Te ULPower 390iS mounted on the nose of an Arion Lightning.
An Engine in Search of an Airplane
The ULPower Six
By Tim Kern
When ULPower brought its 86-hp UL260i to the U.S. Sport
Aviation Expo at Sebring, Florida, in 2007, it caused a
stir. (It is now rated at 97 hp.) Here was a conventionally
laid-out, four-stroke, four-cylinder, air-cooled, direct-drive
engine that incorporated the virtues of tradition but with
modern engineering, metallurgy, electronics, and fuel
systems. It took a while to gain acceptance, but now with
thousands of fleet hours, the ULPower four-cylinder engines (now up to the UL350iS, rated at 130 hp) are popular
and gaining both original equipment manufacturer (OEM)
and experimental builder acceptance.
At AERO Friedrichshafen in 2012, ULPower displayed a sixcylinder 390i (145 hp) and iS (160 hp), and announced its
big-six 520i and iS. And so, at the Sun 'n Fun International
Fly-In and Expo in April of 2013 came the 170- to 180-hp UL-
30
Vol.2 No.8 /August 2013
Power 520i six-cylinder family, the promised enlargements
of the 145/160 hp 390. But where do these sixes fit? The 520
family is way more powerful than engines of comparable
size and weight. That sounds like a good thing, except…
what design is looking for this engine?
The 520 is a 5254-cc flat six. Like all ULPower engines, it's
air cooled and direct drive, with fuel injection and dual
electronic ignition.
Good practice is evident in the overall design, and most
parts are manufactured from billet, on a 150-tool CNC
machining center. Some notable features: The wet sump
is deeply finned and incorporates a windage tray, and long
studs couple opposing unlined SAE 4140 finned steel billet
cylinders, straight through the aluminum alloy case. The
Photography by Tim Kern