Scientific Data on Engine Operations

[O. Sami Saydjari]

This is actually a split off from the "Rotating Injectors Among
Cylinders" thread. I prefer not to distract that thread any.

I must say that I find the evidence presented in support on LOP to be
uncompelling. Although it is certainly appealing at the gut level, it
is a far cry from scientific evidence that LOP operations is better for
the engine and will lead to longer TBOs.

I am not saying that the assertion is false; I am saying that I have yet
to see properly controlled long-term experiments that prove the
hypothesis that is so emphatically stated as truth.

I hasten to add that it does not appear that the engine manufacturers
have done any scientific experiments to suggest that ROP operations lead
to longer TBOs or better operation. This is what I find so frustrating.
So much depends on quality information about proper engine
operations, yet there appears to be little science behind the assertions.

OK, I said my piece. I am done venting now.

-Sami
N2057M, Piper Turbo Arrow III

[Denny]

Sami:
GAMI is producing certified STC / PMA injectors for a number of
years... They have a large amount of engineering data from test
engines, and a huge base of customer recorded engine operating data out
in the field... This constitutes a database of real world engine data,
more than the manufacturers ever dreamed of recording and magnitudes
more than the manufacturers use to have an entire engine certified...
To certify an engine the manufacturer runs it on a test stand for ~200
hours, tears it down for wear measurements, and that is it; It's
certified...
A case in point is the ongoing Lycoming crankshaft saga... The customer
is LYCOMING's engine test stand... GAMI has recorded more test stand
and flight hours just developing their injectors than Lycoming has for
rest of the entire engine itself...

If GAMI injectors and LOP operation was lunching engines we would know
it by now ... If you don't like LOP operations then don't do them
and save your angst for something that is a real problem... Simple, eh
wot...

cheers ... denny

[Doug]

I have often thought that what is needed is a scientific study of what
works best in aircraft engines. Get a statistically signifigant number
of engines. Rebuild them. Put monitoring equipment in the aircraft.
Instruct each owner of the aircraft to run the engine in specific ways.
Numerous groups of engines being run different ways. Oil selection, oil
change frequency, leaness, shock cooling etc could all be studied.
After 2000 hours of running one would have a pretty good idea of cause
and effect.

[Paul kgyy]

I agree with Denny - George Braly has been using sensors that actually
record internal cylinder pressures in real time. I believe they do
know what they are talking about. I just went to Lycoming's web site
to do some reading on this yesterday, and their publications appear to
have no basis other than company CYA.

[Michael]

> So much depends on quality information about proper engine
> operations, yet there appears to be little science behind the assertions.

You are quite correct - there is very little science here. There is
certainly a lack of solid statistical evidence. In this situation, you
pretty much have to work from engineering first principles.

Let's start from what is scientifically defensible:

Operating 50 degrees LOP vs 50 degrees ROP (which is what many
manufacturers recommend) means that:
The engine runs slightly rougher. Extra vibration.
The peak pressures in the cylinder (and thus transmitted to the
crankshaft) are lower. Less stress on crankshaft, bearings, etc.

That's about it. Everything else is rumor, conjecture, and guesswork.

The slightly rougher running may in the end reduce the life of the
engine more - or less - than the higher peak pressures in the
cylinders.

Oops, I guess we're done until an actual controlled study shows us
which factor is more important.

Michael

[Paul kgyy]

The extra vibration occurs only if you don't have proper fuel
distribution LOP. Admittedly, this is normal for carburetion and
common for fuel injection, but that's the point of using GAMI injectors.

[O. Sami Saydjari]

Yes, exactly. -Sami

Doug wrote:

> I have often thought that what is needed is a scientific study of what
> works best in aircraft engines. Get a statistically signifigant number
> of engines. Rebuild them. Put monitoring equipment in the aircraft.
> Instruct each owner of the aircraft to run the engine in specific ways.
> Numerous groups of engines being run different ways. Oil selection, oil
> change frequency, leaness, shock cooling etc could all be studied.
> After 2000 hours of running one would have a pretty good idea of cause
> and effect.
>

[O. Sami Saydjari]

Denny,

Just to be clear here, I have no angst at all, only uncertainty. The
GAMI data is admirable and is a good start...but it is only suggestive.
As others have pointed out, the connection between some of what GAMi
measures and the impact on TBOs for example, is really speculation at
this point. It does not need to be. Some scientific controlled
experiments could do wonders here. That is my only point. Hats off to
the GAMI folks for starting us down the right road. -Sami

