The installing a Lycoming 0-320
engine to replace the stock Continental 0-200 engine is a
moderately popular conversion for Cessna 150 airplanes.
As in all engineering designs
there compromises must be made. When compared to a stock
150 the 150/150 has significantly enhanced performance
numbers but at the cost of additional weight and fuel burn.
As would be expected the addition
of an additional 50 horse power to a 100 horsepower airplane
produces some significant changes in performance. The most
notable performance change is in climb. The stock 150 is
not known for its’ ability to climb. A 50% power increase
completely changes the picture. The 150/150 will climb like
the proverbial homesick angle. The increase in cruise
performance while substantial is not nearly as spectacular
as the improvement in climb performance.
After all is said and done a
150/150 is sill a Cessna 150, with muscles. The weight and
balance restrictions and the V speeds are the same. No a
150/150 does not stall at a higher speed, it still has a
gross certified weight of 1600 pounds.
Would Anyone Want a 150 HP Cessna 150?
There are probably more reasons
for having a 150/150 than there are 150/150s. Just a few
reasons that come to mind are:
A 150/150 makes a fine banner tow
A 150/150 can be used to tow
A 150/150 is an excellent patrol
aircraft. It is as fast or faster than a 172, lower
operating cost and is more maneuverable.
A 150/150 is a great plane
for getting in and out of short strips.
A 150/150 is a hot rod. Not real
fast on the big end but quick to get started.
A 150/150 is much like a sports
car, nimble, quick on the controls with good performance.
A 150/150 is a good choice for
high elevation airport operations.
A 150/150 is just plane fun. (pun
If you think that you might like
to have a 150/150 but are not sure get a demo ride.
a 150/150 Perform?
The thing that a 150/150 does best
is CLIMB. The table below gives the climb performance of my
airplane equipped with a Sensenich 74”X53” climb prop. The
data was obtained by conducting three timed climbs to the
airplane’s service ceiling. The data from each climb test
were averaged and the results were linearized using the
least square fit method.
ALTITUDE IN FEET
RATE OF CLIMB IN
FEET PER MINUTE
ALTITUDE IN FEET
RATE OF CLIMB IN
FEET PER MINUTE
The prop makes a huge difference
in the climb performance. When the same series of flight
test were performed using a 56” pitch prop the climb rates
were 25% less than those with the 53” pitch prop.
Cruise performance is important to
all of us. If we wanted to go slow we would get a Cub. The
table below gives the cruise performance data at 75% power
for my plane, equipped with a “climb prop”. It is
interesting to note that there was little loss in cruise
speed at low altitude and a slight increase in cruise speed
at altitudes above 9000’ when the prop was re-pitched from
56” to 53”. This is most likely due to the fact that the
engine will turn faster at higher altitudes and allow more
power to be developed.
The cruise data is the result of
averaging the results of three timed five mile speed runs.
ALTITUDE IN FEET
CRUISE SPEED IN
MILES PER HOUR
ALTITUDE IN FEET
CRUISE SPEED IN
MILES PER HOUR
How Can One Get a
Purchasing a 150/150
There are two legal ways to get a
150/150, build one or buy one.
At any given time there are a
handful of converted 150s advertised for sale. The asking
price for 150/150s runs from a low of $18,000 to a high of
over $50,000. There are currently 150/150 listed for sale
on the Cessna 150-152 Club web site and in Trade-A-Plane.
When purchasing a 150/150 the same attention to the
condition of the airplane as with any other purchase is
necessary. In addition to the normal items to look for like
engine condition, corrosion, paint, interior, etc. it is
highly desirable to obtain ALL of the paper work pertaining
to the conversion, including the STC drawings.
When you purchase a 150/150 you
get a certified, flying airplane that you can fly right now
and upgrade, if required, on your time and fiscal schedule.
