[Diy_efi] false myths

[Adam Wade]

--- gary <gas- at charter.net> wrote:

> Adam, I commend you on taking the time to go over
> (some of) the material JD wrote, as well as reading
> writings of the aerospace engineer, the driving
> force behind GAMI.

Sorry it took so long for me to get to it.  Writing
for four magazines is more labor-intensive than I'd
suspected.  :p

> From your perspective, sure sounds like you were
> wasting your time reading it.

No, I'm always interested in what people have to say,
especially if they say it in a new and different way. 
I think Mr. Deakin is a brilliant writer, has much
more technical knowledge than most people about
combustion issues, and he is introducing this stuff to
small plane pilots, who previously had no vehicle
delivering this info to them.  As I noted to Mr.
Deakin in a recent email, the particulars of the
physics hardly matter to a pilot, since the effects on
engine longevity, fuel consumption, and measurable
variables (CHT, EGT) are all bang-on.

> What was disliked by me, was the bits, like pieces 
> of a puzzle, that were scattered about in several
> articles.  Have no idea if this was by design.

He writes from the perspective of a pilot, one with
controls and gauges, but without underlying principles
to explain the relationships of those things when
used.  His articles are teaching pilots better ways to
think about operating engines; you are right that they
could be better organized if they were meant to
communicate the technical and physical bases of which
combustion science is built.

> Anyway, not sure of any other engineers with the
> combustion chamber test/logging (in real time)
> equipment and experience, that GAMI has, let alone
> willing to make available to the general public,
> other info, if indeed a question did surface 
> as to validity of GAMI's work.       

Well, I don't see where there is any question about
GAMI's work, but as Phil pointed out, you can get
technical details and research info ad nauseum from
the SAE, enough to keep you reading for the rest of
your life if you'd like.  ;)

>> ..... except for your failed analogy between a gas
>> stove burner and a combustion chamber regarding the
>> molecules being "too far apart" to produce
>> combustion....

> Didn't EVER state that in that together, in that
> context, Adam, so I won't have you waste your time
> looking for it in my posts.

Well, you said that you used Deakin as the basis of
your beliefs on the subject.  You said:

"AFAIC, misfire from too lean an A/F mixture, is a
false myth.  In reality, continual leaning can be
conducted until which time, the combustion flame, due
to a lack of heat, just goes out.  Sorta like turning
down the gas valve on a kitchen range, less and less
heat (not more) is generated until the flame, from a
lack of fuel finally goes out.  The misdiagnosed so
labeled 'misfire' is actually the result of the flame
in one or more cylinders going out ahead of the
others, due to the normal lack of a precise equal AFR
in all cylinders.  The physical appearance/feeling of
a misfire, is actually in reality, one or more
cylinders going dead, no different than if a plug
suddenly stopped firing." 
<http://www.diy-efi.org/pipermail/diy_efi/2005-March/000100.html>

Deakin made a single reference to a gas stove burner
in the articles you referenced, and in the same breath
said it was because the molecules of fuel were too far
apart to conduct the flame front propagation.  It
wasn't much of a stretch to think that your copying
the analogy from him meant you took the principles
from him, like you said you did.

>>> Start with the 'Back to the Future' series,

>> Read all three parts.  Nothing in there on
>> combustion chamber events or how they occur.

> What about the lean misfire?  Any reference to that?

Only that that is not the cause of rough running in
engines operated LOP.  Nothing about whether lean
misfire is real or not, or what it actually "is" if
not what other believe it to be.  Just that rough
running comes from the power differential between
cylinders that have different LOP mixtures.  I have no
quibble with that, but it doesn't support your claim
about lean misfire being a myth.

> It's a fair guess the author (professional pilot)
> was tutored (or had articles read) by the aerospace
> engineer noted above.

Everyone learns things from somewhere.

> If anything appeared grossly misleading or false, it
> would have been addressed.  So..... 

I hope you're not implying that aerospace engineers
never err when talking about combustion science.

Further, there was nothing in the Back to the Future
series that validated the point you made about there
being no such thing as lean misfire, so the article's
veracity is really not at issue here.

> As far as violating any gas laws are concerned, not
> sure of any of JD's wording or 'assumptions' as you
> imply, (that were not part of my original posts
> BTW), that he printed, that would be any less
> accurate than anything believed or trusted to be
> fact, up to the time his articles were written.

Um.  You're saying that no one on earth knew any
better that these specific cases might not
back-extrapolate to the general underlying principles
than JD?  After just saying that he was inexpert on
the subject at hand, and was probably coached?

And you were the one who proffered these articles as
being the factual basis for your claims.  Trying to
back away from his inaccuracies while still claiming
validity of your own points based on JD's supposed
expert status doesn't really wash very well.

> Yes, 'Perfect Gas laws' Nothin' like perfection.
> Even Einstein revised some of the indisputable laws
> he established.  However, that is NOT to state I
> personally do not acknowledge them.

Um.  Then why try to cast doubt on whether
temperature, pressure and volume are related, and are
the key principle underlying internal combustion?

> You are using some previous interpretation as a
> basis on which to 'grade' JD's work.

No, I'm showing where there are holes in his
explanation, since you called on them as the basis for
your beliefs, as well as pointing out where certain of
your beliefs cannot be extrapolated from his work.  I
don't know what "previous interpretation" you're
talking about.

> However, my original post IIRC, was in regards to
> lean misfire, stoich as being the high point of EGT,
> and acknowledging a given AFR that causes the
> quickest flame travel.

There's nothing in any of your referenced material
about lean misfire not existing.  I only see
references in the materials to the GPH reading that
corresponds with peak EGT, not stoich.  And the
quickest flame front travel would cause detonation at
nearly all engine speeds because it would raise both
the temperature and pressure of the end gas so rapidly
that detonation would be inevitable.  What is shot for
is a burn rate that is high enough to allow flame
front propagation at a reasonable rate, to prevent
partial burning or detonation; it's a delicate balance
between crank position (and the subsequent speed of
volume change in the combustion chamber), flame front
propagation, and cooling factors from in and around
the combustion chamber.  Deakin hints at this in many
different ways in those articles, but never says it
outright; however, he definitely does NOT say that
best power AFR gives fastest flame front propagation. 
It would not make sense to me that this would be the
case, and I haven't seen anything claiming that
(unless I missed something major in those articles).

> Those are the findings of engineers with
> actual 'real time' test data.  I'll respect their 
> findings, as accurate.

Well, produce some engineers who claim these things
and show some research data, then.  You have yet to do
so.

> If you prefer to kill the messenger, so be it.

*laughs*  Seriously, are you always this dodgy when it
comes to backing your own claims?  I'm not "killing
the messenger", I'm calling you out for claiming
things that ain't so, and then trying to use other
people's thoughts on the subject to justify those
claims, even when they never say what you claim. 
That's all.

> Anything in the way of questions you'd like
> addressed, straight from the source?

I email John directly, and can ask him if so inclined.
 But I don't think he has all that many answers about
combustion that I haven't seen/heard elsewhere.  The
ones he has, I've probably already asked him.  :)

> BTW, you referenced in one of your posts, the dialog
> you had with JD, regarding his articles.  Did he
> answer any of your concerns?   

Do you mean, did he respond to any of the points I
made in my last email?  Most of those points I hadn't
made, since it never occurred to me that someone might
extrapolate backwards to assume that at works inside a
combustion chamber would work anywhere.  Granted, he
uses analogies that may be somewhat misleading in that
regard, but until I saw it being done, it never
crossed my mind that someone might try.

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