Denny wrote:

> Sami:
> GAMI is producing certified STC / PMA injectors for a number of
> years... They have a large amount of engineering data from test
> engines, and a huge base of customer recorded engine operating data out
> in the field... This constitutes a database of real world engine data,
> more than the manufacturers ever dreamed of recording and magnitudes
> more than the manufacturers use to have an entire engine certified...
> To certify an engine the manufacturer runs it on a test stand for ~200
> hours, tears it down for wear measurements, and that is it; It's
> certified...
> A case in point is the ongoing Lycoming crankshaft saga... The customer
> is LYCOMING's engine test stand... GAMI has recorded more test stand
> and flight hours just developing their injectors than Lycoming has for
> rest of the entire engine itself...
>
> If GAMI injectors and LOP operation was lunching engines we would know
> it by now ... If you don't like LOP operations then don't do them
> and save your angst for something that is a real problem... Simple, eh
> wot...
>
> cheers ... denny
>

[Frank Stutzman]

O. Sami Saydjari > wrote:
> Denny,

> As others have pointed out, the connection between some of what GAMi
> measures and the impact on TBOs for example, is really speculation at
> this point. It does not need to be. Some scientific controlled
> experiments could do wonders here. That is my only point. Hats off to
> the GAMI folks for starting us down the right road. -Sami

Several of the GAMI principals hang out on the Bonanza owners list. While
I guess there hasn't been a double blind (if you could do such a thing)
scientific test, the evidence is pretty much out there.

You've got to remember that LOP operations are nothing new. When the
radial engine was king, airlines ran their DC-4, DC-6 and Constellations
LOP as a regular practice. Engines almost always made TBO.

Now I guess you could say that the engines in our little planes aren't the
same as the large radials. Could be, I'm no engine expert. The GAMI
folks, though, will tell you that it doesn't matter wether your running a
lawn mower or a double-wasp radial, the combustion event is the same.

--
Frank Stutzman
Bonanza N494B "Hula Girl"
Hood River, OR

[Michael]

> The extra vibration occurs only if you don't have proper fuel
> distribution LOP

I have never seen an engine, GAMI equipped or otherwise, that was as
smooth LOP as it was ROP - and I've seen a lot of them. That's not to
say that I haven't seen a lot that were acceptably smooth - I have.
That's also not to say that I haven't seen engines that ran smoother
LOP with GAMI's than ROP without - I have. But those engines with
GAMI's ran even smoother ROP. When operating LOP, the fuel-air
distribution needs to be much closer to perfect than ROP for the same
level of vibration, simply because the power vs fuel curve is MUCH
steeper. By the same token, unless the distribution is absolutely
perfect (which it never is except maybe at one altitude and power
setting) ROP will always be smoother. I'm sure that at some point the
difference isn't important anymore (the vibration due to power
imbalance is swamped by other factors) but nobody can say with any
authority what that point is.

Of course all the piston airliners routinely ran LOP - but it's
important to remember that over the course of its life, the cost of
fuel the engine burns is significantly higher than the cost of the
overhaul - and thus LOP operation, which can easily save 10-15% for the
same power and speed, can be economically advantageous even if it does
measurably shorten engine life.

Michael

[Matt Barrow]

"Michael" > wrote in message
oups.com...
> > The extra vibration occurs only if you don't have proper fuel
> > distribution LOP
>
> I have never seen an engine, GAMI equipped or otherwise, that was as
> smooth LOP as it was ROP - and I've seen a lot of them.

I'll give you a ride in mine.

Not only as smooth, but temps, pressures, carbon deposits, etc. are all MUCH
better.


--
Matt
---------------------
Matthew W. Barrow
Site-Fill Homes, LLC.
Montrose, CO

[bill hunter]

You have to consider the smaller operating range when running LOP. Small
changes in altitude, temperature, or pressure will wider fluctuations in
temperature when running LOP as opposed to ROP. We would all like to think
we keep the engine perfectly leaned, but over the 2000 hours on a typical
engine, how many times does the average pilot let the temperature drift a
little before catching it. How long at 25 or 15 LOP before you shorten the
engine life.
I change altitudes a lot, and tend to fly high when weather permits. I also
have a turbo arrow with a very sensitive throttle that needs to be adjusted
continuously during climbs and decent. I don't need the aggravation of
having to adjust the mixture 3 times as much because I was LOP. I know
during the 2000 hours I would eventually get distracted in busy airspace,
and end up running too close to peek during a cruise climb.

