Late February of 2013. I took the
KR out for a nice warm up flight and was once again so pleased with the
way this plane flies, and the way this engine runs. I have a
number of updates I'd like to do to the plane, but just can't stand to
ground a plane that flies so nice. By afternoon, that tune had
I pulled the plane in to start on what should have been a quick and
easy annual inspection. First thing was to do a quick compression
differential check. Nearly perfect, 79/80, 78/80, 79/80, and
58/80. What? That can't be right! I checked a little
closer and the news was not good. It was leaking past the rings.
That does explain why the engine has been pushing a bit
more oil than expected. One of these tired old +.015
cylinders has finally given up. Surely it must be a broken ring.
I pulled the cylinder and saw nothing obviously wrong. But
measuring the cylinder, it has gone well beyond service limits and was
showing some cylinder wall distortion. It's time for new
So, I got in contact with my friends at Aircraft Specialties and
ordered a new set of Superior cylinders and a set of O-200-D
pistons (8.5:1 compression rather than the 7.0:1 compression in the
O-200-A). Wow! That was a surprise. I didn't think
Continental was going to make those pistons available. I got into
snag with the rings as Continental changed the top ring in the D
pistons, then made them pretty much unavailable. Finally resolved
it by having my friend Doug machine the top ring groove to fit the ring
set from the C-75 through O-200-A ring set.
Now that the plane is already down for major maintenance, it's time to
do all those little things I've been thinking about ever since the last
major refit in 2005.
May 8, 2013 - First ground run
on fresh top end and Pmags. My first
impression: The engine sure starts fast with
the Pmags. It also idles incredibly smooth. With the higher
compression pistons, I was really expecting the
idle to be a bit rougher. Instead, it idles as smooth as my
Honda. It's pretty clear that the Pmags must retard
the timing for idle. I shut off the power to the Pmags and found
they will self power down to 700 rpm. Below
700 rpm, the engine
just stops unless the Pmags are powered. Pretty much as
advertised. Log books are
completed and the
aircraft is now ready to fly.
June 23, 2013 - Flight
Testing report posted to the KRNet.
It's been a few weeks since I got my KR back into the air and got
started on Engine break-in and evaluating the changes in the
performance of the plane. I have roughly 10 hours on the new top
end now, so temps and performance are finally starting to settle in.
In February, as part of the annual I installed new Superior cylinders
on my O-200 with the 8.5:1 O-200-D pistons. I removed my Slick
magnetos and sold them, then replaced them with 2 new P-mags.
During break-in, I have been running the P-mags with the conservative
timing curve limiting the spark advance to 34 degrees. Now that
the engine temps have settled down, I'll be changing to the aggressive
timing curve that will allow the spark advance up to 39 degress. As of
this writing, I have not tried the aggressive timing curve yet.
Additionally, I cut down the exit area on the cowling and extended the
lower cowl back to match up with the front of the firewall. I
then added a servo actuated cowl flap. Other changes included
removal of the spring biasing elevator trim I installed several years
the addition of a servo actuated trim tab in the right elevator.
I added intersection fairings to the wheel pants to clean up the air
flow and cover the flat gussets on the landing gear that were still
sticking out in the
wind. I also corrected some wiring issues with the plane, built a
new instrument panel replaced the fuses with breakers, replaced all of
the switches, added a Dynon pocket panel and added all LED illumination
to light the panel better for night flight. I also pulled the
graphics off the plane, repainted some sections of the plane and am
waiting for delivery of new graphics with a new scheme for it.
All of this work is documented with lots of photos at
First flights: The first thing I discovered was that #2 CHT was
running pretty warm (420*F) and my oil temps were running much warmer
normal (215*F). Of course that was kind of expected since I was
in a new top end with new cylinders and we are into summer
weather. My experience with
overhauling cylinders is that a good quality hone job usually takes a
couple of hours for the temps to settle in. Same with chrome
cylinders. With new nitrided cylinders, I have 10 hours on it so
far, but the temps are still coming down a bit with every flight.
Right now under summer conditions, my oil temps are running at 205 -
210 (cruise with cowl flap closed). My hottest CHT runs at 390
during climb out, then settles
with all the CHTs even at 325*F in cruise.
I had pretty much convinced myself that I had somehow created a dog out
of my nice
flying KR while doing these "improvements". However, all of my
flying since completion has been in
hot, rough air with high density altitudes (10,000' DA on the
It's really difficult to establish any kind of usable numbers flying in
those conditions. I wasn't seeing any spectacular changes, but
instead was spending a lot of time managing temperatures during engine
break-in. I had pretty much convinced myself that this plane just
didn't fly like it did before tearing it apart.... in February.
