LOP operation

Hey Charles,

If your reading is better than your Cessna model number knowledge, be aware
that I've always maintained GAMIs and Turbo engines are a good deal. A
Cessna 410(sic) is turbocharged. For normally aspirated engines, however,
their benefit is greatly diminished by the FACT that LOP reduces power,
especially where you need it most---at cruise at altitude.

*****Once again, not necessarily. Once the GAMI injectors are installed,
Deakin has been able to lean right to the point of having the engine
quit due to a mixture too lean to fire, without any roughness at all.
If there's roughness then the injectors are not matched properly.*****

That is just simply incorrect. There is roughness that anyone, including
Deakin and Braly notice. It has nothing to do with the injectors being
mismatched. It has everything to do with the need for the engine's timing to
be adjustable. LOP REQUIRES the timing to be further advanced. GAMI knows
this, and is the reason they are developing their Prism system of engine
management.

Best,




And
wrote in message
...
On Wed, 14 Apr 2004 22:36:41 -0700, "kage"
wrote:

Even John Deakin burned out a set of
Continental cylinders in 500 hours LOP in his Bonanza. And their highly
touted fuel savings are, for the most part, due to a decrease in speed.
You
know, all that drag increase with V squared.

I'd hesitate to speak for Mr. Deakin but I'd venture that he'd
disagree violently that running lean of peak burned out his cylinders.
Since running lean of peak results in low temperatures and less gas
being burned, how exactly did they get burned out?

To demonstrate that running lean of peak does not necessarily mean a
lost of power, his "Mixture Magic" column showed a color photo of an
instrument panel of a Cessna 410 running one engine ROP and the other
LOP. Both engines were producing exactly the same power but at
different manifold pressures. The LOP engine was using less fuel and
was running at lower CHT temps. How is that bad?

CHTs are just fine ROP.

Actually they aren't, if you set the engine according to the POH.
Running at 75% or 80% power and set 50 degrees ROP, the CHT's run
above 400 degrees. These are figures that come from Lycoming and
Continental. And yet over 400 degrees is where aluminum begins to
loose strength. Deakin also was able to demonstrate that at certain
POH dictated ROP settings, the cylinders actually distorted from the
heat and began to scuff the pistons. This was during flight testing
with several proprietary probes installed in his engine which could
read what was happening in areas away from the cylinderhead probe.
While these probes were showing alarming increases in heat, the
cylinderhead readings read normal. He had to terminate the testing at
those settings because the readings at the bases of the cylinders were
rapidly rising, indicating that the pistons were beginning to scuff.

Engines run clean enough ROP.
Engine stresses have been doing just fine now for 100 years ROP.
CO is not a problem in maintained exhaust systems.
Airplanes fly faster ROP.

Not necessarily. Same rpm, same airspeed but higher manifold pressure
at the LOP settings equals the same cruise speed. Yes, if you want to
fly at best power, you should be running ROP.

Even the LOP diehards admit engines run smoother ROP.
Gamis have more value in a turbocharged engine.

Once again, not necessarily. Once the GAMI injectors are installed,
Deakin has been able to lean right to the point of having the engine
quit due to a mixture too lean to fire, without any roughness at all.
If there's roughness then the injectors are not matched properly.

Corky Scott

On Thu, 15 Apr 2004 20:53:48 -0700, "kage"
wrote:

*****Once again, not necessarily. Once the GAMI injectors are installed,
Deakin has been able to lean right to the point of having the engine
quit due to a mixture too lean to fire, without any roughness at all.
If there's roughness then the injectors are not matched properly.*****

That is just simply incorrect. There is roughness that anyone, including
Deakin and Braly notice. It has nothing to do with the injectors being
mismatched. It has everything to do with the need for the engine's timing to
be adjustable. LOP REQUIRES the timing to be further advanced. GAMI knows
this, and is the reason they are developing their Prism system of engine
management.

Best,

According to Deakin's article "Mixture Magic", the speed at which the
fuel air mixture burns varies depending on the stochiometric ratio.
At the ideal mixture ratio of about 15 to 1 by volume, the mixture
burns fastest. On either side of that ratio, the burning slows down.