"Michael" > wrote in message
oups.com...
>> So much depends on quality information about proper engine
>> operations, yet there appears to be little science behind the assertions.
>
> You are quite correct - there is very little science here. There is
> certainly a lack of solid statistical evidence. In this situation, you
> pretty much have to work from engineering first principles.
>
> Let's start from what is scientifically defensible:
>
> Operating 50 degrees LOP vs 50 degrees ROP (which is what many
> manufacturers recommend) means that:
> The engine runs slightly rougher. Extra vibration.
> The peak pressures in the cylinder (and thus transmitted to the
> crankshaft) are lower. Less stress on crankshaft, bearings, etc.
>
> That's about it. Everything else is rumor, conjecture, and guesswork.
>
> The slightly rougher running may in the end reduce the life of the
> engine more - or less - than the higher peak pressures in the
> cylinders.
>
> Oops, I guess we're done until an actual controlled study shows us
> which factor is more important.
>
> Michael
>

[Matt Barrow]

"O. Sami Saydjari" > wrote in message
...
> Yes, exactly. -Sami
>
> Doug wrote:
>
> > I have often thought that what is needed is a scientific study of what
> > works best in aircraft engines. Get a statistically signifigant number
> > of engines. Rebuild them. Put monitoring equipment in the aircraft.
> > Instruct each owner of the aircraft to run the engine in specific ways.
> > Numerous groups of engines being run different ways. Oil selection, oil
> > change frequency, leaness, shock cooling etc could all be studied.
> > After 2000 hours of running one would have a pretty good idea of cause
> > and effect.

Between the known physics of combustion, the test stand that GAMI has been
operating for several years, the engineering data the P&W and the airlines
generated for a couple decades of operating the radials...I don't think
these folks really want scientific data.

[Matt Barrow]

"bill hunter" > wrote in message
...
> You have to consider the smaller operating range when running LOP. Small
> changes in altitude, temperature, or pressure will wider fluctuations in
> temperature when running LOP as opposed to ROP. We would all like to think
> we keep the engine perfectly leaned, but over the 2000 hours on a typical
> engine, how many times does the average pilot let the temperature drift a
> little before catching it. How long at 25 or 15 LOP before you shorten the
> engine life.

Well, I hope you've kept adequate re$erve$ for a top overhaul in addition to
your early MOH.

[Matt Barrow]

"O. Sami Saydjari" > wrote in message
...
> This is actually a split off from the "Rotating Injectors Among
> Cylinders" thread. I prefer not to distract that thread any.
>
> I must say that I find the evidence presented in support on LOP to be
> uncompelling.


The exiting data is not only compelling, it's pretty much overwhelming.

> Although it is certainly appealing at the gut level, it
> is a far cry from scientific evidence that LOP operations is better for
> the engine and will lead to longer TBOs.

You need to learn to integrate information.

But why would anyone want to kick in a load of $$$ when Old Wives Tales are
so "compelling". Not only is there no known data to support these OWT's, by
the time people finally quit sitting on their brains and assimilate the new
learning, we'll probably be using mico-nuclear engines.

From geocentric, flat earth, and a host of other "knowledge bases", I guess
ROP/LOP is just another notch in human nature.

I suspect what's wanted here is not scientifc data, but excuses.


--
Matt
---------------------
Matthew W. Barrow
Site-Fill Homes, LLC.
Montrose, CO

[Matt Barrow]

"Paul kgyy" > wrote in message
oups.com...
> The extra vibration occurs only if you don't have proper fuel
> distribution LOP. Admittedly, this is normal for carburetion and
> common for fuel injection, but that's the point of using GAMI injectors.


http://www.avweb.com/news/reviews/182558-1.html
-----------------------


These subjective reports were confirmed recently when Chadwick-Helmuth spent
several days running tests on a 1993 Beech F33A instrumented with one of
C-H's latest state-of-the-art vibration analyzers hooked to multiple
accelerometers and vibration transducers. Tests were flown at a wide range
of power settings and mixtures using a set of standard TCM nozzles, then
repeated after GAMIjectors were installed. The results indicated that the
GAMIjectors reduced vibration levels at the 2nd order frequency and at the
low 1/3rd order frequency by 60% to 80%.
================================================== ================

[Michael]

> The exiting data is not only compelling, it's pretty much overwhelming.

I'm glad you feel that way. Those of us who are actually qualified
practicing engineers do not concur.

