This engine is the ATP 6.5 turboprop. The engine is basically a surplus Solar APU core with an ATP designed PSRU and metering system. ATP claims to get 200 shp from the engine at 14 gph with an installed weight of about 200 lb. The secret to the piston-engine-like fuel economy, claims ATP, is their patent pending computerized metering system that utilizes automotive injectors and pumps.
ATP flew their ATP turbine powered RV-4 to Oshkosh last year. In an April 2003 Sport Aviation article, ATP claimed 40 flying hours on the engine in the RV-4.