[Diy_efi] fluid dynamics

[Adam Wade]

--- Bernd Felsche <bernie at innovative.iinet.net.au>
wrote:

>> During stratified charge operation, things are
>> intentionally done to RESTRICT the intake, to
>> increase flow speed and direct it for certain

> The "restriction" is not because of stratified
> charging,

Well, since that's all they use it for, and they turn
it off when theire' not in stratified mode, that
suggests otherwise.  ;)

> it's because of the part-load situation that allows
> stratified charge, and hence has lower flow
> velocities.

Flow velocity in the port is unimportant.  DIRECTING
the flow as it crosses th valve head is the reason
behind doing it, by the looks of it.

> The inlet is _less_ restricted under stratified
> charge (part-load) operation.

We were talking about the intake port, not the entire
intake tract start to finish.

> Do take some time to read that book on inlet design.
> :-)

Do take some time to read the post you're replying to.
 ;)

> Stratified charge has a leaner mixture away from the
> injector/plug.  The rich, ignitable mixture is near
> the plug.

Er, yeah.  I've been saying that since we started
talking about stratified charge.  :D

> That's an exaggeration.

Not according to most of what I have read, it's not.

> There is no such order of difference in the
> processor performance between Bosch ME and MED.

I wouldn't consider the ME to be a typical
currently-available production ECU, would you?

A typically available ECU is operating at 8 or 16 Mhz,
8- or 16-bit processing, typically, without any
ancillary processors.  Yes, there are exceptions.  The
ME is obviously one of them.

> Consider fuel costs (which will continue to
> increase) and emission regulations that will
> continue to reduce. It's much more difficult
> to do stratified charge with port injection than
> direct injection.

Agreed.  I think I pointed out that doing effective
stratified charge, to achieve the objectives reached
by GDI, is pretty much impossible with port injection.
 SOME of the advantages (at a rough gess, maybe 15-25%
overall) can be had by using GDI design concepts with
a modified current-generation port injection design,
but as I also pointed out, the cost/benefit ratio for
that will very soon fall below that of just using GDI.

> And stratified charge is the only proven, reliable
> means of capacity reduction to reduce carbon
> emissions in a naturally-aspirated engine.

Actually, according to Bosch, stratified charge is
very limited in that it forms a great deal of soot if
you try to exceed fairly low engine speed and load
parameters.  One of the reasons why the Bosch system
has 6 running modes; they have a best emissions mode,
a best power mode, and a best fuel economy mode, at a
rough description, plus two modes for accomodating
various emissions control systems, and an intermediate
mode for transitions.  They drive-by-wire ECU makes
constant decisions based on sensor inputs as to whcih
mode is appropriate at a given point in time.

> If you have an idea about how to do it better with
> port injection, run to the Patent office.

No offense, Bernd, but I'm starting to wonder if you
even read what I wrote.  I specifically stated that
port injection couldn't do what GDI can, in any manner.

=====
| Adam Wade                       1990 Kwak Zephyr 550 (Daphne) |
|   http://y42.photos.yahoo.com/bc/espresso_doppio/lst?.dir=/   |
| "It was like an emergency ward after a great catastrophe; it  |
|   didn't matter what race or class the victims belonged to.   |
|  They were all given the same miracle drug, which was coffee. |
|   The catastrophe in this case, of course, was that the sun   |
|     had come up again."                    -Kurt Vonnegut     |

__________________________________________________
Do you Yahoo!?
Yahoo! Web Hosting - establish your business online
http://webhosting.yahoo.com

_______________________________________________
Diy_efi mailing list
Diy_efi at diy-efi.org
http://www.diy-efi.org/mailman/listinfo/diy_efi