Michael

[Matt Barrow]

"Michael" > wrote in message
ups.com...
> > The exiting data is not only compelling, it's pretty much overwhelming.
>
> I'm glad you feel that way. Those of us who are actually qualified
> practicing engineers do not concur.
>

In what field of engineering?

[Matt Barrow]

"Michael" > wrote in message
ups.com...
> > The exiting data is not only compelling, it's pretty much overwhelming.
>
> I'm glad you feel that way. Those of us who are actually qualified
> practicing engineers do not concur.
>

Why?

Be specific and technical.


--
Matt

[Michael]

>>Why? Be specific and technical.

Where is your long-term field study comparing LOP and ROP operations?
How many engines have been monitored in service from start to overhaul,
under what conditions, and for how long? Have you shown a
statistically significant difference in MTBF, service life, or cost of
maintenance? That's really the only way to cover all bases. Sometimes
this is not practical, but lacking a long term field study, you at
least need a reasonable model. A compelling model would address the
following issues, as a minimum:

What are your parameters to asess engine roughness in normal LOP and
ROP operations? How do you model the imperfections caused by pilot
technique? Do you have amplitude and frequency data on engine
vibration at various mixture settings? What kind of sensors did you
use?

Do you have long term operational data or at least a model showing the
long term behaviour of the engine mounts, bearings, cases, crankshaft,
etc. under the vibration conditions? Without long-term operational
data, I would expect at least an FEA.

Do you have any information at all on the differences in combustion
end-products in excess-air vs. excess-fuel combustion reactions? I can
assure you they are differrent. Are any of the combustion products
harmful to the engine components long-term? Do any pose corrosion
issues when the aircraft is not flown for several days or weeks, as
commonly happens with private planes?

How about that big mixture pull - it takes the mixture through peak.
What is the effect of this transition on the crankshaft? Some analysis
of this issue was done in the 1940's, using the limited available tools
- but only for radial engines, which have significantly different
crankshaft designs. For that matter, about the only large base of
operational data in the LOP regime comes from radial engines - which
are different - using 1940's and 1950's fuels which were significantly
different than what you're burning now.

I'm sure given time I could think of other issues.

The main arguments for LOP operation are short-term economic ones -
less plug fouling, lower fuel burn. These are pretty compelling. As
for effect on TBO and general engine longevity, there has been much
hype and no compelling evidence.

BTW - to answer your other question - I run the R&D group for a major
manufacturer of industrial instrumentation. So yes, this is pretty
much right up my alley.

Michael

[Matt Barrow]

"Michael" > wrote in message
oups.com...
> >>Why? Be specific and technical.
>
> Where is your long-term field study comparing LOP and ROP operations?

> How many engines have been monitored in service from start to overhaul,
> under what conditions, and for how long? Have you shown a
> statistically significant difference in MTBF, service life, or cost of
> maintenance? That's really the only way to cover all bases. Sometimes
> this is not practical, but lacking a long term field study, you at
> least need a reasonable model. A compelling model would address the
> following issues, as a minimum:

It's been done.

> What are your parameters to asess engine roughness in normal LOP and
> ROP operations? How do you model the imperfections caused by pilot
> technique? Do you have amplitude and frequency data on engine
> vibration at various mixture settings? What kind of sensors did you
> use?

It's been done.

>
> Do you have long term operational data or at least a model showing the
> long term behaviour of the engine mounts, bearings, cases, crankshaft,
> etc. under the vibration conditions?

It's been done.

> Without long-term operational
> data, I would expect at least an FEA.

Five years of data.

> Do you have any information at all on the differences in combustion
> end-products in excess-air vs. excess-fuel combustion reactions?

Yes.

> I can
> assure you they are differrent. Are any of the combustion products
> harmful to the engine components long-term? Do any pose corrosion
> issues when the aircraft is not flown for several days or weeks, as
> commonly happens with private planes?

Non-sequitur.

>
> How about that big mixture pull - it takes the mixture through peak.
> What is the effect of this transition on the crankshaft? Some analysis
> of this issue was done in the 1940's, using the limited available tools
> - but only for radial engines, which have significantly different
> crankshaft designs. For that matter, about the only large base of
> operational data in the LOP regime comes from radial engines - which
> are different - using 1940's and 1950's fuels which were significantly
> different than what you're burning now.

Bull****.


> I'm sure given time I could think of other issues.
>
> The main arguments for LOP operation are short-term economic ones -
> less plug fouling, lower fuel burn.

