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Kobra
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 Posted: Sat Apr 28, 2007 6:12 am Post subject: Fuel Flow and Peak EGT |
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Flyers,
While flying to FL from NJ last week I did what I always do and fly ROP by
75 to 100 degrees. This is how I was trained and my CFII is also my A&P /
IA.
I know enough about LOP to know I will not operate LOP without an engine
analyzer and probably GAMI injectors which I do not yet possess.
During the trip I was looking at my fuel computer and seeing an average FF
of 10.5 to 11.5 GPH at 6 to 7 thousand feet at about 22 to 23 inches MP and
2400 RPM at 75 degrees ROP.
I pulled my POH out and looked up the cruise performance numbers for those
parameters and those altitudes and I saw the recommended FF's. If I leaned
to the recommended FF's I was usually at peak EGT.
So my question is: Does Cessna advocate running at peak EGT in cruise? Or
if "advocate" is a strong word, are they at least saying "you can if you
want to" run at peak EGT in cruise? I've always heard that running at peak
EGT is bad for the top end of the engine.
Kobra |
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Dan Luke
Guest
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| Posted: Sat Apr 28, 2007 6:12 am Post subject: Re: Fuel Flow and Peak EGT |
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"Kobra" wrote:
| Quote: | While flying to FL from NJ last week I did what I always do and fly ROP by
75 to 100 degrees. This is how I was trained and my CFII is also my A&P /
IA.
I know enough about LOP to know I will not operate LOP without an engine
analyzer and probably GAMI injectors which I do not yet possess.
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You are wise to err on the side of caution, but it is possible to run LOP
without fear of damaging the engine if you limit power. At 65% or below, it
can be done safely without an analyzer.
| Quote: | During the trip I was looking at my fuel computer and seeing an average FF
of 10.5 to 11.5 GPH at 6 to 7 thousand feet at about 22 to 23 inches MP and
2400 RPM at 75 degrees ROP.
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What model engine? I often run LOP at those settings with a Lyc. O-360 F1A6.
| Quote: | I pulled my POH out and looked up the cruise performance numbers for those
parameters and those altitudes and I saw the recommended FF's. If I leaned
to the recommended FF's I was usually at peak EGT.
So my question is: Does Cessna advocate running at peak EGT in cruise? Or
if "advocate" is a strong word, are they at least saying "you can if you
want to" run at peak EGT in cruise? I've always heard that running at peak
EGT is bad for the top end of the engine.
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Depends on the % power you're making.
--
Dan
C172RG at BFM |
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Stan Prevost
Guest
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| Posted: Sat Apr 28, 2007 6:12 am Post subject: Re: Fuel Flow and Peak EGT |
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"Newps" <nowhere (AT) nowhere (DOT) com> wrote in message
news:dK-dnTS05-luNq_bnZ2dnUVZ_qiqnZ2d (AT) bresnan (DOT) com...
| Quote: |
Neither is necessary. I have neither in my Bo, just a regular single
point EGT. Mine runs great LOP. Yours may not without the GAMI's.
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How do you know you are LOP on all cylinders? |
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Newps
Guest
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| Posted: Sat Apr 28, 2007 6:12 am Post subject: Re: Fuel Flow and Peak EGT |
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Kobra wrote:
| Quote: | Flyers,
While flying to FL from NJ last week I did what I always do and fly ROP by
75 to 100 degrees. This is how I was trained and my CFII is also my A&P /
IA.
|
Ouch, ouch and double ouch. About the worst place to operate an engine.
| Quote: |
I know enough about LOP to know I will not operate LOP without an engine
analyzer and probably GAMI injectors which I do not yet possess.
|
Neither is necessary. I have neither in my Bo, just a regular single
point EGT. Mine runs great LOP. Yours may not without the GAMI's.
Remember anything at 65% and less power it doesn't matter where you put
the mixture, you cannot harm the engine.
| Quote: |
During the trip I was looking at my fuel computer and seeing an average FF
of 10.5 to 11.5 GPH at 6 to 7 thousand feet at about 22 to 23 inches MP and
2400 RPM at 75 degrees ROP.
I pulled my POH out and looked up the cruise performance numbers for those
parameters and those altitudes and I saw the recommended FF's. If I leaned
to the recommended FF's I was usually at peak EGT.
So my question is: Does Cessna advocate running at peak EGT in cruise? Or
if "advocate" is a strong word, are they at least saying "you can if you
want to" run at peak EGT in cruise? I've always heard that running at peak
EGT is bad for the top end of the engine.
