Murphy Aircraft
can help with your M14 Purchase!
The ultimate radial powerplant for your Murphy Aircraft is alive and kicking. Need more information? Check out the rest of this page
or Contact Us with your request.
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M14 Radial Engine Sources
Do you know of another source for the M14? Please contact us.
We have access to propellers, M14 engines and several parts available for purchase, for example:
Props are available for as low as $4500.0USD plus shipping and packing fees.
New old stock M-14Ps for $22,500.00USD. All of these engines are checked by a factory overhaul facility.
We also have available to us, several M-14Ps with very low total time for $12,000.00USD to $16,000.00USD while supplies last.
All engines are Series II and have high capacity cooling heads.
Here is a list of components that we can get for you.
- Shower of sparks
- Fuel systems with boost pump, check valves, ready to install fab for your configuration
- Composite air cylinders
- Stock round air tanks
- Oil coolers
- Air systems
- Starter sytems for air start
- Conversion fittings
- Mags
- Carbs
- Oil pumps
- Fuel pumps
- Air compressors
- Fuel psi spheres
- Cylinders
- Piston and ring sets
- Rods
- Prop gov arms (factory units that don't elongate like the cheap aluminum wheels)
- Prop gov limit stop brackets
- Carb heat boxes
- Engine mount rings
- Exhaust systems
- Tachs and tach generators
Culp Specialities can fabricate components for the M-14 installation and will provide quotes and time frame.
M-14P General & Technical Information
Front Back
Tthe following links have been collected for your research and
information on the engine.
With over
1000 hours on the radial installation now, the Murphy
pilots are getting very accustomed to "radial etiquette". But
they have fallen in love with the power of the radial and its
take-off and climb performance. Burying the VSI at 2,000 fpm
is easy to attain at 80 knots!
Please Note * Murphy
Aircraft does not endorse or support any of these sites,
they are for information purposes only and all facts or
statements should be confirmed as being valid
M14P Basic Specifications |
| Designation - |
M-14P |
| Cooling System - |
Air |
| Number of cylinders - |
9, radial, in one row. |
| Dry mass of basic engine, no accessories, no oil, no mount ring - |
214 kg or 471 pounds. |
| Cylinder order - |
Counterclockwise from rear view, #1 at top |
| Compression Ratio - |
6.3 |
| Displacement - |
620 Cubic Inches / 10161 cc |
| Rotation, viewed from rear - crank & prop. - |
Left hand. |
| Propeller reduction gear - |
Planetary gears. |
| Propeller reduction ratio - |
.658 |
| Supercharger - |
Centrifugal, single stage, mechanical drive. |
| Supercharger gear ratio - |
8.16 |
| Carburetor - |
Pressure type. |
| Start System - |
Compressed air. |
| Magneto - |
M-9 |
| Max magneto check RPM drop (crankshaft) - |
85 RPM (at nominal or first cruise pwr setting) |
| Compressor - |
AK -50A |
| Oil pump - |
Gear, with pressure and scavenger sections. |
Pressure and Temperature Limits |
| Fuel pressure limits |
2.8 to 7.1 PSI, Min. idle 2.1 PSI |
| Oil pressure, measured at oil pump fitting - |
57 to 85 PSI, Min. idle 14 PSI |
| Oil temp, minimum at engine inlet - |
40 C. |
| Oil temp, recommended at inlet - |
50 to 65 C. |
| Oil temp, max inlet for normal operations - |
75 C. |
| Oil temp, max inlet no more than 15 minutes - |
85 C. |
| Oil temp, maximum at engine outlet - |
125 C. |
| Oil temp, max diff between inlet & outlet - |
50 C. |
| CHT, (#2 & #6 cylinder) Recommended - |
140 to 190 C. |
| CHT, minimum for normal ops. - |
120 C. |
| CHT, min for normal prolonged ops. - |
140 C. |
| CHT, maximum for prolonged ops. - |
220 C. (max continuous CHT) |
| CHT, max for 15 minutes at TO & Climb pwr. - |
240 C. (permissible during takeoff and climb) |
Please Note : These numbers are for reference only. Consult your engine operation and maintenance manual for the correct parameters for your engine. |
M14P Power Chart
Power chart from the M14P manual. RPM is for the crankshaft not the propeller (multiply crank RPM by .658 to get prop RPM). Note that these are the sea level, standard day, settings.
Rating |
HP |
RPM |
% |
Fuel Consumption
Grams/HP/Hour |
Fuel Consumption
Gallons/Liters per hr. |
Blower Outlet Pressure (mmHg) |
Take Off |
360 |
2900 |
99% |
285-315 |
37.7- 41.7 Gal
141.7 - 157.9 Liters |
125 - 15 (surplus)
885 - 870 mmHg or 34.8 - 34.2" Hg |
Nominal 1 |
290 |
2400 |
82% |
280-310 |
29.8 - 33.0 Gal
112.8 - 124.9 Liters |
95 -15 (surplus)
855 - 840 mmHg or 33.6 - 33.0" Hg |
Nominal 2 |
240 |
2050 |
70% |
265-300 |
23.4 - 26.5 Gal
88.6 - 100.3 |
75 -15 (surplus)
835 - 820 mmHg or 32.8 - 32.2" Hg |
Cruise 1 |
.75 of N2 |
1860 |
64% |
210-230 |
13.9 - 15.2 Gal
52.6 - 57.6 Liters |
735 mmHg +/-15 28.9" Hg (absolute) |
Cruise 2 |
.6 of N2 |
1730 |
59% |
215-235 |
11.4 - 12.4 Gal
43.2 - 46.9 Liters |
670 mmHg +/-15 26.4" Hg (absolute) |
To convert grams per horsepower/hour, first convert grams to pounds/HP (1 gram = .0022046 pounds).
Thus 285 grams * .0022046 = .628311 pounds * 360HP = 226.2 pounds/hour / 6 pounds per gallon = 37.7 gallons per hour. 315 grams * .0022046 = .694449 pounds * 360HP = 250.0 pounds/hour /6 pounds per gallon = 41.7 gallons per hour.
The Blower Outlet Pressure (boost) is always confusing. What they mean by "surplus" is that pressure OVER standard atmospheric pressure, which at sea level on a standard day is 760 mmHg (29.92" of Hg). So add 125 mm (the max SURPLUS) to the 760 = 885 mmHG. The minus 15 would be 870 mmHg. Therefore the manifold pressure at max takeoff power or 2900 RPM will be between 885 and 870 mmHg or 34.8 to 34.2 " Hg as read on your manifold pressure gauge on a standard day at sea level.
Thus the Blower (boost) increases the manifold pressure over standard atmospheric pressure at this power setting approximately 5 inches of Hg.
At the Cruise 1 power setting is where you can expect to achieve your best speed and fuel economy. The ".75 of Nominal 2 (240 HP)" = 180 HP at 64% RPM. Fuel consumption at this rating is 210 to 230 grams/hp/hour or 13.88 to 15.21 GPH. That's with a manifold pressure setting of 735 +/- 15 mmHg or 28.35 to 29.52 inches of Hg. So, as a veteran WWII B17 Bomber pilot told me a long time ago, to get the best cruise speed with the best fuel economy, run the engine "oversquare" or make the engine turn the prop and not the prop turn the engine. ie: Lower rpm (in this case 64% or 1860) and higher manifold pressure (28.35 to 29.52 "Hg). In cruise flight, try setting the power to 65% (1880 - 1900 RPM) and 29 "Hg.
M-14P Carburetor Jet Mod (PDF)
Manifold Drain (PDF)
Fred's Article Regarding Operations of the M-14P Radial