Lower internal pressures, etc. All have been hypothesized, tested...

> These are pretty compelling. As
> for effect on TBO and general engine longevity, there has been much
> hype and no compelling evidence.

Bull****.

> BTW - to answer your other question - I run the R&D group for a major
> manufacturer of industrial instrumentation. So yes, this is pretty
> much right up my alley.

What sort of industry? Baed on that your only angle to comment on is about
the test bed at http://www.engineteststand.com

Not doing tests? A 64 point analysis tool, doing thousands of readings a
second?

I'm seeing something here besides naiveté on your part.

I'm claiming "Bull****" on your part.

[Michael]

>I'm seeing something here besides naivet=E9 on your part.

Ah, of course - anyone who disagrees with you must have ulterior
motives. Wrong again. I am NOT in the aviation industry (we provide
instrumentation to petroleum, refining, municipal water and wastewater,
chemical, metals, mining and dredging, and other industries - but not
aviation) and the aircraft I own, I routinely operate LOP. I'm simply
not blinded by the hype as you are.

> I'm claiming "Bull****" on your part.

You're welcome to your opinion. You response pretty much demonstrates
that it's not an informed opinion.

I've been technical and specific. You haven't. If you expect to be
taken seriously, go back through your response and provide links where
you say it's been done, and an explanation where you call bull****. Be
technical and specific.

Michael

[Matt Barrow]

"Michael" > wrote in message
oups.com...
>>I'm seeing something here besides naiveté on your part.

NOTE: Seeing that the issue here has morphed from "scientific methods in the
lab" to "LOP being hype", I'll address the latter.

Michael implies that LOP is untested outside a laboratory. Much has been
informal field work. OTOH, much has been done in the "lab" -
http://www.engineteststand.com/ (You can watch in real time).

>Ah, of course - anyone who disagrees with you must have ulterior
>motives. Wrong again. I am NOT in the aviation industry (we provide
>instrumentation to petroleum, refining, municipal water and wastewater,
>chemical, metals, mining and dredging, and other industries

And that relates...how?

> - but not
>aviation)

So your qualifications do NOT correspond.

>and the aircraft I own, I routinely operate LOP.
> I'm simply
>not blinded by the hype

CHRIST-ON-A-BIKE, _why_? It's all HYPE, remember?
> as you are.

Oh, anyone who disagrees with you is blinded by hype. No, but your full of
it (or of yourself).

> I'm claiming "Bull****" on your part.
> You're welcome to your opinion. You response pretty much demonstrates
> that it's not an informed opinion.

Yours say nothing either. You make spurious claims of engineering expertise
that has virtually nothing to do with the issue.

Cut the attempts at intimidation, I've been intimadted by some real pros and
you're just a whelp compared to them.

> I've been technical and specific.

Bull****. You made numerous unsubstantiated assertions, not to mention
claims of expertise that are worthless.

Let's see what you've snipped:

:Where is your long-term field study comparing LOP and ROP operations?

Deakin's "Engine Series" provides:
http://www.avweb.com/news/columns/182146-1.html

See any of them about the combustion event and TDC.

:How many engines have been monitored in service from start to overhaul,
:under what conditions, and for how long? Have you shown a
:statistically significant difference in MTBF, service life, or cost of
:maintenance? That's really the only way to cover all bases. Sometimes
:this is not practical, but lacking a long term field study, you at
:least need a reasonable model.

See above, plus the history of TOH's...

: A compelling model would address the
: following issues, as a minimum:
: What are your parameters to asess engine roughness in normal LOP and
: ROP operations?

As mentioned earlier:
"These subjective reports were confirmed recently when Chadwick-Helmuth
spent several days running tests on a 1993 Beech F33A instrumented with one
of C-H's latest state-of-the-art vibration analyzers hooked to multiple
accelerometers and vibration transducers. Tests were flown at a wide range
of power settings and mixtures using a set of standard TCM nozzles, then
repeated after GAMIjectors were installed. The results indicated that the
GAMIjectors reduced vibration levels at the 2nd order frequency and at the
low 1/3rd order frequency by 60% to 80%.

I guess you conveniently missed that one, huh?

:How do you model the imperfections caused by pilot
:technique? Do you have amplitude and frequency data on engine
:vibration at various mixture settings? What kind of sensors did you
:use?

http://www.engineteststand.com/


:Do you have long term operational data or at least a model showing the
:long term behaviour of the engine mounts, bearings, cases, crankshaft,
:etc. under the vibration conditions? Without long-term operational
:data, I would expect at least an FEA.

http://www.engineteststand.com/ (Been running for several years).

