Confused about Lean of Peak (LOP) Operations?
The folks at
Advanced Pilot Seminars
can teach you more about why flying your engine "Green" of
Peak is the best operating decision you can possibly make for the health of your
engine!
The folks at Advanced Pilot Seminars even have an
on-line course that you can purchase to get yourself
educated on what's really happening in the internal combustion event. People say
it's like "Myth Busters" for the operation of the piston aircraft
engine!
Check out this
LOP PowerPoint Presentation and this
EGT Leaning Presentation created
by
Advanced Pilot Seminars
for a
good grounding in why this is the most efficient and effective operating
technique for your air cooled horizontally opposed aircraft engine.
Check out the GAMI injectors page
HERE
Check out this
Engine Management Article written by Peter Holt
Below are pics of my spark plugs after 200
hours of Lean of Peak Operations. No self respecting CSOB wants to break or
damage anything expensive and that's a big part of why I run my B55 Baron LOP. The folks
running ROP are just kidding themselves and running their engines at the highest
internal combustion pressures possible (and also the highest CHTs).
Removing the fuel past peak EGT does not
melt cylinders, how the heck can removing the source of combustion energy do
anything but remove the intensity of the fire! Your CHTs will be lower and
that's a good thing for your cylinders.
Baron Owner and IA Stuart S. offers the
following simplified explanation of LOP operations:
"The combustion event begins with the spark
and the peak pressure occurs milliseconds later. LOP adds a bit of time to the
event. The higher the RPM, the further past TDC that the peak internal
combustion pressure occurs (ICP), resulting in less CHT."
This is another good reason to climb to your
cruise altitude at maximum continuous RPM!
LOP is so easy a Caveman could do it <grins>
See John Deakin's LOP guidance
HERE
Here's the rough math on my LOP operations:
Give up ~3% of airspeed and receive about ~16% better range or fuel economy!
To me, that's a great deal.
That's like getting 16 gallons of free fuel for every 100 gallons you burn! Or,
on a massive headwind cross country trip not having to make that fuel stop. PLUS
all the other advantages of lean and clean burning combustion operations inside
your engine.
Here are pics of my Exhaust stacks after a 5 hour LOP flight from KATW to KDTO
Left Engine IO-470L
Right Engine IO-470L
Here is their infamous
"Red Box" mixture vs. altitude diagram. Their recommendation is to
avoid operations in the "Red Box". Note that above 8,000' the Red Box
does not exist! You cannot hurt a normally aspirated engine with your mixture
settings at altitudes above 8,000'.
Still confused? Click the link above for their
seminar or on-line course.
Learn to use this KNOB!
The Dangerous Red Box
Just where is that "red box" John Deakin keeps talking about? Some rough
numbers, good (that is to say, BAD) for most of these engines -- these are
"no fly zones," DO NOT set the mixture between them:
Red Box = No Fly Zone
- At and below about 60% power, there is no red box. Put the mixture
wherever you want it.
- 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.
All those numbers are approximate! Please don't start splitting hairs,
here!
You probably don't want to run your engine between those mixture
settings. If you do, you are running very high peak pressures inside the
combustion chambers, and that peak pressure is occurring too close to top
dead center.
There's a chance you read too fast, and missed this very important point,
so let me put it another way:
Outside the Box
- At 65% power, use richer than 100 ROP, or leaner than peak EGT.
- At 70%, use richer than 125ºF ROP, or leaner than 25ºF LOP.
- At 75%, use richer than 180ºF ROP, or leaner than 40ºF LOP.
- At 80%, use richer than 200ºF ROP, or leaner than 60ºF LOP.
On most of these engines, with a properly set mixture at full rich, at
sea level, full power, the EGT ends up at about 250ºF ROP, with some as high
as 300ºF ROP and temps of 1250-1300F on most EGT monitoring equipment.
