I’ve noted Bruce Crower’s six-stroke engine before. Now Popular Science is lauding his Six Strokes of Genius:
A typical engine wastes three quarters of its energy as heat. Crower’s prototype, the single-cylinder diesel eight-horsepower Steam-o-Lene engine, uses that heat to make steam and recapture some of the lost energy. It runs like a conventional four-stroke combustion engine through each of the typical up-and-down movements of the piston (intake, compression, power or combustion, exhaust). But just as the engine finishes its fourth stroke, water squirts into the cylinder, hitting surfaces as hot as 1,500°F. The water immediately evaporates into steam, generating a 1,600-fold expansion in volume and driving the piston down to create an additional power stroke. The upward sixth stroke exhausts the steam to a condenser, where it is recycled into injection water.Crower calculates that the Steam-o-Lene boosts the work it gets from a gallon of gas by 40 percent over conventional engines. Diesels, which are already more efficient, might get another 5 percent. And his engine does it with hardware that already exists, so there’s no waiting for technologies to mature, as with electric cars or fuel cells.