In the following article, the author makes a good point about new engine designs: "In most cases these new designs only existed on paper. In other cases, the efforts were led by people who had no clue what it takes to break into the automotive industry. Think about it. In the last 100 years only three engines have made it into mass production: the gasoline engine, the diesel engine, and the rotary. And only Mazda has stuck with the rotary." In other words, it seems to be incredibly hard to get a new engine design into production.
This engine design from three years ago seemed like a sure thing:
And then last year there was this:
That seemed like a sure thing too.
But the author thinks that this new design has potential:
Eco Motors is the name of a new company that has come up with a radically new type of engine. It has two opposing pistons in two contiguous cylinders, connected to a common crankshaft in the middle of the engine. An electric supercharger provides boost on demand. It's a two-stroke engine with no valves, yet still achieves 90% scavenging efficiency with less oil consumption than a four-stroke engine. In other words, it's a two-stroke engine that can meet the strictest emissions standards. It can be made as a spark-ignited or compression-ignition engine, and the diesel version can meet emission standards without using urea.
The article contains two animations showing the new engine design in action.
This is not the only design with two pistons per cylinder - the Deltic diesel engine's piston arrangement uses the same approach:
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