Duh! It's just a bit warmer out now!.
Today I was able to spend some time in smooth air doing some one-on-one
flying vs a Cirrus SR-20. The reason that was important to me is
that the performance numbers for the Cirrus are well established and
Cirrus flies the book numbers very nicely. Additionally,
this Cirrus is owned by a friend, so he and I have many, many
flying side-by-side and racing each other. I have always been
able to smoke the Cirrus in a big way in climb performance, but once we
reached altitude, he would gradually creep up on me and walk away at
about 2 - 3 knots faster than my KR. If we were going to fly
together, I always needed for him to reduce throttle just a
little for me to stay with him. Today's comparison was an eye
opener. As usual, I
let him take off first, and went smoking by during climb out.
Then I throttled back enroute to our destination cruising at
10,500'. After 30 minutes, I finally turned a wide 360 to let him
catch up. I then dropped into formation with him, throttle up and
passed him. Ok, well, I had just descended from above him, so I
throttled back and let him pass me at the same altitude, then throttled
back up and passed him again, with the KR steadily moving away at 1 - 2
knots faster than the Cirrus. The Cirrus has well established
numbers showing that it flies at 155 kts under those conditions.
My conclusion is that at full throttle level flight, my KR now tops out
at roughly 156+ kts, which is right at 180 mph. My normal cruise
is more in the range of 140 kts (160 mph). My goal when I started
on these mods was to reach 155 kts at full throttle level flight.
I really thought I had failed as previous flights had only shown a top
speed of 151 kts. However, I had only got one other chance to
actually run the plane in smooth air while the engine was still very
in the break-in at that time. But from today's flight I found
that I was indeed successful at reaching my quest for speed.
My impression of the P-mag performance: So far, I haven't seen
anything great in the way of performance or fuel savings flying the
Pmags. However, a caveat to that is that I have always ran my
mags at 30*BTDC (since I am always at high altitudes) and my Pmags are
currently limited to 34*BTDC, so I shouldn't expect to see anything
special until I put in the more aggressive timing curve. However,
I have noted that the P-mags significantly retard the timing for start
up and idle, which makes for a much smoother idle. Additionally,
the Pmags have a much hotter spark which will light less than ideal
mixtures that weren't firing reliably with the magnetos. This
makes for an instant startup whether hot or cold. Additionally,
it seems to have resolved the following problem. Ever since I
built the 4 tuned length header pipe exhaust system, my engine has
always loved to
run at full throttle. It ran very smooth at full throttle.
However, when I would start dialing back the throttle, the engine
would get decidedly unhappy. It just didn't run smoothly until I
reduced the throttle by 2 inches of manifold pressure. I
had concluded that the carb was simply going too lean under those
conditions thanks to the header pipes creating better flow with the
valve overlap. So I had to either run WOT or do more of an
economy cruise. In between I had to enrichen the mixture and the
engine was still not running smooth like it did before the new exhaust,
but was acceptable. With the installation of the Pmags,
the roughness simply went away. The engine still loves to run at
WOT in level flight, but now any other throttle setting works equally
as well. The CHTs definitely run a bit warmer with the additional
advance, but the EGTs now run significantly cooler. EGT on #2
cylinder now runs 300 degrees cooler than it did previously, although
the CHT on #2 is now bumping up against 400*F during climb out.
This is an indication that a lot more of the fuel is burning in the
cylinder and not burning in the exhaust. The cooler EGTs should
also contribute to longer exhaust valve and exhaust valve guide life.
I haven't reached a conclusion about whether adding the cowl flap was
worth the effort of not. One issue is that the cowl flap servo
really disturbs or partially blocks the air at the bottom of the oil
tank. That may be contributing to the warmer oil temps.
While the oil temp is running about 10 degrees warmer than I
would like, it always stay in the green and has gone no higher than
215*F. Opening the cowl flap drops the oil temp roughly 10* and
does about the same for the CHTs. I wonder if I had just left the
cowl flap fixed in the streamline position and not had the servo in the
cowl disturbing the air if I wouldn't have been just as well off.
One advantage to the cowl flap is that I also have it set up so I
can pull the cowl flap up into a negative position and completely close
off the air flow from the center of the cowl. That may help bring
the oil temps up to a more acceptable temperature during the winter
months. I won't be able to test that experiment for several
months yet. :o) When the cowl flap is open, it actually does act
like a flap under the nose of the plane. It lifts the nose
substantially and generates a lot of drag. The plane accelerates
significantly and requires a substantial nose up bump on the elevator
trim when I close the flap.
