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New Frontiers in Combustion:
The OPOC Engine

December 2, 2011 by Matt

EcoMotors OPOC Engine Motor Opposed Piston Opposed Cylinder

Call me a pessimist, but as much promise as this engine shows, I just don’t see it going anywhere.

It’s not for lack of technical merit. The EcoMotors Opposed-Piston Opposed-Cylinder (OPOC) 2-stroke diesel engine exhibits a thermal efficiency of close to 50%, meaning that around half the energy delivered to it is converted into work, compared with 20-30% for the average gasoline engine. It’s compact, smooth, efficient, powerful and arguably less complex than the typical conventional engine, what with its lack of valvetrain or ignition system.

EcoMotors OPOC Engine Motor Opposed Piston Opposed Cylinder

Essentially a two-stroke horizontally-opposed diesel engine with an extra pair of pistons where the cylinder heads would otherwise be, linked to the crankshaft via long connecting rods, the OPOC engine employs an exhaust-driven turbocharger to deliver positive pressure to fill the cylinder volume and push out the exhaust. The engine avoids the typical two-stroke disadvantage of losing much of the intake charge out the exhaust by staggering the port openings relative to the piston positions—impossible on a conventional single-piston reciprocating engine. All the moving parts are carefully synchronized in a kind of mechanical ballet, keeping bearing loads to an absolute minimum and permitting a relatively lightweight engine block.

So why the pessimism about its potential for success? History. There have been no shortage of alternatives to the conventional reciprocating engine over the years, and none of them have caught on. The closest to parity, of course, has been the Wankel engine, but even it was relegated to a far, far distant second place, and ceased production entirely this past year. So in spite of its fear-dissuading superficial resemblance to normal boxer engine, the OPOC engine’s extra dose of unfamiliarity will be its undoing in the marketplace. I suppose, if all else fails, the engine may turn out to have a fruitful career in non-commercial applications such as military vehicles and the like, but I just don’t see it catching on beyond that sphere of use.

Click on the jump below to view a pair of clips, the first an animation of the engine in action, and the second representatives of the development team explaining the engine’s intricacies.

Filed under: News, Technical

1 Comment

  1. Tom Adams says:

    I like it…

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