Last year I wrote about Bruce Crower’s 6 stroke internal combustion engine and even now I still think about how ingenious that concept is. Here’s the basic idea, a 4 stroke internal combustion engine is what you and I have in our modern automobile and it’s 4 stroke because the engine strokes each piston 4 times through the complete combustion cycle. Crower’s engine add 2 more strokes that are steam driven.
Each piston in an engine rides on the crankshaft that moves it up once to compress the fuel/air mixture, down on the burn (gasoline engines burn fuel, diesel engines explode it), up to exhaust the waste gases, and down again to recharge the cylinder with fuel air mixture. That’s four strokes to complete the full cycle and throughout this the crankshaft also turns a camshaft with elliptical lobes that cause the intake and exhaust valves to open/close with precise timing in order to accommodate the piston stroke cycle.
About 60% of an engine’s energy, or more specifically the energy locked in the hydrocarbons that the engine uses as fuel, is lost as heat. Some of that heat is radiated through the metal components to the engine cooling system or through the lubricating oil as friction heats the metal. The bulk of this heat energy is lost right out the tailpipe.
The first automobiles were stream driven, typically utilizing a 2 cylinder steam engine that worked by converting a fuel source (typically gasoline or kerosene, which is close to diesel and essentially what jet fuel is today) into heat that converted water into steam which was then compressed and exhausted to create propulsion.
The remarkable thing about this engine system is how much power it created, it wasn’t uncommon for these 2 cylinder engines (with displacement per cylinder equal to a large displacement modern 8 cylinder engine) to produce just 20-30 horsepower but an astounding 700 ft. lbs. of torque. By contrast, the 8 cylinder 5.5 liter (335 cubic inches) engine in my car produces a little over 400 horsepower and 390 ft. lbs. of torque.
A 1910 Stanley Steamer with the 2 cylinder steam engine powered by a kerosene fired boiler could do 75 mph and get 10-12 mpg. This was in 1910!
The 6 stroke engine concept takes the waste heat generated by a 4 stroke engine and converts that heat energy into propulsion through adding 2 strokes that are steam driven. It uses existing engine hardware and relies on little new technology. Because the energy source is the heat already being generated there is no additional combustion. This is a fantastic concept that is completely doable today and by increasing engine efficiency by up to 40%, it lowers fuel consumption which then lowers emissions output.