Gene Whitt is back on line

50 RPM drop on the rich side is too rich at cruise... 50
degrees rich of peak on the EGT is about right with a carb.
With fuel injection, just a little below peak or even at
peak if the cruise power is set below 70%. At low power
settings you can run at peak since the actual temperatures
will be low. If you have a calibrated EGT (TIT) follow the
limits.


--
James H. Macklin
ATP,CFI,A&P

--
The people think the Constitution protects their rights;
But government sees it as an obstacle to be overcome.
some support
http://www.usdoj.gov/olc/secondamendment2.htm
See http://www.fija.org/ more about your rights and duties.


"Jose" wrote in message
. net...
| Standard procedures in many (most?) places says 50 or so
ROP...about the
| worst place you can run your engine.
|
| If it really =is= the worst place, how did the engine
makers come to
| reccomend it?
|
| Jose
| --
| Money: what you need when you run out of brains.
| for Email, make the obvious change in the address.

Jim,

50 RPM drop on the rich side is too rich at cruise... 50
degrees rich of peak on the EGT is about right with a carb.
With fuel injection, just a little below peak or even at
peak if the cruise power is set below 70%. At low power
settings you can run at peak since the actual temperatures
will be low. If you have a calibrated EGT (TIT) follow the
limits.


Ok, kids, now lets count all the misunderstandings and factually wrong
statements in that post. Hint: There are at least 5.

--
Thomas Borchert (EDDH)

You tell us.

If I'm wrong I'd like to know.


"Thomas Borchert" wrote in
message ...
| Jim,
|
| 50 RPM drop on the rich side is too rich at cruise... 50
| degrees rich of peak on the EGT is about right with a
carb.
| With fuel injection, just a little below peak or even at
| peak if the cruise power is set below 70%. At low power
| settings you can run at peak since the actual
temperatures
| will be low. If you have a calibrated EGT (TIT) follow
the
| limits.
|
|
| Ok, kids, now lets count all the misunderstandings and
factually wrong
| statements in that post. Hint: There are at least 5.
|
| --
| Thomas Borchert (EDDH)
|

Jim,

50 RPM drop on the rich side is too rich at cruise...

RPM doesn't matter.

50
degrees rich of peak on the EGT is about right with a carb.

Why? How? 50 ROP is the point of maximum internal combustion pressure.
A point at which you don't really want to be.

With fuel injection, just a little below peak or even at
peak if the cruise power is set below 70%.

below peak on the rich or the lean side? A limit of 70 is artificial.
65 and 75 is mentioned by the engine manufacturers, respectively. Many
say those limits don't mean that much. CHTs do. Many people run their
engines lean of peak (well lean of peak) at 80 percent and more. CHTs
stay well below 380.
There is no difference in leaning technique between carb'd and injected
engines.

At low power
settings you can run at peak since the actual temperatures
will be low.

What temperatures? EGT? CHT? Actual EGTs don't matter anyway. Actual
CHTs are higher ROP than they are at peak EGT. They shouldn't be above
380.

If you have a calibrated EGT (TIT) follow the
limits.

Absolute EGTs don't matter. TIT is a different story, since the engine
is turbo'd.

I really recommend reading Deakin's columns at Avweb - it makes you see
several lights real quick.

--
Thomas Borchert (EDDH)

If you set cruise RPM to 2400 and lean the engine, RPM will
increase as combustion is improved and power increases
(fixed pitch prop). Peak power is max RPM, some books
recommend running richer, enough to drop the RPM 50. Ground
idle mixture is set so that RPM increases 20-50 RPM as the
engine goes from rich idle to cutoff and the mixture leans
out.