The new trim tab on the tail works nearly perfectly. When I had
the old tail on the KR with a trim tab, it seemed to take a significant
amount of trim. With the larger tail with the 0009 airfoil, the
trailing edge of the trim tab doesn't move more than 1/2 " while
trimming between high WOT cruise and 80 mph IAS approach speed. I
built the trim servo with a huge amount of trim available to it, so the
trim is a little bit touchy, and took a little getting used to after
flying the spring biasing trim that hardly worked at all. It
would be nice to have it a bit less touchy as the whole speed range of
the plane only moves one LED on the indicator. However, it is
nice to have sufficient trim for the plane to fly hands off at any
Intersection Fairings on Wheel Fairings: While I have always been
concerned about the flat plate gussets on the Diehl wheels sticking out
of my wheel pants, it would appear that dressing them up with
intersection fairings did more for the looks of the plane than the
performance. However, since I did that at the same time that I
modified the lower cowling, I can't truthfully credit one modification
over the other for the incremental gain in performance. I am very
pleased with the finished look of the wheel fairings sporting the
intersection fairings, but I can't truthfully say they either did or
didn't improve the performance of the plane. But I guess it
couldn't have hurt to cover those gusset plates.
I will do another round of evaluations once I put the aggressive timing
curve in the P-mags and will report back if I find anything
July 1, 2013 - P-Mag timing.
I dialed in the aggressive timing on the P-mags for testing this
weekend. I really don't expect better performance from the
additional timing advance. It should have a some additional
timing advance with lower manifold pressures at higher altitudes or
partial throttle operations (cruise flight) to help with fuel
savings. Bear in mind that I operate from a high altitude
airport, so can not pull more than 23.5 inches of MP, so expect some
timing advance even during full throttle climb operations. I
found that during climb out, my hottest CHT bumped up from 390 to
405. That is still acceptable, although on the cusp of what I am
comfortable with running. As soon as I start dialing the throttle
back a little, the CHT immediately drops as the throttle plate disturbs
the air flow and the fuel mixes and distributes a bit better across the
intake spider. #2 cyl has always been the hottest CHT under full
throttle conditions due to an uneven fuel distribution at full
throttle, so has become my measuring stick during climb
operations. As soon as the throttle is reduced, the temperature
drops into line with the other cylinders. During today's flight,
under cruise conditions the CHTs ranged from 300 - 340*F across all 4,
with only #2 (back left) running a bit warm during climb out.
The biggest issue was the oil temp during cruise flight. I was
cruising with the cowl flap closed and 18.5" MP at 11,500'. Under
those conditions, the timing curve should be fully advanced to
39*. My oil temp topped out at 220*F and stayed there under those
(summertime) conditions. I was able to drop the oil temp back to
210* by opening the cowl flap, but that also induces a significant
amount of drag, which is less than ideal for cruise flight. This
is about 15 degrees warmer than the oil temp was running with the
timing curve topped out at 34* under similar conditions. I am
going to leave the timing dialed up while I explore ways to get a bit
more cooling air directed at the oil tank (the O-200 does not have an
oil cooler). If I can't get a little better results with the oil
temps, I may have to restrict my timing advance to 34* during the
summer months and dial up the timing for the fall and winter months.
July 5, 2013 - P-Mag timing.
I tested with a 2" scat intake pointed at the oil tank to help cool it.
That made a 2* difference in the oil temp. Dropped it from
220 to 218, which I consider to be insignificant. However, I also
discovered that the oil temp seems to stabilize at 220 in cruise and
stays there, so while it's a bit warmer than I would like, it's not a
major concern. I decided to move the scat hose back to the heat
exchanger for the cabin heat and not bother with it on the oil tank.
I'm not interested in adding the weight of an oil cooler to the
plane and it's really not a necessity. My long term solution is
going to be to pull wires back from the Pmags to a toggle switch in the
cockpit allowing me to select either conservative or aggressive timing
before startup. With the conservative timing curve in, my oil
temp tops out at 208 in cruise under summertime conditions. With
the aggressive timing curve, it tops out at 220. So, I'll likely
select the conservative timing curve (limited to 34* advance) for
summertime operations, then select the aggressive timing curve (limited
to 39* advance) for all other conditions. Max performance under both
timing curves is the same. The difference is that the additional
timing advance will allow a bit more fuel savings at lower cruise
July 12, 2013 - P-Mag discussion from
I would think that the increase in oil temp would be directly
proportional to the increase in CHT since it is the more complete
burning of the fuel in the cylinder that causes a temperature increase.