The other way to obtain a 150/150
is to do the modification yourself. This will entail at a
minimum buying an airframe, an engine, a prop, a spinner,
the STC, the installation kit, and numerous bits and pieces,
then locating a shop that is capable and willing to install
the conversion. Next comes the waiting and added expenses
while the shop makes the installation and finds all sorts of
little things what will need to be resolved, all taking time
and costing money.
There will also be additional
items that you will most likely like to add at the time of
the conversion. Since the 0-320 is thirstier than an 0-200
long range tanks while not an absolute necessity are a
convenient item if you plan to use the plane for cross
There are a couple of companies
that hold STCs for the 150 HP conversion. Or at least there
were two a few months ago. Aircraft Conversions
Technologies and Robert and Barbara Williams, DBA as Avcon
or Bush, both hold conversion STC. More about them later.
Obtaining the engine is not an
easy task. The STC calls for a Lycoming 0-320-E2D. While
these engines are by no means rare you can’t get one at the
7-11 store. The prices and conditions will vary greatly and
one will have to be very careful in order to obtain a good
value in a used engine. Of course you can always go with a
new engine. $$$ Ouch!
Then comes the prop and spinner.
A used prop will be very difficult to locate and a new one
will most likely be required. Again $$$ Ouch! The spinner
will be available from the 150 HP conversion STC holder but
most likely will not come with the kit.
When you get all of the big chunks
gathered up you can load it all in your little red wagon and
haul it out to your conversion shop. The STC holders will
give you an estimate of around 90 to 100 hours to make the
conversion. In my experience unless the shop that you are
using is well experienced in making the conversion these
numbers are way low. For your budget add 50% to 100% to the
STC holder’s estimated labor cost.
When the conversion is completed
carefully monitor the paper work and be sure that there are
337s for all of the major items.
Where Can I Get The Conversion
There are three sources for
STCs and conversion kits.
Aero Upgrade LLC
8252 Cessna Drive Medowlake
P O Box 25272
Colorado Springs, CO 80936
2121 Wildcat Way
Porterville, CA 93257
Talk to Harry Dellicker
Barbara and Bob Williams
Bush Conversions (Avcon
P O Box 431
Udall, KS 67146
The Williams are very nice people
and provide quality product with good documentation and are
very helpful. They are however a little slow to respond.
The last quote on delivery that I got from them was six
weeks. I honestly can not recommend their company
because of chronically slow service.
About Auxiliary Fuel Tanks?
For a plane that is going to be
used for cross country travel long range or auxiliary fuel
tanks are a very nice option. Running the 0-320 at 75%
power will consume 8.4 gallons per hour. With stock fuel
tanks you have 22.5 gallons of usable fuel. That translates
to about 2:40 to dry tanks. If you land with a VFR legal
thirty minutes of fuel remaining you will have an effective
range of around 275 miles in no wind conditions.
At Clinton there was a lot of
interest in and questions about my 150/150 and 150 HP
conversions in general. Since I have returned home I have
had a number of email inquiries about the conversion. The
following is an attempt to answer as many of those questions
as possible. I hope that Jeff and some of the other 150/150
drivers will chime in and flesh out the points that I miss
of correct me where I am wrong.
It should be noted that I have
only accumulated around 60 hours of flying in my little
airplane since I started flying it in March. I have learned
a lot but I still have a lot to learn. Steve can tell you
that I still can't spot land it worth a hoot, I smacked the
fantail of the mythical A/C
carrier at Clinton.
For me one of the most important
issues when considering an engine conversion is will the
resulting airplane fit my needs. I want an airplane that
will allow me to make cross country trips of 200 to 500
miles without the need to RON. Where I live it is necessary
to fly high to avoid getting beat up by turbulence in the
spring and summer. My home airport is 2800 MSL and our
second home airport is at 6800 MSL. I need to be able to
take off at gross weight when the DA is above 9000'.
Most important of all since I have
retired I need an airplane that will perform all of these
task at a relatively low capital cost and with a low
operating cost. For the last 25 years I have been flying
complex airplanes with big bore engines. The $3000 insurance
and $4000 annual
inspections/maintenance have priced those birds put of my
My decision to get into a 150/150
came after a couple of years of study and consideration.
