Subaru engines were spotted by kitbuilders 20 years ago when the Japanese automaker came out with a boxer (horizontally opposed) design similar to that of Continental and Lycoming. That's where the similarity ends, however. The four-cylinder Crossflow models range in horsepower from 180 to 250 hp and the six-cylinders are rated at 250 to 350 hp (larger engines are turbocharged). The fours are 2,000 cc and the sixes 3,300 and there's only one way to squeeze all those ponies from that little displacement and that's to crank up the compression ratio and to run the engines at close to 5,000 rpm at full power. Of course, fundamental to the successful delivery of power to the prop is a Crossflow-designed gear reduction unit set at 2.34:1. Bore (92 mm) and stroke (75 mm) are the same for both engines and there's an ignition coil for each jug. Both use multi-port fuel injection to get the premium grade autogas into the chambers.