Therefore I would be more inclined to do something to increase
the cylinder cooling with the baffles, air inlets and outlets from the
cowl, etc. than to try to directly cool the oil. Even if your
CHTs are not overly hot the cylinders are obviously getting hot enough
for long enough to increase the oil temp.
Actually, at BDC on each stroke, the oil port in the rods squirt oil
against the bottom of the piston head of the opposing cylinder to cool
the pistons. That's the genesis of the higher oil temperature.
Additional burn time in the cylinder equals higher piston head
temps, which gets absorbed 100% by the oil. The CHTs do go up a
small amount with the advance in timing, but my CHTs are well under
control with all of them running in the 300 - 340 range.
While I have no doubt they would make a difference, I'm not really
interested in adding heat sinks or an oil cooler to the engine.
220*F is still in the green and that is as high as it goes under
summertime conditions. There is really no drop off in performance
for selecting the more conservative timing curve, so I really don't see
any down side to adding a switch to simply select the more conservative
timing curve on a hot summer day, then the more aggressive curve any
other time. That's why they put the multiple timing curve option
in the Pmags.
Something that's probably worth pointing out here is that the way the
Pmags operate causes the temps to run differently at different times
from what you have learned to expect while using magnetos with fixed
timing. For instance, with magnetos, my oil temps would always
peak during a long climb, then cool back down a bit once I throttled
back to cruise. That is not the way it works with the Pmags.
My oil temps are pretty much the same as I have always seen
during take off and climb conditions. Once I settle in at cruise,
the oil temp climbs a bit until it reaches it's peak temperature, then
stays there. The reason for that is the timing curve.
During full throttle and climb operations, the timing runs a bit
more conservatively to give a significant margin to prevent detonation,
which causes less burn time in the cylinders. Under worst case
conditions (low altitude, full throttle), the ignition timing will be
the same as you would see with the fixed timing on a magneto.
It's when you get to altitude and start pulling the throttle back
that the timing goes to full advance, which causes a significantly
longer burn time (14 degrees longer burn) in the cylinders. That
additional burn time is creating more heat in the piston itself and
that is what is driving the oil temp higher than what it used to run.
The actual power output isn't any higher, so the CHTs are not
significantly higher than they were before. But the oil cooling
the bottom of the piston heads has to absorb a lot more heat, and it
shows up as higher oil temps. This probably wouldn't be seen at
all in an engine with an adequate oil cooler, but shows up in the O-200
due to the lack of any kind of oil cooler. As another side note,
the additional burn time in the cylinder means there is less fuel
burning in the exhaust. All of my EGTs have dropped between 200
and 300 degrees from where they used to run. The good news there
is that the exhaust valve and exhaust valve guide life should be
significantly longer as the exhaust valves are seeing less heat than
they were before.
> You wrote: << However, the additional timing advance will
allow you to save fuel by burning more of it in the cylinders and less
of it in the exhaust, especially if you fly throttled back or at high
> Your post begs the question: How does it know we "fly throttled
back or at high altitudes"? What additional data besides ignition
trigger does the P-mag have to decide to advance the ignition?
Emag/Pmag uses manifold pressure and RPM to determine the spark advance
depending on which ignition profile is selected. Manifold
pressure tells it how much you are asking of the engine, so when you
throttle back or are at high altitudes, the manifold pressure is way
down and the ignition will advance. Using the aggressive profile,
2500 rpm and 30" MAP and the ignition will be at 25* BTDC. 2500
rpm and 19" MAP and the ignition will be at 39* BTDC. Everything
else is going to be somewhere in between as determined by the timing
curve profile. I should also note that the ignition retards back
to 0* for startup and is retarded for idle. Makes the O-200 idle
like my Honda. :o)
Los Alamos, NM
September 5, 2013 - P-Mag
This last month I added a single throw double row toggle switch to the
panel and pulled the P-Mag timing jumper wires back to it. With
the switch in the up position (open) at power up, the aggressive timing
curve (39* max advance) is selected. With the switch in the down
position (closed) at power up, the P-mags will load the conservative
timing curve (34* max advance). Unfortunately, for the most part
I have still been dealing with summer time temperatures. With the
hot outside air temps, my oil temp with the aggressive advance
typically runs at 215 - 220 in cruise with the cowl flap closed.
