RE: Eta questions

[Thi VanAusdal <tvanausdal@xxxxxxxxxxxxx>]

John Futch said:
> I've got a few questions/myths about the E engine's I'd like 
> to get cleared up:
> 
> 1. I've heard that the "e"  engines had slightly larger 
> intake and exhaust manifolds
> to help  get better fuel economy, Is this true?
> 2. Isn't the only difference between an "e" and an "i" is the 
> head and the computer?

Actually, the 'e' intake manifold runners are *longer*.  I do believe
they are smaller.  Smaller runners = higher velocity (Bernoulli, baby!
who asked for his name yesterday?) at lower rpms.  The intake valves
and ports are smaller, circles versus rounded squares.  The idea is
that peak cylinder filling (and thus peak torque) occurs at lower rpms
to match the camshaft tuning.  Large ports affect low- and mid-range
torque because your gas velocity goes to pot.  That's why twincam motors
with variable runner length (a flapper valve cuts off one runner at low
revs, for instance) gain low-end.
 
> 3. What is the "super eta", and is it super on gas mileage or 
> on acceleration?
> 4. I have a 528e and was thinking of putting in a chip to 
> help with the throttle
> response, is it worth it? What will it do to my fuel economy, 
> right now I get about
> 25-28mpg city and 30-32mpg road?

The super eta used a 325i head casting with its bigger valves and ports,
and more aggressive chip and higher redline.  The higher redline gives a
higher peak HP number.  The pistons are different, too, to accomodate
the
bigger 'i' combustion chamber.  Drop an 'i' head on an 'e' and you'll
get
piss-poor compression (but you can rev to 6500!).  Wrong move.
I believe the Super Eta is super on both.  It's bridges the gap somewhat
between the 'e' and 'i', and is a good basis for a 2.7 liter 'i' motor
since you're just a cam change away.

With a chip, I believe your economy is improved for equivalent throttle
use.
If you are tromping it to the floor all the time, it will be low.  Duh.

I've heard reports that people get a mpg or two improvement with the
chip.
Your torque is up, so you need less throttle to move the vehicle, and
this is efficient.

 - thi v.

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