Lean of Peak Operation For IO-550 |
|
Lean of Peak Operation For IO-520 |
GPH |
HP |
GPH |
HP |
GPH |
HP |
|
GPH |
HP |
GPH |
HP |
GPH |
HP |
10.0 |
50% |
13.0 |
65% |
16.0 |
79% |
|
10.0 |
52% |
13.0 |
68% |
16.0 |
84% |
10.2 |
51% |
13.2 |
66% |
16.2 |
80% |
|
10.2 |
53% |
13.2 |
69% |
16.2 |
85% |
10.4 |
52% |
13.4 |
67% |
16.4 |
81% |
|
10.4 |
54% |
13.4 |
70% |
16.4 |
86% |
10.6 |
53% |
13.6 |
68% |
16.6 |
82% |
|
10.6 |
55% |
13.6 |
71% |
16.6 |
87% |
10.8 |
54% |
13.8 |
69% |
16.8 |
83% |
|
10.8 |
56% |
13.8 |
72% |
16.8 |
88% |
11.0 |
55% |
14.0 |
70% |
17.0 |
84% |
|
11.0 |
58% |
14.0 |
73% |
17.0 |
89% |
11.2 |
56% |
14.2 |
71% |
17.2 |
85% |
|
11.2 |
59% |
14.2 |
74% |
17.2 |
90% |
11.4 |
57% |
14.4 |
72% |
17.4 |
86% |
|
11.4 |
60% |
14.4 |
75% |
17.4 |
91% |
11.6 |
58% |
14.6 |
73% |
17.6 |
87% |
|
11.6 |
61% |
14.6 |
76% |
17.6 |
92% |
11.8 |
59% |
14.8 |
74% |
17.8 |
88% |
|
11.8 |
62% |
14.8 |
77% |
17.8 |
93% |
12.0 |
60% |
15.0 |
75% |
18.0 |
89% |
|
12.0 |
63% |
15.0 |
78% |
18.0 |
94% |
12.2 |
61% |
15.2 |
75% |
18.2 |
90% |
|
12.2 |
64% |
15.2 |
79% |
18.2 |
95% |
12.4 |
62% |
15.4 |
76% |
18.4 |
91% |
|
12.4 |
65% |
15.4 |
81% |
18.4 |
96% |
12.6 |
63% |
15.6 |
77% |
18.6 |
92% |
|
12.6 |
66% |
15.6 |
82% |
18.6 |
97% |
12.8 |
64% |
15.8 |
78% |
18.8 |
93% |
|
12.8 |
67% |
15.8 |
83% |
18.8 |
98% |
|
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|
Conversion Factor |
14.9 |
|
|
|
|
Conversion Factor |
14.9 |
|
|
|
Max HP |
|
300 |
|
|
|
|
Max HP |
|
285 |
|
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ROP Percent Horsepower Chart |
|
RPM |
MP |
2700 |
2600 |
2500 |
2400 |
2300 |
2200 |
29 |
100.0 |
97.5 |
95.0 |
92.5 |
90.0 |
87.5 |
28 |
96.5 |
94.0 |
91.5 |
89.0 |
86.5 |
84.0 |
27 |
93.0 |
90.5 |
88.0 |
85.5 |
83.0 |
80.5 |
26 |
89.5 |
87.0 |
84.5 |
82.0 |
79.5 |
77.0 |
25 |
86.0 |
83.5 |
81.0 |
78.5 |
76.0 |
73.5 |
24 |
82.5 |
80.0 |
77.5 |
75.0 |
72.5 |
70.0 |
23 |
79.0 |
76.5 |
74.0 |
71.5 |
69.0 |
66.5 |
22 |
75.5 |
73.0 |
70.5 |
68.0 |
65.5 |
63.0 |
21 |
72.0 |
69.5 |
67.0 |
64.5 |
62.0 |
59.5 |
20 |
68.5 |
66.0 |
63.5 |
61.0 |
58.5 |
56.0 |
|
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Charts Courtesy of Beech
Lister Elliott S.
|