Because the timing is fixed, adjusting the mixture is the only way to
vary where the Peak Pressure Point (the point at which the combustion
process produces the highest pressure within the cylinder. It's
important that this occur when the crankshaft throw is about 16
degrees past TDC so that maximum leverage is applied to the piston.
If PPP occurs when the piston is closer to TDC, there is little
mechanical advantage and the pressure of the combustion pushes against
a piston that just pushes back instead of accelerating away and adding
thrust to the rotation of the crankshaft). The timing of the engines
and the mixture setup (full rich) is specifically adjusted such that
during full power operation, the PPP occurs at about 16 degrees past
top dead center. This is the source of the common knowledge that a
rich mixture cools the engine. The rich mixture doesn't hose down the
inside of the combustion chamber, it merely slows down the rate of
burning such that PPP occurs at 16 degrees past top dead center. When
the mixture is leaned out so that it approaches the ideal burning
ratio, the mixture burns faster and the PPP begins to occur while the
piston is much closer to TDC. This increases the pressure inside the
combustion chamber and heat goes up. This is the "peak" part of the
LOP or ROP operation. Either side of "peak" the mixture burns slower
which allows the engine to run cooler.

But lean the mixture further, beyond the ideal, and the rate of burn,
as mentioned above, slows down. This allows the piston to be at 16
degrees past TDC again which greatly reduces heat. It also reduces
the amount of gas you use.

As Deakin points out, at about 8,000 feet and full throttle, the
engine is only producing about 60% power and at that power setting you
cannot hurt the engine no matter where you put the mixture, so you
might as well lean to best power setting (which is rich of peak) and
leave it there, if you want to fly at your fastest cruise speed and
range is not an issue.

If the timing ***COULD*** be varied, there would be no need for a
mixture control knob, it could be set for best ratio by the mechanic
and the variable timing would take care of keeping the PPP at the
proper location. Variable timing would also simplify starting.
Engines start much easier when the timing can be retarded to fire the
plugs when the piston is at about TDC, or perhaps even a little after
TDC.

So in answer to your last statement above, LOP operation does not
require that the timing be further advanced. LOP operation actually
has the affect of retarding the timing because it slows down the
combustion process just as an over-rich mixture likewise slows down
the combustion process, allowing the PPP to occur in the desired
place.

Corky Scott

*****So in answer to your last statement above, LOP operation does not
require that the timing be further advanced. LOP operation actually
has the affect of retarding the timing because it slows down the
combustion process just as an over-rich mixture likewise slows down
the combustion process, allowing the PPP to occur in the desired
place.*******


Oh GREAT. Tell that ot GAMI. They can stop their work on PRISM right away.


wrote in message
...
On Thu, 15 Apr 2004 20:53:48 -0700, "kage"
wrote:

*****Once again, not necessarily. Once the GAMI injectors are installed,
Deakin has been able to lean right to the point of having the engine
quit due to a mixture too lean to fire, without any roughness at all.
If there's roughness then the injectors are not matched properly.*****

That is just simply incorrect. There is roughness that anyone, including
Deakin and Braly notice. It has nothing to do with the injectors being
mismatched. It has everything to do with the need for the engine's timing
to
be adjustable. LOP REQUIRES the timing to be further advanced. GAMI knows
this, and is the reason they are developing their Prism system of engine
management.

Best,

According to Deakin's article "Mixture Magic", the speed at which the
fuel air mixture burns varies depending on the stochiometric ratio.
At the ideal mixture ratio of about 15 to 1 by volume, the mixture
burns fastest. On either side of that ratio, the burning slows down.

Because the timing is fixed, adjusting the mixture is the only way to
vary where the Peak Pressure Point (the point at which the combustion
process produces the highest pressure within the cylinder. It's
important that this occur when the crankshaft throw is about 16
degrees past TDC so that maximum leverage is applied to the piston.
If PPP occurs when the piston is closer to TDC, there is little
mechanical advantage and the pressure of the combustion pushes against
a piston that just pushes back instead of accelerating away and adding
thrust to the rotation of the crankshaft). The timing of the engines
and the mixture setup (full rich) is specifically adjusted such that
during full power operation, the PPP occurs at about 16 degrees past
top dead center. This is the source of the common knowledge that a
rich mixture cools the engine. The rich mixture doesn't hose down the
inside of the combustion chamber, it merely slows down the rate of
burning such that PPP occurs at 16 degrees past top dead center. When
the mixture is leaned out so that it approaches the ideal burning
ratio, the mixture burns faster and the PPP begins to occur while the
piston is much closer to TDC. This increases the pressure inside the
combustion chamber and heat goes up. This is the "peak" part of the
LOP or ROP operation. Either side of "peak" the mixture burns slower
which allows the engine to run cooler.

