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Date: Tue, 15 Oct 2013 07:53:25 -0400
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Subject: LOP ops on O-360 A1A
From: Keith Smith <keith.smith@gmail.com>
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Hey all,

I'm waiting for winter to come around but it seems like my O-360 A1A has
been running warmer than usual, requiring me to power back very shortly
after takeoff to avoid an excursion north of 425 degree CHT's.

In any case, I know that LOP ops are hard to come by with an O-360 due to
poor fuel distribution. Indeed, my #4 cylinder peaks well before the
others, making it tricky to get them LOP.

I've been running in two modes...one is around 20 LOP to cool it down to
around 385 CHT while the others run just slightly rich of peak. I can do
this without much effort, and under a wide range of throttle positions, and
density altitudes.

On a recent flight, though, I found #1 and #3 settling on temps that were
just too high to be happy with. I would go well ROP to get them cooled, but
burned a lot of fuel in the process and still had a warm 4th cylinder due
to the fact that it runs quite a bit leaner. This was all done at 75% power
or less, btw, density altitude was well above 11k (I was at 11k and it was
+10C)

Eventually, I tried something somewhat dramatic. I was determined to get
ALL the cylinders LOP. I leaned relatively rapidly and ignored the
disconcerting knocking/shuddering associated with the uneven amounts of
power being produced between the 4th cylinder and all the rest.

It all happened a bit quickly, but with cylinder 1-3 roughly 20-40 LOP and
#4 70-90 LOP, the CHTs dropped like a stone, seemingly in seconds, down to
380-385 across the board for #1-3 with #4 now in the 350-360 range. With
careful fiddling of the mixture, and countless experiments with throttle
position, I got the vibration down to the point where it was barely
noticeable. Eventually it just felt smooth...but I can't tell if I got used
to it, or things just settled down, although I wouldn't think it was
possible.

Final fuel flow was around 8.8-9.0 gph.

Finally, living the LOP dream with my O-360 :)

I tried repeating this later on, down low and wasn't able to repeat it (ie,
never got it smooth).

So, it's elusive, but possibly doable under just the right circumstances.
Since I do long trips on a regular basis, I'm definitely interested in
making this work.

Separately, I'll try to find out why it's running warmer in general. I did
have a mag replaced, the other rebuilt, and 4 new plugs installed in the
last year.

Honestly, I'm going to try to save some clams and get this converted to an
IO-360 (didn't realize it was relatively inexpensive until my mechanic
suggested it), get balanced injectors and run LOP as SOP. The difference in
cooling really is staggering. I know I'm probably preaching to the choir,
but I thought that O-360 owners might find it eye opening. Get up high and
give it a try if you have a 4 point engine monitor. You'll know it's
working when your leaning results in EGT and CHT's coming down :)

The trip, btw, was N07-KFTW-KSAV-N07, around 2600nm.

Keith

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<div dir=3D"ltr">Hey all,<div><br></div><div>I&#39;m waiting for winter to =
come around but it seems like my O-360 A1A has been running warmer than usu=
al, requiring me to power back very shortly after takeoff to avoid an excur=
sion north of 425 degree CHT&#39;s.</div>
<div><br></div><div>In any case, I know that LOP ops are hard to come by wi=
th an O-360 due to poor fuel distribution. Indeed, my #4 cylinder peaks wel=
l before the others, making it tricky to get them LOP.</div><div><br></div>
<div>I&#39;ve been running in two modes...one is around 20 LOP to cool it d=
own to around 385 CHT while the others run just slightly rich of peak. I ca=
n do this without much effort, and under a wide range of throttle positions=
, and density altitudes.</div>
<div><br></div><div>On a recent flight, though, I found #1 and #3 settling =
on temps that were just too high to be happy with. I would go well ROP to g=
et them cooled, but burned a lot of fuel in the process and still had a war=
m 4th cylinder due to the fact that it runs quite a bit leaner. This was al=
l done at 75% power or less, btw, density altitude was well above 11k (I wa=
s at 11k and it was +10C)</div>
<div><br></div><div>Eventually, I tried something somewhat dramatic. I was =
determined to get ALL the cylinders LOP. I leaned relatively rapidly and ig=
nored the disconcerting knocking/shuddering associated with the uneven amou=
nts of power being produced between the 4th cylinder and all the rest.</div=
>
<div><br></div><div>It all happened a bit quickly, but with cylinder 1-3 ro=
ughly 20-40 LOP and #4 70-90 LOP, the CHTs dropped like a stone, seemingly =
in seconds, down to 380-385 across the board for #1-3 with #4 now in the 35=
0-360 range. With careful fiddling of the mixture, and countless experiment=
s with throttle position, I got the vibration down to the point where it wa=
s barely noticeable. Eventually it just felt smooth...but I can&#39;t tell =
if I got used to it, or things just settled down, although I wouldn&#39;t t=
hink it was possible.</div>
<div><br></div><div>Final fuel flow was around 8.8-9.0 gph.</div><div><br><=
/div><div>Finally, living the LOP dream with my O-360 :)</div><div><br></di=
v><div>I tried repeating this later on, down low and wasn&#39;t able to rep=
eat it (ie, never got it smooth).</div>
<div><br></div><div>So, it&#39;s elusive, but possibly doable under just th=
e right circumstances. Since I do long trips on a regular basis, I&#39;m de=
finitely interested in making this work.</div><div><br></div><div>Separatel=
y, I&#39;ll try to find out why it&#39;s running warmer in general. I did h=
ave a mag replaced, the other rebuilt, and 4 new plugs installed in the las=
t year.</div>
<div><br></div><div>Honestly, I&#39;m going to try to save some clams and g=
et this converted to an IO-360 (didn&#39;t realize it was relatively inexpe=
nsive until my mechanic suggested it), get balanced injectors and run LOP a=
s SOP. The difference in cooling really is staggering. I know I&#39;m proba=
bly preaching to the choir, but I thought that O-360 owners might find it e=
ye opening. Get up high and give it a try if you have a 4 point engine moni=
tor. You&#39;ll know it&#39;s working when your leaning results in EGT and =
CHT&#39;s coming down :)</div>
<div><br></div><div>The trip, btw, was N07-KFTW-KSAV-N07, around 2600nm.</d=
iv><div><br></div><div>Keith</div></div>

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