With the conservative timing advance selected, the oil temps have
been typically running at 205 - 210. I got in one flight in
cooler air under a cloud cover with some light rain and found that with
the conservative timing, my oil temp dropped to 195. While I
concern myself with the oil temps as they are warmer than what I am
used to seeing, it should be noted that they are all still well within
the normal green limits and there is no tendency for the oil temps to
want to drive any higher. My expectation is that I am likely to
run the conservative timing during the summer months, then switch to
the aggressive ignition timing the rest of the year. I plan to
fly the KR to Mt Vernon, IL to the KR Gathering in early October.
I am really looking forward to the KR Gathering as this will be
my first opportunity to test the P-mag ignition system below 8500'.
My cowl flap seems to make roughly 10 degree temperature difference in
the oil temp between having the flap open and cruising with it closed
to the streamlined position. When I built the cowl flap, I also
added a third position to the flap that allows me to retract it up to
meet the bottom of the firewall and effectively cut off nearly all air
flow around the center of the engine. I look forward to
additional testing this coming winter as this engine has traditionally
run quite cold oil temps during the winter months. With a cowl
flap that can close off the center of the cowl and the aggressive
timing profile which clearly creates significantly more heat loading
for the oil, I am hoping this engine will be capable of sustaining warm
enough oil temps during the winter months to keep the water cooked out
of the oil.
was asked to report back on my experience with the Emag/Pmag
set up. My overall impression is that I like them. But
don't buy them thinking it's going to improve your performance.
It's not likely to make a big impact. However, the
additional timing advance will allow you to save fuel by burning more
of it in the cylinders and less of it in the exhaust, especially if you
fly throttled back or at high altitudes. The other benefit I see is
with the much hotter spark supplied by the electronic ignition and
automotive style plugs. The engine simply runs better and will
fire marginal mixtures that a magneto won't fire. With the
current high cost of magnetos, the cost to buy a set of Pmags is only
marginally more and will pay for itself over time. So I recommend
them as a buy.
Los Alamos, NM
October 21, 2013 - Fall weather
and low altitude testing
Early October I finally got to take this plane on a long enough cross
country to actually learn something more about the overall performance.
I flew the plane from New Mexico, to northern Arkansas, to
Tennessee, to southern Illinois, and back to New Mexico. This is
the first opportunity I have had to get the plane below 8500' for
First off, when I built the cowl flap, I made it essentially a three
position flap. I can fly with it open, in the streamlined
position, or in the closed position, which actually pulls the cowl flap
up inside the back of the cowling to shut off much of the air flow
around the oil tank. This allows me to keep a better handle on
the oil temperature for testing with the Emags. The bonus I found
was that while I can see a huge difference in the speed and performance
of the plane between running the cowl flap in the open position vs the
streamlined position (flush with the bottom of the cowl), I was
pleasantly surprised to find that the plane was even faster if I could
run with the cowl flap in the fully closed position with the flap
pulled up inside the cowl.
I found that while I have been concerned about high oil temps, the oil
temps in the summer time do run a bit warm, but never approach red
line. In fact, the highest I saw during the 6 months of testing
was 220 degrees with the aggressive timing selected and cruising at
11,500' on a warm summer day. For summer time ops with my O-200
that uses no oil cooler, I need to run the more conservative timing
curve during summer time operations when flying at altitudes above
6500'. By running the more conservative timing curve, I can
completely close my cowl flap for cruise flight and my oil temps tend
to top out at roughly 215 degrees, then will slowly cool back down to
205 during a long flight. Any time I am below 6500', or not in
the heat of summer, I can run the aggressive timing curve at any time
with no concern about oil temps. At lower altitudes, the engine
temps are not significantly warmer than they were when I was running
While at the KR Gathering in October, I had a generator failure.
In order to gain better access to change the generator, I removed
the left E-mag. The owner of the FBO and one of the other KR
builders was there when I mounted the Emag back in place and set the
timing. I think both were taken aback at how quick and simple it
was to set the timing and have the engine ready to run.
Financially, it probably didn't make sense for me to remove a perfectly
good set of magnetos and replace them with a pair of P-mags.
While I estimate that I am burning something slightly less than
1/2 gallon per hour less fuel than previously, it would take a lot of
flying to make up for the $3000 price tag to install a pair of P-mags.