A stock 150 just does not have the
power plant to meet my needs.
A 172 was my first choice but it
has very anemic performance at high altitude. I own half of
a Cherokee 140/150 with my son but again it does not climb
well or perform well at high altitude. (I flew a Cherokee
for over 1500 hours and an well acquainted with it's
capabilities and shortcomings.)
The 180 HP 177 is a little better performer than the 172 and
Cherokee but not a lot.
A 182 performs well at altitude
but the capital cost and operating cost are just too high
for my budget.
While the 150 is small in most
aspects it has essentially the same wing as the 172. When
the same engine is installed on a plane with 600 to 800
pounds of weight you get a plane that will CLIMB!
With insurance for a 150 at $500
per year and annual inspection cost at $500 per year. The
150/150 started to look good. Now add the fact that the
0-320 has a 2000 hr TOB and that a good overhaul can be had
for $10,000 as opposed to the 1200 hr TBO and $25,000
overhaul cost for a TSIO-520 and it looks even better. On my
normal trip of
200 nm the 150/150 burns 14
gallons of fuel as opposed to 22 gallons and the picture
becomes clear. Sure the trip will take an extra 25 minutes
but that is a small price to pay for the economic benefits.
What would I rather do with those 25 minutes than fly?
The decision was made. The 150/150
fit my mission profile to a tee and it is a plane that I can
afford to own and fly. I decided to do the conversion rather
than buy a converted airplane. I was really planning on a
180 HP 0-360 conversion. After I purchased my 1973L I found
what seemed like a very good deal on a 1968 H 150/150 so I
bought it too. We later found that the H model had BAD
corrosion in the right wing and the decision was made to
jack up the STC and drive the L model under it. I lovingly
call the result my Sport Hawk.
In addition to adding the 150 HP
engine there were a number of other mods added. Each of
these items was installed to fill a specific requirement.
The most often asked question is
"How do you like your 150/150". The answer to that question
is easy, I love it. It performs pretty much as I expected.
It will get off of the runway at 9000' DA in a reasonable
distance and climb out at around 700 FPM.
With the current prop (that is a
whole 'nother story) the Sport Hawk at rated gross weight
will climb from 3,500' to 17,000' DA in 26 minutes. While
not a blinding rate of climb it will get me up in to the
cool, smooth air in a reasonable time.
Cruise speeds at 75% power run
from 120 MPH TAS at 1500 feet to 137 MPH TAS at 12,500 feet
density altitude. At 75% power the 0-320 burns 8.4 GPH
(source Lycoming). Dropping the power to 65% reduces the
fuel flow rate to 7.3 GPH and will reduce the cruise speed
by around 5 MPH.
Pulling the black knob back to
50% drops the fuel flow to 6 GPH and farther reduces the
cruise speed by another 5 MPH. Note: 50% power for the 0-320
is equal to 75% power for the 0-200.
The next most often question is
"How much did it cost". I am not yet prepared to tell ANYONE
what the total package cost; I don't even want to know
myself. I will say that if you really
want or need a 150/150 you will be a LOT better off, both
economically and time wise, to sell your current plane and
buy a flying converted 150/150.
There is a lot of interest in the
Flint auxiliary fuel tanks.. To safely and conveniently fly
the trips that are normal for me more than 22.5 gallons of
fuel is needed. The Flint tanks, that add an additional 23
gallons of useful fuel and 35 pounds of empty weight.
They are installed in the outboard
portion of the wing. The last rib has a hole cut into it and
the tank slides into the wing. A fuel pump is installed
between each aux tank and main tank and when needed fuel is
pumped down from the aux to the main. I fly until I have
burned 12 gallons of fuel, then pump fuel from the aux tanks
until the fuel gages on the main tanks read full. When I
have burned 24 gallons I pump the fuel remaining in the aux
tanks into the mains.
