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Another company developing fuel-efficient, opposed-piston engine

“Engine Smarts” by Tom Berg, Senior Editor

Earlier this year, we wrote about the OPOC engine from EcoMotors. Since then, we’ve discovered another opposed-piston engine, from Achates Power in San Diego.

The EcoMotors engine is a module consisting of a single cylinder with four pistons, in two sets of two pistons, one firing against the other, and all linked to a single, central crank (an animated illustration is at

The Achates layout is more traditional, with two pistons per cylinder, firing away from each other. Each piston is linked to a crankshaft at either end of the block, so there are two cranks. Fuel injection and air movement in and out of the cylinder is through ports in its center. It has no valves, so is also a two-stroker.

Pistons stay cooler and less heat is rejected than in current four-stroke diesels, which allows use of a smaller cooling system. Lab testing shows the Achates has 12 to 16 percent better brake-specific fuel efficiency. And if a modern four-stroke diesel’s thermodynamic efficiency is 45 to 46 percent, then the Achates engine’s “is on the order of 50 percent, and we have a road map to go to 55 percent,” says Achates’ president, David Johnson.

Achates says its engines improve fuel efficiency by more than 15 percent compared to today’s best diesel engines and approximately 55 percent compared to today’s conventional gasoline engine.

The Achates handles exhaust-gas recirculation with ease, and for maximum fuel efficiency it will use now-familiar exhaust aftreatment, including selective catalytic reduction, to meet regulations.

Johnson envisions using three or more cylinders for medium- and heavy duty truck engines. They’d weigh 10 to 20 percent less than today’s diesels. Installed in a truck, an Achates would cost about $1,500 less than now and still achieve the 10 to 15 percent better fuel economy called for in a recent scientific study presented to the White House, he says. Like EcoMotors, Achates has investor and government backing. Production is five years away.

This week, the company announced it’s making progress, as its engine nears 2,000 test hours and with the addition of 37-year industry veteran John Koszewnik as chief technical officer.

Koszewnik joins the company from FEV Inc. in Auburn Hills, Mich., as director of production development. As director of commercial engines at FEV, he also supported product development and strategic study projects for the automotive, heavy truck, locomotive and powertrain component supply industries. Prior to FEV, he worked for Case New Holland as senior vice president, construction equipment product development.

Prior to this, he was at Ford Motor Co. for roughly 30 years. During this time, Koszewnik was responsible for engineering of all Ford’s V6, V8 and V10 gasoline engines. He also led Ford’s North American Diesel effort, where he improved the durability and function of the Power Stroke engine while also reducing its cost, Achates says.

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Engine Smarts: Related News

6/17/2011 – Another company developing fuel-efficient, opposed-piston engine

Earlier this year, we wrote about the OPOC engine from EcoMotors. Since then, we’ve discovered another opposed-piston engine, from Achates Power in San Diego….

5/16/2011 – An Eastern Star?

Amidst endless chatter about electric power and even fuel cells, the good old internal combustion engine clearly isn’t going away any time soon….

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