China To Build EcoMotors' Efficient Opposed-Piston Engines

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EcoMotors OPOC engine diagram

EcoMotors OPOC engine diagram

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History makes fools of us all sometimes, none more so than when we dismiss certain ideas out of hand, only for them to come back years later and eat our words.

That's why we're always intrigued by companies claiming to reinvent the engine. One of them might well do so, given the right resources.

For EcoMotors, Detroit-based developers of an opposed-piston diesel engine, those resources are being provided in a $200 million deal to build its engines in China.

According to Automotive News, EcoMotors' partner Zhongding Power will build a new Chinese plant to build up to 150,000 of the turbodiesel engines per year. High-volume production is scheduled to begin in 2014.

EcoMotors' OPOC engine, standing for Opposed Piston Opposed Cylinder, is different from the Free Piston Linear Generator we recently featured.

While the Linear Generator ditches a crankshaft in favor of pistons mounted on air springs, each cylinder in the OPOC has two pistons, facing each other. The two-stroke design eliminates valvegear and cylinder heads and develops one power stroke, per crank revolution, per cylinder.

Its backers say the OPOC engine could prove up to 30 percent more efficient than a conventional design, as well as being lighter and more compact.

Ecomotors and Zhongding's initial market will be to the makers of electrical generators, and for off-road and commercial vehicles. Chinese companies are "aggressively" seeking new powertrain technology right now in a growing market, making the timing of EcoMotors' deal just about perfect.

Whether the engine will appear in regular automobiles or not is an unanswered question. Critics of the technology say it isn't clean enough for road cars, thanks to the two-stroke design--but EcoMotors says the engines will meet government regulations on emissions.

With strong Chinese investment, we're not writing this one off just yet--history is waiting right around the corner to make fools of the opposed-piston engine's doubters...


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Comments (12)
  1. If you look at the numbers a stock 350 SB Chevy beats it in weight and power if you look at the numbers.

    This style is too heavy and complicated. Good the Chinese have it.

    Better to just use 1 cylinder with just 2 pistons and size or number of them to suit the app.

    You can just use a chain or gears between the cranks you can take off power from at the rpm up or down from running rpm. Simple, balanced, powerful and eff. Add a turbo or supercharger on the intake for more power.

    Say use a 20hp one for a car and 100hp for a semi with 4x's the electric drive hp, a 5-80 mile battery pack. Then add a steam/heat engine on the exhaust heat and you'd double to triple mileage.

  2. It seems to me that a fairly clean 2 cycle direct injection engine can be made because with a turbo charger you can blow all of the exhaust out of the cylinder and it just fills up with air. If some of that air blows all the way through there is no unburned fuel in it so it will be relatively clean.

  3. 1) 2-stroke engines need some low RPM boost to start, which a TC does not provide. So the OPOC needs a SC & a TC, which doesn't help lower its cost. (Note, no pics of the actual OPOC prototype engine are ever available in these "press releases".)
    2) When I worked at EM, oil consumption on my engine was 2 qts/hr, definitely not "clean". The reason is that the internal engine blowby is 50%. Ask any engine builder if they would ship an engine with 50% blowby.
    3) Ask any Roush dyno engineer who has ever worked on the OPOC engine how many times the EPA showed up b/c of the black smoke coming out of the cell.

    Moral is just like CVTs, this OPOC idea looks great on paper but fails miserably when the concept is put to actual practice.

  4. So no data/pics/vids supporting EM's claims are attached to this article? This is just another marketing ploy by EM to fool the public that they have a working engine, which I, along with many other ex-EM employees, know is pure BS.
    Why was there no "press release" when EM laid off everyone in their vehicle integration group? Could it be because they failed so many dyno engines that they had no other engines left for vehicle integration efforts? Or why no "press release" when John Coletti, EM's COO, mysteriously resigned without reason? Could it be John lost faith in the engine but didn't want to hurt EM's chances of luring more ignorant investors/customers?

  5. Would seem more effective to run a car on electric power,
    and use the new gas engines for battery charging.
    (Capstone has a 30 Kw turbine generator that runs on many fuels)

  6. How are the pistons lubricated in the cylinder? I cannot tell from the 3D model cutout.

  7. The whole idea to develop a more efficient opposed piston diesel engine sounds interesting. The Detroit diesel make one of the best diesel engines in the world. The engines are becoming small and light weight and they are more economical and high on power.

    More info on exciting green cars at :

  8. Junkers did this in the 1930's

  9. This article in Fox News( is disgusting. These engines have been around since World War 2 where they were used as submarine engines, just on a much larger scale. They were salvaged after the war and many were turned into generator sets to power military sites. I had the opportunity to run one of these gensets at Eglin AFB in 1982. It was a Fairbanks Morse Horizontally Opposed 10 cylinder engine just like this one: Nothing new about it.

  10. Cullen, remember the F-M OP's carried TWO cranks, an upper and a lower, with the pistons meeting crown to crown at the center of the cylinder liner.
    These engines worked very well in a genset app with a consistent RPM and a fairly heavy load; in anything else? not good at all, these engines dont like thermal cycling.
    Weve run them in tugboats at my company, no likey.
    You know to pull a single liner the top 'coffin cover' has to be lifted off, all the upper rods disconnected and the upper crank removed? Not a job for those without the luxury of a lot of downtime. :.P
    Good luck to the Chinese with thier engine, it may not pass emissions here, but if its going to be used in 3rd world countries, I dont think they care.

  11. really awesome post and i liked it all what WePresent

  12. Why the F&%$#! would you want CHINA to manufacture these engines?Haven't you been reading about the Bay Bridge parts re-call or the colapse of the skyscraper due to insufficient concrete footings?China has VERY DIFFERENT manufacturing standards which basically means,"just enough to pass inspection" or substitute whatever will work.Remember the other recalls on child's toys,pet food as well as prescription and over the counter medications.

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