Formed in 2006, ULPOWER Aero Engines is a small Belgian company which started as a joint venture by a number of individuals and companies. Their intention is to develop and manufacture a light weight aero engine where power and reliability is priority number one.
ULPower engines have been developed specifically for use in light aircraft and are manufactured to the highest standards with fully electronic ignition and multi-point fuel injection (FADEC) system as standard equipment.
Their truly modern engines feature dual electronic ignition (with variable timing), excellent power-to-weight ratio, and high fuel efficiency in a conventional configuration: air-cooled, direct drive, horizontally opposed 4 or 6-cylinder (boxer). Full aerobatic and helicopter configurations are also available from them.
On these pages we are going to describe the different engine models ULPower manufactures and continue with the larger versions.
There are, at this moment, seven different versions of the UL390 and UL520 engine range. In the table below we summarize the most important aspects and specifications compared between each of these models:
| Engine Model | UL390i | UL390iS / UL390iSA |
| Displacement | 3900 cm3 [237.2 in3] | |
| Bore | 105,6 mm [4.157 in] | |
| Stroke | 74 mm [2.913 in] | |
| Compression Ratio | 8.16 : 1 | 9.1 : 1 |
| Firing Order | 1-4-5-2-3-6 | |
| Direction of Rotation | Clockwise - cockpit view | |
| Max Torque (ISA) | 320 Nm [236 ft.lbf] @ 2800 RPM | 370 Nm [272.9 ft.lb] @ 2800 RPM |
| Power Rating (ISA) | 140 hp @ 3300 RPM 130 hp @ 2800 RPM | 160 hp @ 3300 RPM 145 hp @ 2800 RPM |
| Installed Weight | 100 kg [220.5 lbs] | |
| DC Output | 50 A | |
| Oil Capacity | 4 l [1.05 US gal] | |
| Min. Fuel | 95/98 Octane (AVgas 100LL) | 98 Octane (AVgas 100LL) |
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Note: the UL390iSA is the same as the UL390iS but with an adapted oil system to allow inverted flight.
| Engine Model | UL520i | UL520iS(RR) / UL520iSA |
| Displacement | 5254 cm3 [213.77 in3] | |
| Bore | 105,6 mm [4.157 in] | |
| Stroke | 100 mm [3.937 in] | |
| Compression Ratio | 8 : 1 | 8.7 : 1 |
| Firing Order | 1-4-5-2-3-6 | |
| Direction of Rotation | Clockwise - cockpit view | |
| Max Torque (ISA) | 425 Nm [313.5 ft.lbf] @ 2600 RPM | 465 Nm [343 ft.lb] @ 2800 RPM |
| Power Rating (ISA) | 180 hp @ 3300 RPM 170 hp @ 2800 RPM | 200 hp @ 3300 RPM 180 hp @ 2800 RPM |
| Installed Weight | 108 kg [238.1 lbs] | |
| DC Output | 50 A | |
| Oil Capacity | 4 l [1.06 US gal] | |
| Min. Fuel | 95/98 Octane (AVgas 100LL) | 98 Octane (AVgas 100LL) |
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Note: the UL520iSA is the same as the UL520iS but with an adapted oil system to allow inverted flight. The UL520iHPS is designed for helicopter and gyrocopter applications. The UL520iSRR is a reverse rotation version developed for pusher and twin engine aircraft.
Text and images used with permission of ULpower.
