Actually, in the late 1920's Cessna did make engines -- or at least it
modified Anzani engines for more power. There was a shortage of good,
modern (for the time) engines in the 100-150 HP range, and Cessna had
airplanes to sell. So they figured out how to replace the self-actuating
intake valves with cam-actuated ones.
In the end it only sold them a few planes, but it does make an
interesting bit-o-trivia.
--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com