The UL390iSA is basically an UL390iS engine.

A modified engine casing, oil sump and oil pick up system, designed by our very own ULPower team, and an additional inverted oil system allows the ULPower engines to fly inverted:

This inverted oil system copes with potential greasing issues. The oil pick-up tube in the oil sump is mounted with a hinge joint. While climbing or diving up to an angle of 90°, the oil pump can pick up the oil from the sump without any problem.
The oil inverted valve can change the pick-up direction while climbing or inverted flying, this means that the oil is coming from the top of the engine casing (which is now the lowest point). The large (but light) “oil air breather” prevents the oil from leaving the engine.

The fuel injection system (instead of carburetor) prevents the engine from stopping or losing fuel when flying inverted.
IMPORTANT REMARK: modification in your fuel tank is needed to prevent engine from sucking air.

Thanks to our electronic RPM limiter, ULPower engines can fly inverted for hours and hours without danger of over-running.

Oil capacity: Oil sump must be filled with at least 4 liter oil. (0.US gal)



  • 4 stroke, 6 cylinder, horizontally opposed
  • Dual (redundant) electronic spark ignition (variable timing)
  • Electronic multipoint fuel injection (pressure and temperature compensated)
  • Electronic RPM limiter
  • Direct propeller drive
  • 7 bearing crankshaft with surface hardening treatment and additional large thrust bearing (ball bearing type)
  • Single central camshaft
  • Push rods, tappets and OHV (hydraulic compensators have not been used)
  • Wet sump forced lubrication with integrated pressure regulator
  • Ram air cooled cylinders and cylinder heads
  • Integrated permanent magnet AC generator, external rectifier-regulator
  • Electric starter
  • Electric fuel pump and pressure regulator to eliminate vapor lock and facilitate starting even under adverse conditions
Displacement 3900 cc
Bore 105.6 mm
Stroke 74 mm
Compression Ratio 9.1 : 1
Firing Order 1 – 4 – 5 – 2 -3 – 6
Direction of Rotation Clockwise – Pilot’s view
Maximum Torque
(ISA conditions)
370 Nm @ 2800 rpm
Power rating
(ISA conditions)
160 hp @ 3300 rpm / 145 hp @ 2800 rpm
Installed weight Basic standard engine weight:100 kg (including starter motor and alternator)
DC output 50 A
Oil capacity 4 L
Fuel MOGAS with min. 98 octane rating or AVGAS (98 Oct = 90MON = 94 AKI)




Power / Torque curve

The power and torque curve of the engine has been established by repeated dyno tests, which were performed at sea level and in weather conditions close to the ISA standard. The following graph shows the real, available power and torque coming from the crankshaft of the UL390iSA engine corrected to the International Standard Atmosphere conditions at sea level.

Power vs Density Altitude

The following graph shows the calculated available power of the UL390iSA engine at different RPM settings, WOT (wide open throttle) and varying density altitude.

Power vs MAP

For more information on ISA, density altitude, interpretation of this graph, the conversion of the figures to actual atmospheric conditions, refer to the “Engine Resources” section on our website and more specifically: “ISA conditions & conversion”.




Dimension Weight
Maximum dimension in X direction (length)* 723 mm [28.4 inch]
Maximum dimension in Y direction (width)* 654 mm [28.97 inch]
Maximum dimension in Z direction (height)* 472 mm [18.58 inch]


  • Dry weight of the basic standard engine from serial production: 85,3 kg (188 lb)
  • Ready-to–fly weight: 103.8 kg (228.8 lb)

For more details please check the installation manual.




Fuel consumption (Liter/hour)

Specific fuel consumption

These are values at full throttle. When cruising estimated average is UL390 ±21l.
(depending on type of plane, personal style of flying, cruise speed , climate circumstances)




The following is a list of the ULPower engine standard design features, all included at no additional cost.

  • Dual (redundant) electronic spark ignition (variable timing)
  • Multi-point electronic fuel injection with automatic altitude and temperature compensation
  • Electronic RPM limiter
  • Rubber mounts
  • Alu ram airboxes
  • Breather with Oil/Air separator (including: temperature resistant hoses and banjo connections)
  • Direct propeller drive
  • Wet sump forced lubrication with integrated pressure regulator
  • Stainless steel exhaust and muffler included
  • One electric fuel pump, two fuel filters, fuel pressure regulator and air filter

Extra options

  • EGT Sensor kit
  • CHT Sensor kit
  • Fuel connection kit
  • Oil Cooler kit
  • Double ecu
  • Different types of prop flanges
  • Different exhaust systems
  • Swiveling oil pick-up tube
  • Dual alternator
  • Forced air cooling

Please contact us for more info / prices








Front 3/4 – 2.55 MB

Front 3/4 top – 2.7 MB

Back – 2 MB

Back top – 2.07 MB

Front – 2.55 MB

Front top – 2.14 MB

Left side – 1.76 MB

Right side – 1.93 MB

Manual (Latest version)

CAD Model