An non-lubricated, ringless piston engine without a conventional heat exchange system having a cross-head guide for guiding and restraining the piston within a cylinder of a two-stroke engine. The piston-bore radial clearance gap is maintained during engine operation by means of a capacitance sensor controlling a temperature equilibrium flow system within the piston head and the cylinder jacket. The engine operates at high speeds to minimize horsepower losses due to gas leakage, while benefiting from reduced friction losses resulting from absence of piston rings. Blowing gases are collected and returned to the combustion chamber from a pumping chamber formed beneath the piston and above the cross-head guide.
Charles D. Wood;