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Do a Google search for Red Box. |
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Thomas Borchert
Guest
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| Posted: Sat Apr 28, 2007 2:18 pm Post subject: Re: Fuel Flow and Peak EGT |
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Kobra,
| Quote: | Does Cessna advocate running at peak EGT in cruise?
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Absolutely. That's what they call "best economy" setting, as opposed to "best
power", which is 75 or so ROP.
| Quote: | I've always heard that running at peak
EGT is bad for the top end of the engine.
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Have you, now? And the person(s) saying that have provided proof, numbers or
at least some kind of reasoning, I assume? Which goes how?
Don't fall for OWTs. The proper reaction to statements like that above is
"Show me the numbers!". If they can't, well, they're out. The LOP people can.
--
Thomas Borchert (EDDH) |
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Matt Barrow
Guest
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| Posted: Sat Apr 28, 2007 5:58 pm Post subject: Re: Fuel Flow and Peak EGT |
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"Kobra" <kobra (AT) yahoo (DOT) net> wrote in message
news:07GdnVYQ4b9BP6_bnZ2dnUVZ_segnZ2d (AT) comcast (DOT) com...
| Quote: | Flyers,
While flying to FL from NJ last week I did what I always do and fly ROP by
75 to 100 degrees. This is how I was trained and my CFII is also my A&P /
IA.
I know enough about LOP to know I will not operate LOP without an engine
analyzer and probably GAMI injectors which I do not yet possess.
|
If you keep running in that area (ROP) you might not have your engine long
enough to get those things.
How much would GAMIjectors and a Engine Analyzer cost compared to a top
overhaul (or worse)?
| Quote: |
During the trip I was looking at my fuel computer and seeing an average FF
of 10.5 to 11.5 GPH at 6 to 7 thousand feet at about 22 to 23 inches MP
and 2400 RPM at 75 degrees ROP.
|
Why did you (if it WAS you) install a fuel computer but not an engine
analyzer? A fuel computer is _nice_, but only if you fly your tanks close to
empty, but an EA is a _necessity_. A $3500 EA does wonders to protect a
$20K+ engine.
| Quote: |
I pulled my POH out and looked up the cruise performance numbers for those
parameters and those altitudes and I saw the recommended FF's. If I
leaned to the recommended FF's I was usually at peak EGT.
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http://www.avweb.com/newspics/194816_mixture_setting_triangle_graph-basic.gif |
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Newps
Guest
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| Posted: Sat Apr 28, 2007 10:36 pm Post subject: Re: Fuel Flow and Peak EGT |
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Stan Prevost wrote:
| Quote: | "Newps" <nowhere (AT) nowhere (DOT) com> wrote in message
news:dK-dnTS05-luNq_bnZ2dnUVZ_qiqnZ2d (AT) bresnan (DOT) com...
Neither is necessary. I have neither in my Bo, just a regular single
point EGT. Mine runs great LOP. Yours may not without the GAMI's.
How do you know you are LOP on all cylinders?
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I don't. Not necessary. |
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Matt Barrow
Guest
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| Posted: Sat Apr 28, 2007 11:03 pm Post subject: Re: Fuel Flow and Peak EGT |
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"Newps" <nowhere (AT) nowhere (DOT) com> wrote in message
news:i6KdnQlF9ru9G67bnZ2dnUVZ_rPinZ2d (AT) bresnan (DOT) com...
| Quote: |
Stan Prevost wrote:
"Newps" <nowhere (AT) nowhere (DOT) com> wrote in message
news:dK-dnTS05-luNq_bnZ2dnUVZ_qiqnZ2d (AT) bresnan (DOT) com...
Neither is necessary. I have neither in my Bo, just a regular single
point EGT. Mine runs great LOP. Yours may not without the GAMI's.
How do you know you are LOP on all cylinders?
I don't. Not necessary.
Not necessary if you don't mind burning up one or two jugs? |
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Newps
Guest
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| Posted: Sat Apr 28, 2007 11:31 pm Post subject: Re: Fuel Flow and Peak EGT |
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Matt Barrow wrote:
| Quote: | "Newps" <nowhere (AT) nowhere (DOT) com> wrote in message
news:i6KdnQlF9ru9G67bnZ2dnUVZ_rPinZ2d (AT) bresnan (DOT) com...
Stan Prevost wrote:
"Newps" <nowhere (AT) nowhere (DOT) com> wrote in message
news:dK-dnTS05-luNq_bnZ2dnUVZ_qiqnZ2d (AT) bresnan (DOT) com...
Neither is necessary. I have neither in my Bo, just a regular single
point EGT. Mine runs great LOP. Yours may not without the GAMI's.
How do you know you are LOP on all cylinders?
I don't. Not necessary.
