Gene Kearns wrote:
On Wed, 28 Jul 2004 10:21:18 +1000, "K. Smith"
wrote:


Gene Kearns wrote:

On Mon, 26 Jul 2004 11:28:39 GMT, Short Wave Sportfishing
wrote:




Gee it seems if "ANY" of the others had a failure rate or 1 in 5 we
would have heard about it, the only others to come close were Opti &
surprise surprise they had the same 2 stroke lean mixture crap, as with
ficht the same hawked around for years & all the big engine makers just
laughed; as they should.

You mentioned that the last time and I've been looking around - I
can't seem to find this 1 in 5 failure rate documented anywhere. Can
you provide me a reference to this that I can look at? I know that
the failure rate for the midrange (100-150) engines was high, but 1 in
5? I'm not sure of that.



There was a high failure rate in some HP models. It was nearly a
bankrupting issue for the company and their customer service suffered
commensurately.



Net result is that if you have a person or computer making sure that
fuel-air mixtures are appropriate and that no detonation occurs, it is
a viable technology.


But that's it Gene they don't detonate when lean because there isn't
enough fuel there.


Isn't that the whole point?

No the "point" is that pockets of fuel remain unignited by the flame
front (end gases), long enough to be auto ignited as soon as the
temp/pressure combination goes above 250C, in most premises, planes cars
etc this would be detonation itself, in the early days we indeed
submitted that was the problem.

As I said the thing was few of them seemed to be failing while still in
lean mode, it appeared they were failing after the lean burn mode ended
& the engine spooled up.

The reason this was happening is because the mixture is so extremely
lean in the low rev range, much leaner than any car or aero engine has
ever tried, remember they need multiple continuous firing of the plug
just to get ignition!!! in a plane it would have gone rough at even
slightly lean & at the 40-1 mixtures claimed by OMC an aero engine would
stop outright. So they've sort of over ridden a natural safety by
continuous firing of the plug.

We say there just isn't enough fuel there to cause detonation damage in
lean mode, but the chamber temp continues to rise from a combination of
the lean mixtures slow flame front & the pressure spikes caused by the
auto ignition of the end gases.

When we talk chamber temp it probably means piston/rings only really
the rest is well cooled but again remember an aero engine has the piston
oil spray cooled & only see half the number of firings for a given revs
& even in turbo full takeoff mode has a much lower specific output
HP/ltr than the Fichts


You repeated claim to be a pilot so I'm surprised you're not well
across how this goes, as you lean the exhaust temp will actually drop
because there isn't much fuel there, however the piston will continue to
heat up,


That is a ridiculously false statement, unless there is detonation.
EGT is about the same at 50 deg lean and 50 deg rich. Cylinder head
temperature is much cooler at 50 deg lean than 50 rich..... read the
data, it is on the Textron Lycoming website.

The chamber temp or cyl head temp if you like will drop, but EGT is as
good an indicator however the same rationale applies.



as you richen & increase power there are rules which forbid you
to just go to full rich, you're supposed to do it incrementally so the
chamber's temp (piston/rings) can be brought back to normal temps before
there's full fuel there to support detonation.



You need to do a bit more reading. Moving a mixture from lean of peak
to rich of peak goes through a higher temperature regime at peak....
that is what peak is all about.

OK we agree on this, as you increase the mixture & power up the chamber
gets hotter from where is had been operating, no matter what & if it has
been operating at or near the max allowed then it will go over, in other
words save you very slowly richen the mix over time (minutes not
seconds) then the chamber temp "has" to rise as the power & mixture are
increased.

No rapid changes should be made from
lean to rich or vice versa.....

Again we agree on this?? to suddenly go from a lean running to full
rich as power is increased is not allowed?? Gee that's exactly what
Ficht & Opti try to do every time a usr powers up after a long run in
lean mode!!!.

but it has nothing to do with the
piston being hotter at a point when the engine is producing less
power....

We clearly disagree on this. I've read the references as you have I'll
put a few links in case anyone else would like to have a look & as
always a technical discussion would be great;

http://www.lycoming.textron.com/main...ngEngines.html

http://66.102.7.104/custom?q=cache:i...hl=en&ie=UTF-8

http://www.lycoming.textron.com/main...erLeaning.html

that isn't even logical and certainly doesn't follow the
laws of physics.

Always a good line, but if it's all that obvious you'll post the
reasons, remember all the time we are talking a chamber temp not going
above 400F which is very cool given the 2 strokes piston is completely
uncooled & see a firing on each & every stroke.





Assuming you really are a pilot as claimed then this is all common
knowledge to you yes???


If you doubt it, the verification is on the FAA's website.... it also
shows my Aircraft Mechanic's License and Inspection Authorization...
as asked before, where are your credentials?



Now compare how Ficht do it, they run so lean it won't even ignite they
keep firing the plug, them once the chamber is good & hot they suddenly
over seconds give it full mixture & a big increase in power??? What's
surprising is that as many survive as they do.



The fact that they *do* work, are commercially available and in use
today, have a loyal following, and do sell.... should be an ample
indicator to a reasonable person that they are wrong about seeing
perpetually faulty technology.... why, again, don't you get it?

They don't ALL fail just as not all pilots who over lean die, but
enough in both categories fail to make it not a commercial thing.

At least with the aero engines there's an element of self inflicted
result, with ficht the owner has no input, he's either lucky or not.


PS.

Do a google on "lean burn engines" and you will find that there are
dozens of companies manufacturing engines and/or controls for engines
to maximize the use of "lean burn." Time to throw away that old
engine text and enter the 21st century.


Read the articles closely Gene they are using lean at idle, overrun &
light throttle high speed cruise, never ever at power, the only ones we
can find are our discussions subjects.

A big OB on a heavy boat, propped to achieve a high top speed, will be
making significant HP (in HP/ltr terms) to plough the boat along nose
high in say a no wake zone & doing this in the upper end of the Ficht's
lean burn mode. With a totally uncooled piston then subjected to a
sudden power up & full rich mixture??? Unless I've misunderstood you
above this "must" result in an increase in chamber temp??? it's a
lottery with very good odds if you want to go gambling, 4 out of 5 are
winners but damn, the tickets are very expensive.

I've never said this is easy nor obvious Gene, gee if it was we
wouldn't have spent months & thousands of words in the early ficht days
trying to warn people:-) everybody would be doing it:-) we tend to
specialise in the difficult:-) but it's true & yes you will have to
stop, read & then think but at the end you'll see that 7000 chucked
unemployed, 1.3 bil of pensioners money, nobody has admitted how much
Bomb lost but it would be heaps & endless hurt boaters always trumps a
few brand loyal lucky users who are in the main dealer groupies or lying
dealers.

K