The Flint tanks are well made, the
documentation is excellent and the support is outstanding.
However, the resulting fuel system is much more complicated
that is commensurate with a 150. If they can be found the
stock Cessna long range tanks (patroller tanks) even at only
40 gallons are a simpler and better choice.
DelAir holds an STC on converting
standard tanks from 22.5 to 40 gallons. I really
feel that this is a better solution. The installed
cost of the long range tanks are about the same as the
auxiliary tanks but maintain the simplicity of the original
Cessna 150 fuel system.
To assist in fuel management I
installed a JPI FS450 fuel flow computer. I have flown with a
fuel flow computer for many years and given the inaccuracy
of stock fuel gages it gives me a good deal of comfort to
have a cross check on my fuel burn. I have found the
readings of the flow computer agree within +/- 0.5 gallons
with the fuel truck meter.
Since there is no manual
information on power settings for the prop, engine, airframe
configuration I use the flow meter as my primary means of
adjusting power. The Lycoming owner manual provides a set of
curves for fuel flow at various power settings. 75% = 8.4GPH
65% = 7.3 GPH 55% = 6.2 GPH I don't pay much attention to
the Tachometer, I just let it run what it takes to get the
specified fuel flow. As I climb the tach reading heads on up
toward the red line. Talking to Jeff and Chris I find that I
burn more fuel than they do and that is due to the fact that
they don't flog their engines as hard as I do.
I installed a four point Alcor
EGT to assist in accurate leaning. I don't feel that the
cost and complexity of a four cylinder engine analyzer is
justified for the low compression, normally aspirated 0-320.
I lean to 50° rich of peak for best economy, per the
recommendations in the Lycoming owner's manual.
I found that the "lean until the engine runs rough the
enrich the mixture a bit works just a well as the EGT.
If you just have to have another gage in the panel make it a
four place CHT; if you take care of your cylinders they will
take care of you.
I installed a King KFC200, two Icom A200 com units, a Narco 122 nav radio
(VOR/ILS), a Sigtronics two place
intercom and rounded it out with a S-Tec Model 40 coupled
auto pilot. I kept the Narco AT 150 transponder that was in
the plane. My primary navigation chores are accomplished
using a Garmin CPSMap 295 GPS. I had the radio system and static
system tested and certified for IFR flight for those
occasions that it may be necessary to go IFR for safety.
It has long been my personal
policy not to fly single pilot IFR without at least a
minimal auto pilot. The S-Tech Model 40 coupled to the VOR
and a DG with heading bug serves nicely to assist in
maintaining heading during long trips or in IFR conditions.
It is also a big help on long trips.
All in all I am very pleased with
the package that I call the Sport Hawk. My trip to and from
Clinton last week was my first really long cross country
trip in the plane and I very pleased with the results. With
favorable winds a 1000 mile trip is easily accomplished in a
day, it took me 7:30 and one fuel stop to fly the 943 miles
to Clinton. When the winds are against me I think that 700
miles would be more comfortable, the return trip took 9:30
with two fuel stops and I was pretty tired when I got home.
Would I recommend a 150/150. I
surely would. The performance is pretty spectacular and it
is the most fun I have had flying in a long time. However,
if you are flying in low country and don't require strong
climb and high altitude performance a stock 150/152 is just
dandy and a lot cheaper.
As with most things in life the
150/150 entails some compromises. For strong climb and a
little increase in speed you must pay with flying a heavier
airplane; forget 1600 pounds and be prepared to take off and
fly most of the time at above certified gross weight. You
also pay in increased fuel consumption. Sure you can pull
back to 50% power and burn about the same rate as a stock
150 but I'll bet that you won't.
Would I build another 150/150? No
way. You can buy a flying airplane for a LOT less than you
will have tied up in converting your own plane. It took
nearly eight months and a bunch of buck to get the Sport
I hope that the foregoing answers
questions that you may have about 150/150 conversions.
Please bear in mind that these are my opinions and you may
get a completely different slant from some other 150/150