Not necessary if you don't mind burning up one or two jugs?
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No such thing will happen. |
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Matt Barrow
Guest
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| Posted: Sun Apr 29, 2007 5:08 am Post subject: Re: Fuel Flow and Peak EGT |
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"Newps" <nowhere (AT) nowhere (DOT) com> wrote in message
news:YqGdnckCH4xID67bnZ2dnUVZ_uHinZ2d (AT) bresnan (DOT) com...
| Quote: |
Matt Barrow wrote:
"Newps" <nowhere (AT) nowhere (DOT) com> wrote in message
news:i6KdnQlF9ru9G67bnZ2dnUVZ_rPinZ2d (AT) bresnan (DOT) com...
Stan Prevost wrote:
"Newps" <nowhere (AT) nowhere (DOT) com> wrote in message
news:dK-dnTS05-luNq_bnZ2dnUVZ_qiqnZ2d (AT) bresnan (DOT) com...
Neither is necessary. I have neither in my Bo, just a regular single
point EGT. Mine runs great LOP. Yours may not without the GAMI's.
How do you know you are LOP on all cylinders?
I don't. Not necessary.
Not necessary if you don't mind burning up one or two jugs?
No such thing will happen.
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It will if the leanest is LOP, but one is still ROP. |
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Newps
Guest
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| Posted: Sun Apr 29, 2007 5:12 am Post subject: Re: Fuel Flow and Peak EGT |
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Matt Barrow wrote:
| Quote: | No such thing will happen.
It will if the leanest is LOP, but one is still ROP.
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I don't do that. |
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Thomas Borchert
Guest
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| Posted: Sun Apr 29, 2007 12:45 pm Post subject: Re: Fuel Flow and Peak EGT |
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Matt,
| Quote: | It will if the leanest is LOP, but one is still ROP.
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And the problem with that, at 75 percent or less power, is exactly
what?
--
Thomas Borchert (EDDH) |
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Matt Barrow
Guest
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| Posted: Mon Apr 30, 2007 1:42 am Post subject: Re: Fuel Flow and Peak EGT |
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"Newps" <nowhere (AT) nowhere (DOT) com> wrote in message
news:UdGdneTNm7xPf67bnZ2dnUVZ_tPinZ2d (AT) bresnan (DOT) com...
| Quote: |
Matt Barrow wrote:
No such thing will happen.
It will if the leanest is LOP, but one is still ROP.
I don't do that.
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How do you know?
Isn't that the point of a temp sensor on each and every cylinder? |
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Newps
Guest
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| Posted: Mon Apr 30, 2007 2:49 am Post subject: Re: Fuel Flow and Peak EGT |
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Matt Barrow wrote:
| Quote: | "Newps" <nowhere (AT) nowhere (DOT) com> wrote in message
news:UdGdneTNm7xPf67bnZ2dnUVZ_tPinZ2d (AT) bresnan (DOT) com...
Matt Barrow wrote:
No such thing will happen.
It will if the leanest is LOP, but one is still ROP.
I don't do that.
How do you know?
Isn't that the point of a temp sensor on each and every cylinder?
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One of the reasons, yes. But at 75% or less you don't use it for that. |
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Mike Noel
Guest
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| Posted: Mon Apr 30, 2007 4:29 am Post subject: Re: Fuel Flow and Peak EGT |
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That brings up an interesting point. I think the Lycoming recommendation
previously was <75% power for unrestricted leaning. Lately I have seen <65%
as a recommendation. Anyone have any background on the two different
limits?
I've noticed in my O-360-A1A that certain RPM settings (about 2450 in my
case) get a good EGT balance on all cylinders, and aggressive leaning
produces RPM and EGT drops without engine roughness. Is this what the gami
injected engines experience running LOP?
--
Best Regards,
Mike
http://photoshow.comcast.net/mikenoel
Macintosh - We might not get everything right, but at least we knew the
century was going to end.
"Newps" <nowhere (AT) nowhere (DOT) com> wrote in message
news:M5idnSgfMe1Tj6jbnZ2dnUVZ_hCdnZ2d (AT) bresnan (DOT) com...
| Quote: |
Matt Barrow wrote:
"Newps" <nowhere (AT) nowhere (DOT) com> wrote in message
news:UdGdneTNm7xPf67bnZ2dnUVZ_tPinZ2d (AT) bresnan (DOT) com...
Matt Barrow wrote:
No such thing will happen.
It will if the leanest is LOP, but one is still ROP.
I don't do that.
How do you know?
Isn't that the point of a temp sensor on each and every cylinder?
One of the reasons, yes. But at 75% or less you don't use it for that. |
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