On the other hand, if one needed new magnetos, the cost of new
mags, harnesses and plugs is pretty close to the cost of a pair of
P-mags. So why not take advantage of the variable timing, the
easier maintenance, and using the much less expensive automotive spark
plugs? There is no question that the engine runs smoother with
the electronic ignition and hotter spark. The Emags will light
fuel mixtures that just won't fire with a magneto, so the engine starts
easier and runs better.
I made numerous changes to my plane at the same time that I installed
the P-mags. I changed from 7.0:1 pistons and tired cylinders to
8.5:1 pistons and new cylinders. I also did some aerodynamic
clean up with intersection fairings on the wheel pants and some
streamlining and a cowl flap were added to the lower cowling.
What I can say is that the plane is noticeably faster at lower
altitudes. At higher altitudes in the thin air, it was more
difficult to discern the changes in performance, but after learning a
bit more about how the plane likes to be operated at low altitudes this
fall, I found the same operating principles apply at higher
altitudes. No question that it performs better. But like so
many homebuilders, the changes to the plane are a concatenation of
numerous changes, rather than one little thing I can pinpoint.
Over the past 16 years and 1000 hours of flight time in this aircraft,
I have made many, many changes, mostly targeting either horsepower,
handling characteristics, or aerodynamic clean up. No one thing
was a huge hitter on the speed chart, but all the things I have done
over the years have added a solid 35+ mph to the full throttle speed of
this aircraft. On the down side, they have also added nearly 100#
to the weight of this aircraft as compared to what it weighed 16 years
January 15, 2014 - additional
Someone emailed me asking what kind of speeds I see out of this plane.
I was going to write back referencing this web page. Then I
read it and found that while I put lots of probably meaningless
information on here about oil temps, CHTs, and EGTs, I neglected to put
out any kind of speed numbers. Up until my October trip, the lack
of speed information was intentional as I rarely ever get to do any
testing below 8500'. My plane simply does not perform at it's
best at 8500 and up, which is where I do nearly all my flying. So
what did I find while flying down low? During my October trip, I
found that at 4000'MSL and below at gross weight, my KR cranked along
at a solid 158 kts (182 mph) with the engine turning 2800 rpm,
which is about 50 rpm over red line. But
that is full throttle cruise, not a normal cruise. I
had to be very careful during descents to avoid overspeeding the
airframes VNE of 170 kts (195 mph). A more reasonable cruise was
at 140 - 145 kts. At higher altitudes where I normally have to
fly (in northern NM), I usually flight plan for 140 kts and that seems
to work out pretty good for a normal cruise. I can't keep up with
the RV crowd, but this plane was never intended to do that. But
for an fast economical plane, it does it's job exceptionally well.
June 22, 2014 - Update on
During the annual inspection in May, I noted an area allowing a
significant leak past the baffling in front of the left front (#4)
cylinder. I made some additional modifications to the baffling to
close off the leak and move more air past the front cylinder to
the back. Upon testing, this has made a significant difference in
the cooling to the hottest cylinder (#2 at the back left). I can
now run the full 39° aggressive advance on the Emags with #2
cylinder now topping out at 400°F with the cowl flap half closed to
the streamlined position during climb and all 4 cylinders running even
at 300°F in cruise with the cowl flap fully closed. It would
appear the cooling issues I have battled with for the last year were
resolved by improving the baffling.
September 2015 - Update on cooling and Emags.
In August I finally noticed 2 spark plug leads laying across a critical
opening for cooling on top of #2 cylinder. Hey, it's only taken
me 18 years to notice this. I mounted those wires to the side of
the cooling baffling to get them out of the way and dropped the #2 CHT
by >50 degrees. Now my max CHT during climb is typically
350° and settles back to 300° at cruise.
In September I flew the plane to McMinnville, OR to attend the KR
Gathering. Including my time horsing around burning lots of fuel
at low altitude at the gathering, my fuel burn for the trip averaged
5.4 gph over 17 hrs. Cruise altitude going out varied, but most
was at 10,500', and some at 8500', then an 11,500' climb over the
weather to cross the Cascades. The return trip home was all flown
at 11,500' with the exception of a 13,500' climb over the weather to
cross the Cascades again. On a hot day, oil temps typically top
out at 215 - 220° during climb, then drop back down to 195 -
200° in cruise. During winter, oil temps usuallly Still run
up to 200°, then drop back to 180° during cruise. I don't
think I could ask for better numbers from an engine with no oil cooler
and no vernatherm to help control the temps.
Feel free to email me with comments or questions at
Stay tuned. More to come...