:Do you have any information at all on the differences in combustion
:end-products in excess-air vs. excess-fuel combustion reactions? I can
:assure you they are differrent.

??? Nice tangent there!!!

: Are any of the combustion products
:harmful to the engine components long-term?

Like Lead Oxybromide? :~)

:Do any pose corrosion
:issues when the aircraft is not flown for several days or weeks, as
:commonly happens with private planes?

Not that what you ask has a damn thing to do with it, but, since you aren't
being specific, neither will I, so you can dig out the specifics:

http://www.avweb.com/news/columns/182132-1.html

http://www.avweb.com/news/columns/182149-1.html

:How about that big mixture pull - it takes the mixture through peak.
:What is the effect of this transition on the crankshaft?

http://www.avweb.com/news/columns/182084-1.html (Half way down...you can
correlate this to a crankshft, can't you?)

: Some analysis
:of this issue was done in the 1940's, using the limited available tools
:- but only for radial engines, which have significantly different
:crankshaft designs. For that matter, about the only large base of
:operational data in the LOP regime comes from radial engines - which
:are different - using 1940's and 1950's fuels which were significantly
:different than what you're burning now.



Wow!! That's real specific. Methodological, but NOT ONE PIECE OF DATA.

> You haven't. If you expect to be
> taken seriously, go back through your response and provide links where
> you say it's been done, and an explanation where you call bull****. Be
> technical and specific.

I fully expect, based on your response to questions of your assertions,
that's you'll provide a classic example of evasion.

http://www.avweb.com/news/reviews/182558-1.html (Data graphs
specifically...or are those faked?)

http://www.avweb.com/cgi-bin/udt/im.display.printable?client.id=avweb&story.id=182531
(data set one-fourth of the way down..or is that just fake hype?)


Charts, graphs, explanations all over the place in these.

http://www.avweb.com/news/columns/182155-1.html (Data through out)

----------
http://www.avweb.com/news/columns/182084-1.html


--------

> Michael

I'd really like to flesh this all out, and have the benefit of some real
expertise, for my benefit as well as the community. I suspect that, as
mentioned, Michael's not making much more than farts in the wind.

I also find a disconnect between the terms "science" and "engineering". Yes,
doing full blown lab test would be nice. Some of the data has been done in
the lab, a lab far more advanced than anything TCM Lycoming has ever done.
One tenant about science or engineering is that data must not contradict
other data. It doesn't.

Is all this as formal as a pristine laboratory? Hell no. Does it need to be?
Not hardly. I guess Lavoisier's and Priestly's work was worthless since they
didn't work in a formal lab. :~)

One of the defining characteristics of humans is the ability to
conceptualize and abstract. Try it.

(This is twice, now, that you've challenged without providing an ounce of
data. I expect some more SPIN...)


Matt
---------------------
Matthew W. Barrow, SCCE
Site-Fill Homes, LLC.
Montrose, CO

[Michael]

>>and the aircraft I own, I routinely operate LOP.
>> I'm simply
>>not blinded by the hype

>CHRIST-ON-A-BIKE, _why_? It's all HYPE, remember?

Because LOP saves fuel and keeps plugs clean. That much is proven. It
is a fact that lower combustion pressures are also proven - but how
this correlates to long term engine longevity is unknown.

>>Where is your long-term field study comparing LOP and ROP operations?
>Deakin's "Engine Series" provides:
>http://www.avweb.com/news/columns/182146-1.html
>See any of them about the combustion event and TDC.

None of that says ANYTHING about longevity - at least nothing provable.
Yes, the peak pressure is lower. So? Does the difference impact
longevity? Where is your model? Absent that, where is your long term
controlled field study?

>: What are your parameters to asess engine roughness in normal LOP and
>: ROP operations?

>As mentioned earlier:
>"These subjective reports were confirmed recently when Chadwick->Helmuth
>spent several days running tests on a 1993 Beech F33A instrumented with >one
>of C-H's latest state-of-the-art vibration analyzers hooked to multiple
>accelerometers and vibration transducers. Tests were flown at a wide >range
>of power settings and mixtures using a set of standard TCM nozzles, then
>repeated after GAMIjectors were installed. The results indicated that the
>GAMIjectors reduced vibration levels at the 2nd order frequency and at the
>low 1/3rd order frequency by 60% to 80%.

