The art of porting cylinder heads, whether by hand or by CNC machine, is a valuable part of blueprinting detailed engine builds or overhauls, and surprisingly subtle changes can determine how efficiently the engine will breathe.
AeroTek Aviations Beaver-size amphibious kit airplane, the Grizzly, showcases the company's 550-shaft-horsepower Pratt & Whitney PT6A engine conversion, which has also flown in the Murphy Moose. By Ed Wischmeyer.