But lean the mixture further, beyond the ideal, and the rate of burn,
as mentioned above, slows down. This allows the piston to be at 16
degrees past TDC again which greatly reduces heat. It also reduces
the amount of gas you use.

As Deakin points out, at about 8,000 feet and full throttle, the
engine is only producing about 60% power and at that power setting you
cannot hurt the engine no matter where you put the mixture, so you
might as well lean to best power setting (which is rich of peak) and
leave it there, if you want to fly at your fastest cruise speed and
range is not an issue.

If the timing ***COULD*** be varied, there would be no need for a
mixture control knob, it could be set for best ratio by the mechanic
and the variable timing would take care of keeping the PPP at the
proper location. Variable timing would also simplify starting.
Engines start much easier when the timing can be retarded to fire the
plugs when the piston is at about TDC, or perhaps even a little after
TDC.

So in answer to your last statement above, LOP operation does not
require that the timing be further advanced. LOP operation actually
has the affect of retarding the timing because it slows down the
combustion process just as an over-rich mixture likewise slows down
the combustion process, allowing the PPP to occur in the desired
place.

Corky Scott

On Fri, 16 Apr 2004 06:54:49 -0700, "kage"
wrote:

*****So in answer to your last statement above, LOP operation does not
require that the timing be further advanced. LOP operation actually
has the affect of retarding the timing because it slows down the
combustion process just as an over-rich mixture likewise slows down
the combustion process, allowing the PPP to occur in the desired
place.*******


Oh GREAT. Tell that ot GAMI. They can stop their work on PRISM right away.

I guess I don't understand your remark. What I've been explaining is
that GAMI has been saying. The fact that a lean or rich mixture burns
more slowly than the ideal mixture isn't made up, it's what happens
inside air cooled certified aircraft engines with fixed timing.

Why would GAMI want to stop work on their variable timing electronic
ignition?

Corky Scott

Howdy!

In article ,
kage wrote:
Hey Charles,

If your reading is better than your Cessna model number knowledge, be aware
that I've always maintained GAMIs and Turbo engines are a good deal. A
Cessna 410(sic) is turbocharged. For normally aspirated engines, however,
their benefit is greatly diminished by the FACT that LOP reduces power,
especially where you need it most---at cruise at altitude.

*****Once again, not necessarily. Once the GAMI injectors are installed,
Deakin has been able to lean right to the point of having the engine
quit due to a mixture too lean to fire, without any roughness at all.
If there's roughness then the injectors are not matched properly.*****

That is just simply incorrect. There is roughness that anyone, including
Deakin and Braly notice. It has nothing to do with the injectors being
mismatched. It has everything to do with the need for the engine's timing to
be adjustable. LOP REQUIRES the timing to be further advanced. GAMI knows
this, and is the reason they are developing their Prism system of engine
management.

Are you calling John Deakin a liar? It sure looks that way.

Listen, howzabout you provide us with some way to verify your claims besides
taking your word for it. Links to verifiable accounts, etc.

yours,
Michael


--
Michael and MJ Houghton | Herveus d'Ormonde and Megan O'Donnelly
| White Wolf and the Phoenix
Bowie, MD, USA | Tablet and Inkle bands, and other stuff
| http://www.radix.net/~herveus/

Hi Corky,

Even John Deakin burned out a set of
Continental cylinders in 500 hours LOP in his Bonanza. And their
highly
touted fuel savings are, for the most part, due to a decrease in
speed. You
know, all that drag increase with V squared.

I'd hesitate to speak for Mr. Deakin but I'd venture that he'd
disagree violently that running lean of peak burned out his
cylinders.

Even if it did - Mr. Deakin is one of the key people in developing LOP
operations for today's GA Piston Aircraft. I guess he did experiment a
bit with it before getting it right.

However I fully agree: If done right running LOP puts less (thermal)
stress on the engine and is certainly not going to "burn out"
cylinders.

regards,
Friedrich

--
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