>I guess you conveniently missed that one, huh?

Not at all. I never said that GAMIjectors do not reduce vibration at
equivalent operating conditions. The test you refer to is a validation
of a product, not an operating regime. It shows that regardless of
what you do in terms of operating a given TCM engine (and note - this
is ONE engine) it does better with GAMI's. No argument. The question
is whether it does better LOP or ROP with the same injectors, and this
test does not give you that information.

>:How do you model the imperfections caused by pilot
>:technique? Do you have amplitude and frequency data on engine
>:vibration at various mixture settings? What kind of sensors did you
>:use?
>http://www.engineteststand.com/

Oh no you don't. Be technical and specific. What is the model? Where
is it specifically? What assumptions does it make?

>:Do you have long term operational data or at least a model showing the
>:long term behaviour of the engine mounts, bearings, cases, crankshaft,
>:etc. under the vibration conditions? Without long-term operational
>:data, I would expect at least an FEA.
>http://www.engineteststand.com/ (Been running for several years).

How many engines? How many installations? And what kind? Be technical
and specific. Explain why that one given installation should be
considered proof for all (or even most).

>:Do you have any information at all on the differences in combustion
>:end-products in excess-air vs. excess-fuel combustion reactions? I can
>:assure you they are differrent.
>??? Nice tangent there!!!

Not a tangent at all. Since corrosion takes down a lot more engines
than wear on personal aircraft, it's a major issue.

>: Are any of the combustion products
>:harmful to the engine components long-term?
>Like Lead Oxybromide? :~)

Maybe. Maybe others. See, unless you have a statistically significant
sample of engines being run under controlled conditiions long enough to
establish MTBF, you don't really know WHAT the real issue is, so it's
your responsibility to cover all the bases if you want to claim
anything resembling compelling evidence.

> Wow!! That's real specific. Methodological, but NOT ONE PIECE OF DATA.

No, there isn't one piece of data. But then I'm not the one claiming
compelling evidence exists, one way or the other. I in fact claim just
the opposite - that no compelling evidence exists one way or the other.
There are some very compelling short-term reasons to operate LOP (save
fuel, don't have to clean the spark plugs as often) and no real
evidence one way or the other what happens in the long term

The people who claim LOP is harmful in the long term are whistling in
the wind too.

> I fully expect, based on your response to questions of your assertions,
> that's you'll provide a classic example of evasion.
> http://www.avweb.com/news/reviews/182558-1.html (Data graphs
> specifically...or are those faked?)

Not faked - just not relevant. They show no long term trends in
operation. Where are your graphs showing maintenance costs year by
year? Failures year by year?

>This is twice, now, that you've challenged without providing an ounce of
data. I expect some more SPIN...

You're really not getting it. I have NO data. Anywhere. I don't
think it exists. What you've shown is data all right - but not data
you can use to project MTBF or TBO or maintenance cost.

The number we're going for is this:

An engine operated LOP (making certain assumptions about how it will be
operated) will have an hourly operating cost of x% (less/more) than an
identical engine operated ROP (making the same assumptions about the
pilot's ability to consistently control the engine, and if the LOP
engine has GAMI's, so does the ROP engine) excluding fuel (where the
case has already been made quite adequately) but including parts
replacement, overhaul, etc.

Now show me what x is, how it was derived, and what assumptions were
involved.

Michael

[Matt Barrow]

"Michael" > wrote in message
ups.com...
> >>and the aircraft I own, I routinely operate LOP.
> >> I'm simply
> >>not blinded by the hype
>
> >CHRIST-ON-A-BIKE, _why_? It's all HYPE, remember?
>
> Because LOP saves fuel and keeps plugs clean. That much is proven. It
> is a fact that lower combustion pressures are also proven - but how
> this correlates to long term engine longevity is unknown.

DUH!!! And you're an engineer? HAHAHAHAHAHAH...

ALB

[Dan Luke]

"Matt Barrow" wrote:
>> >CHRIST-ON-A-BIKE, _why_? It's all HYPE, remember?
>>
>> Because LOP saves fuel and keeps plugs clean. That much is proven. It
>> is a fact that lower combustion pressures are also proven - but how
>> this correlates to long term engine longevity is unknown.
>
> DUH!!! And you're an engineer? HAHAHAHAHAHAH...

Evasion by ad hominem noted.

> ALB

Running away noted.

