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EcoMotors animation of dual-module opoc

EcoMotors, the developer of a new opoc (opposed-piston, opposed-cylinder) engine family (earlier post) has published an animation of a dual-module opoc on its website.

The opoc engine operates on the 2-cycle principle, generating one power stroke per crank revolution per cylinder. Each module consists of two opposing cylinders per module, with a crankshaft between them; each cylinder has two pistons moving in opposite directions. With a two-module application configured at the appropriate power level (to deliver a combined 480 hp), the opoc unit could deliver about 45% better fuel efficiency compared to a conventional heavy-duty diesel engine in a Class 8 truck, the company suggests, while delivering emissions at the US Tier 2 Bin 5 level (the 50-state level in the US for diesel light duty vehicles).

Screenshot of animation. Click to enlarge. Click here to see full animation.

The opoc engine in dual-module configuration is connected by an electrically controlled clutch. Select modules are deactivated at different points in the operating cycle to optimize fuel consumption (cylinder deactivation, but on a module basis). The clutch assembly is housed between two engine modules, and is engaged when both modules are running to deliver power from both modules through the drivetrain.

When the power of the second module is not needed, the clutch is disengaged, allowing the second engine to stop completely. This not only improves fuel economy, it also eliminates parasitic power losses in the primary module.



Ahhh yes - here we go again. Fancy animation and/or test results to generate more funding for an OPOC engine. No real engine with real test results...just nice pictures & numbers. Scam alert!

Nick Lyons

@ejj: I'm normally skeptical of the viability of 'revolutionary' engine concepts and their inventors/promotors, but Ecomotors may be the exception to the rule. They are backed by Khosla Ventures/Bill Gates, they have development deals with Navistar and others, they have five job openings (including four engineering types), etc. The odds are long for the success of any paradigm-shifting new engine design, but I'd bet on these guys over any of the others that are out there right now.

They are backed by Khosla Ventures
So was Range Fuels.

Yes, Khosla backing is not reassuring.

Dominik Lenné

Khosla said in an interview about venture capital (citing someone else?) that if a venture capitalist has more than 10 % successes in his investments, he has not been bold enough. AFAIR.
Having said that, I think Ecomotors has a real chance to get over the commercialisation threshold if they get enough money to solve the innumerous teething problems of a new concept, because the concept is in itself sound and because there are pros at work. (And because I like the concept, though I cannot quite understand why they chose to put the 2 cylinders in one flight instead side by side...)


With famous investors/supporters,
with great companies to team with,
with funds of many millions of dollars,
and with several years of experimental work,
EcoMotors finally did it: “published an animation”.

Maybe it’s time for Bill Gates to rethink the case.

EcoMotors presents their “dual-module” variable capacity arrangement as a wonder.

The idea:
OPOC module (a pair of opposed cylinders, a crankshaft and four pistons) is rid of unbalanced inertia forces and is well balanced as regards its inertia moments (the inertia torques is another story).
So, they connect conventionally the first OPOC module to the gearbox.
Then they put additional OPOC modules in a series, with special clutches (controlled electronically) between neighboring crankshafts.

The first OPOC module operates permanently.
The second module is engaged at medium to heavy loads (for instance during an acceleration, at an uphill etc).
The third module (if any) is engaged at heavy loads (say at top speed, at heavy acceleration etc).

One problem: The engagement / disengagement of the cylinders is in pairs.

Another problem: The first OPOC module operates permanently at medium – heavy load. From time to time its crankshaft transfers to the gearbox the torque of the rest modules. In the case of a serious problem in the first OPOC basic module, the complete engine stalls and the vehicle stops, even if the second, the third etc OPOC modules are at perfect condition.
As compared to a similar OPOC engine having a single crankshaft serving all the cylinders (non modular architecture), the “mean time between failures” shortens because the first module operates permanently at heavy load and because it undergoes additional loads during the engagement of the rest modules.

To sacrifice the reliability of a truck / car for the sake of a better fuel consumption, sounds “not so great idea”; especially when there are alternatives that improve both, reliability and efficiency.

Compare EcoMotors’ “dual-module” architecture to the way simpler architecture shown at ,
wherein the cylinders disengage one by one,
wherein there is no need for special clutches,
wherein the control is simple,
wherein the reliability of the engine is way improved: if the one module fails, the vehicle continuous with the other module “for ever”.
Here the “mean time between failures” extends as compared to the “mean time between failures” of each one of the engines.

Consider the case of a sport car having a powerful V-8 engine at the one side of the primary shaft of its gearbox, and a small green engine (like the single cylinder full balanced PatOP, or like the Fiat 500 TwinAir) at the other end of gearbox primary shaft.
Compare this solution to the new sport hybrid cars the sport-car makers launch in their effort to comply with the present and future emission regulations.

Manousos Pattakos

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