"Thomas Borchert" wrote in
message ...
| Jim,
|
| 50 RPM drop on the rich side is too rich at cruise...
|
| RPM doesn't matter.
|
| 50
| degrees rich of peak on the EGT is about right with a
carb.
|
| Why? How? 50 ROP is the point of maximum internal
combustion pressure.
| A point at which you don't really want to be.
|
| With fuel injection, just a little below peak or even at
| peak if the cruise power is set below 70%.
|
| below peak on the rich or the lean side? A limit of 70 is
artificial.
| 65 and 75 is mentioned by the engine manufacturers,
respectively. Many
| say those limits don't mean that much. CHTs do. Many
people run their
| engines lean of peak (well lean of peak) at 80 percent and
more. CHTs
| stay well below 380.
| There is no difference in leaning technique between carb'd
and injected
| engines.
|
| At low power
| settings you can run at peak since the actual
temperatures
| will be low.
|
| What temperatures? EGT? CHT? Actual EGTs don't matter
anyway. Actual
| CHTs are higher ROP than they are at peak EGT. They
shouldn't be above
| 380.
|
| If you have a calibrated EGT (TIT) follow the
| limits.
|
| Absolute EGTs don't matter. TIT is a different story,
since the engine
| is turbo'd.
|
| I really recommend reading Deakin's columns at Avweb - it
makes you see
| several lights real quick.
|
| --
| Thomas Borchert (EDDH)
|

Jim,

Peak power is max RPM, some books
recommend running richer, enough to drop the RPM 50.


Do you have an example for a POH recommending that?

And do you think this procedure prepares your students for complex
aircraft adequately?

--
Thomas Borchert (EDDH)

"Jim Macklin" wrote in message
news:vslKf.100259$4l5.46897@dukeread05...
You tell us.

If I'm wrong I'd like to know.


Red Box = No Fly Zone
At and below about 60% power, there is no red box.
At about 65% power or so, 100ºF ROP to Peak.
At about 70%, 125ºF ROP to 25ºF LOP.
At about 75%, 180ºF ROP to 40ºF LOP.
At about 80%, 200ºF ROP to 60ºF LOP


Makes no difference, carb or fuel injection.

You might have been an A&P for the better part of 35 years, but you're just
parroting "Old Wives Tales"

http://www.avweb.com/news/columns/182155-1.html (Myths about fired valves)

http://www.avweb.com/news/columns/182149-1.html (Detonation myths)

Oh, hell...read the whole series
http://www.avweb.com/news/columns/182146-1.html



"Thomas Borchert" wrote in
message ...
| Jim,
|
| 50 RPM drop on the rich side is too rich at cruise... 50
| degrees rich of peak on the EGT is about right with a
carb.
| With fuel injection, just a little below peak or even at
| peak if the cruise power is set below 70%. At low power
| settings you can run at peak since the actual
temperatures
| will be low. If you have a calibrated EGT (TIT) follow
the
| limits.
|
|
| Ok, kids, now lets count all the misunderstandings and
factually wrong
| statements in that post. Hint: There are at least 5.
|
| --
| Thomas Borchert (EDDH)
|

50 RPM drop on the rich side is too rich at cruise.

I've never heard of leaning to an RPM drop... just to an EGT drop.

With fuel injection, just a little below peak or even at
peak if the cruise power is set below 70%.

Why is fuel injection different? More even mixtures across the cylinders?

Jose
--
Money: what you need when you run out of brains.
for Email, make the obvious change in the address.

Yes, engine roughness is caused by one cylinder misfiring.
Fuel injection is properly calibrated is the same on all
cylinders so the engine runs smooth and balanced.


"Jose" wrote in message
om...
| 50 RPM drop on the rich side is too rich at cruise.
|
| I've never heard of leaning to an RPM drop... just to an
EGT drop.
|
| With fuel injection, just a little below peak or even at
| peak if the cruise power is set below 70%.
|
| Why is fuel injection different? More even mixtures
across the cylinders?
|
| Jose
| --
| Money: what you need when you run out of brains.
| for Email, make the obvious change in the address.

Jim,

Yes, engine roughness is caused by one cylinder misfiring.

Not at all. Or rather: very rarely. Engine roughness which we normally
encounter during leaning is caused by the cylinders developing
different amounts of power.

Fuel injection is properly calibrated is the same on all
cylinders so the engine runs smooth and balanced.

TCM and Lycoming specs don't at all require that. Which is why
GAMIjectors are such a success. And no, GAMIjectors DON'T calibrate
fuel flow to be the same for each cylinder, since you don't want or
need that. What you need is the same fuel-air ratio in each cylinder.
So those cylinders that get less air need less fuel, too.

Read Deakin, it's all in there.

--
Thomas Borchert (EDDH)