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OPOC: The Two-Stroke Engine Revived by Michigan Company Is Cleaner and More Efficient


EcoMotors, a Troy, Michigan startup company revitalizes the two-stroke engine, making it 50 percent more efficient than currently-used four-stroke engines and less polluting. Even Bill Gates and Khosla Ventures invested a total of $23.5 million in them.

The engine they propose is called “OPOC” (Opposed Piston, Opposed Cylinder) and is actually a single-cylinder engine inside which lie two opposed pistons, joined by a single crankshaft. Of course, everything in the engine is controlled by a computer to get the maximum efficiency.

A two-stroke engine is different than that used in your car, which is a four-stroke engine. It has intake, compression, combustion and exhaust. In a two-stroke, all of these stages are completed within just two piston movements. The advantage is that the pistons can rotate the crank faster. The disadvantage would be that two strokes are normally gas-guzzlers and huge polluters when put aside four-stroke engines.

EcoMotors’ CEO, Don Runkle, says their OPOC engine is 15 percent more efficient than conventional ones. It is able to run faster, because each piston only has to travel half the distance it would normally have to in a classic two-strokes. Besides that, it has less parts and hence less friction is present while working. “A long list of 1 and 2 percent improvements” complete the list of enhancements that make the engine have such a high efficiency.

Runkle’s two-stroke OPOC engine also features an electric turbocharger that allows a varying compression ratio in the engine’s cylinders, maximizing efficiency. It also has asymmetrical port timing (opening the intake and exhaust ports at different times) which improves the efficiency of gas exchange. The third innovation is the high pressure injection and computerized control, which improves the overall cycle efficiency.

The OPOC engine is modular; you can assemble two or more to increase the efficiency to as much as 45 percent. Extra modules can be deactivated if not needed, without having to also spin them (they’re connected through an electronically-controlled clutch). Some advanced V8 engines also have the feature of turning off unused pistons, but they also turn along with the others, creating the so-called “parasitic loss.”

EcoMotors has secured an $18 million deal with Zhongding, an automotive supplier from China and is not testing the engine in all possible circumstances to determine its emissions, efficiency and power, so to have them ready when car manufacturers will present their interest in their product.

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  1. Quote from an interview of CEO Don Runkle of EcoMotors / OPOC:
    “The OPOC is cheaper, better, simpler, stronger, lighter and cleaner than any other power generating technology now or in the foreseeable future. . .The engine’s width is exaggerated a bit . . .”

    The PatOP engine at http://www.pattakon.com/pattakonPatOP.htm ,
    with basic module having only one cylinder and two opposed pistons,
    is better balanced than the OPOC engine of EcoMotors,
    it provides some 20% additional time (as compared to the OPOC) for the efficient injection and combustion of the fuel,
    it has constantly zero total force on the main bearings of the crankshaft (the connecting rods of the two opposed pistons remain constantly parallel)
    it takes the thrust loads away from the hot cylinder walls and away from the ports (lower lubricant consumption, better lubrication),
    has a built-in zero-cost “volumetric” piston-type scavenging-pump etc

    It seems EcoMotors’ CEO never heard about the OPRE and the PatOP opposed piston engines.

    Manousos Pattakos


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