 3 angle valve job do for the efficiency of the car?

Have any of you looked at the kits from SUN auto in Japan for HYPER
grounding and HYPER voltage regulating? The grounding kits claim to
use 99.xx% pure copper and low impedance, as a result a better ground
and more HP, Tq, higher fuel economy etc, the voltage reg keeps a
constant voltage on the battery so when the alternator changes speed
with the engine or lights come on, etc the battery keeps a constant
voltage to all other devices, resulting in increased everything as
well. In theory I understand that it may help, but I'm not sure how
much it'll help. I have to clean up the grounds on this car and that
might help it out a little more as well. I've looked at dyno results
etc and they all post increases from these two devices. Hype/Myth?
Good idea? Great Product? Waste of money?

You lose quite a bit of fuel efficiency in the winter for another
reason. The air is more dense due to the frigid temps (like in VT,
I've seen days where -1 F was the high, and I've seen weeks where -20
F was the low every night, and I've seen -40 F a few times). I used to
think that fuel eco should go up in the winter b/c the air is colder
and more dense so you could get a larger charge in your intake, but
that counters out when the car is traveling thru the cold dense air.
Plus having your heater on and lights on (as there are fewer hours of
daylight) all put a load on the charging system which puts a load on
the engine.

~ryan
 -----
I'm surprised that you don't get a little better mileage with the 325.

I've got a 1998 528i with the 2.8L six.  On long highway trips I get 28-29
mpg and that's "leading the pack", not easy driving.  I get 25-26 with my
normal daily driving 22 miles each way to work, 50% hwy, 50% city.

I use 89 octane, $2 autolight spark plugs, completely stock car, BMW
synthetic engine oil.

I think these cars are pretty efficient already, don't really know how much
more you will be able to squeeze out.

What do you feel is possible?

I know tires are probably the biggest difference I have seen.  I loose a
good 2 mpg in the winter with my winter tires versus the summer tires.

Who burns chips for these cars?  Are you sure they will really get you
better mileage?  The factories really do a pretty good job of calibration.

I tune my 1994 Mustang GT electronically, full control with a TwEECer.  I'll
tell you fro experience there, its hard to beat the factory for overall
drivability.  I've heard a lot of complaints on discussion groups from
people that have bought chips from "experts".

Let us know what you come up with.

Dan Nicoson