[Greg Copeland]

On Wed, 20 Jul 2005 07:25:09 -0700, Matt Barrow wrote:

>
> "Michael" > wrote in message
> ups.com...
>> >>and the aircraft I own, I routinely operate LOP.
>> >> I'm simply
>> >>not blinded by the hype
>>
>> >CHRIST-ON-A-BIKE, _why_? It's all HYPE, remember?
>>
>> Because LOP saves fuel and keeps plugs clean. That much is proven. It
>> is a fact that lower combustion pressures are also proven - but how
>> this correlates to long term engine longevity is unknown.
>
> DUH!!! And you're an engineer? HAHAHAHAHAHAH...

Don't forget that there is no correlation between reduced vibration and
increased longevity.... Hehe.... Oh wait...that only validates a product
(and its principles), not the principal it self. Hmmm...

[Greg Copeland]

On Sat, 16 Jul 2005 02:51:27 +0000, bill hunter wrote:

[snip]
> I change altitudes a lot, and tend to fly high when weather permits. I
> also have a turbo arrow with a very sensitive throttle that needs to be
> adjusted continuously during climbs and decent. I don't need the
> aggravation of having to adjust the mixture 3 times as much because I
> was LOP. I know during the 2000 hours I would eventually get distracted
> in busy airspace, and end up running too close to peek during a cruise
> climb.


I thought LOP was not recommended for turbo applications?

[Greg Copeland]

On Fri, 15 Jul 2005 11:27:54 -0700, Michael wrote:

>> The extra vibration occurs only if you don't have proper fuel
>> distribution LOP
[snip]
>
> Of course all the piston airliners routinely ran LOP - but it's
> important to remember that over the course of its life, the cost of
> fuel the engine burns is significantly higher than the cost of the
> overhaul - and thus LOP operation, which can easily save 10-15% for the
> same power and speed, can be economically advantageous even if it does
> measurably shorten engine life.
>
> Michael

This seems like one of the most straight forward and reasonable statements
you've made thus far. That's a good point. A very good point. Have
anything which validates that's the real reason they ran LOP?

[Matt Barrow]

"Greg Copeland" > wrote in message
...
> On Sat, 16 Jul 2005 02:51:27 +0000, bill hunter wrote:
>
> [snip]
> > I change altitudes a lot, and tend to fly high when weather permits. I
> > also have a turbo arrow with a very sensitive throttle that needs to be
> > adjusted continuously during climbs and decent. I don't need the
> > aggravation of having to adjust the mixture 3 times as much because I
> > was LOP. I know during the 2000 hours I would eventually get distracted
> > in busy airspace, and end up running too close to peek during a cruise
> > climb.
>
>
> I thought LOP was not recommended for turbo applications?
>

See Deakin's series, "Those Fire-Breathing Turbo's", parts 1-6.

http://www.avweb.com/news/columns/182146-1.html

[Matt Barrow]

"Greg Copeland" > wrote in message
...
> On Fri, 15 Jul 2005 11:27:54 -0700, Michael wrote:
>
> >> The extra vibration occurs only if you don't have proper fuel
> >> distribution LOP
> [snip]
> >
> > Of course all the piston airliners routinely ran LOP - but it's
> > important to remember that over the course of its life, the cost of
> > fuel the engine burns is significantly higher than the cost of the
> > overhaul - and thus LOP operation, which can easily save 10-15% for the
> > same power and speed, can be economically advantageous even if it does
> > measurably shorten engine life.
> >
> > Michael
>
> This seems like one of the most straight forward and reasonable statements
> you've made thus far. That's a good point. A very good point. Have
> anything which validates that's the real reason they ran LOP?

Less fuel, cleaner, better internal pressures...all things that make for
BETTER TBO. Some of the airlines were running their radial engines to
3500-4000 hrs between overhauls.

[Matt Barrow]

"Dan Luke" > wrote in message
...
>
> "Matt Barrow" wrote:
> >> >CHRIST-ON-A-BIKE, _why_? It's all HYPE, remember?
> >>
> >> Because LOP saves fuel and keeps plugs clean. That much is proven. It
> >> is a fact that lower combustion pressures are also proven - but how
> >> this correlates to long term engine longevity is unknown.
> >
> > DUH!!! And you're an engineer? HAHAHAHAHAHAH...
>
> Evasion by ad hominem noted.
>
> > ALB
>
> Running away noted.

Mental deficiency noted.


--
Matt
---------------------
Matthew W. Barrow
Site-Fill Homes, LLC.
Montrose, CO