Opposed Piston and Other Engines that could deliver 100 mpg

1. EcoMotors is developing high-efficiency engines — specifically the unique opoc (Opposed Piston Opposed Cylinder) engine — for use in cars, light trucks, marine applications, agricultural vehicles, stationary generators, etc.; essentially anywhere conventional gas or diesel power is utilized. They have stackable engines. Below is a picture of a dual module Ecomotors OPOC engine.

EcoMotors, a startup building an efficient engine, has raised a $32.5 million Series C round led by Braemar Energy Ventures, and including previous investors Khosla Ventures and Bill Gates in 2012. The four-year-old company’s engine design includes stackable modules, one of which can be shut off when it isn’t needed, and the startup has said its engine could deliver a 100 MPG for highway driving in a 5-passenger car.

EcoMotors said this morning that the funding will help it create diesel engines with customers, including Navistar and Zhongding Holding Group. The company will also use the funds to make a gas-version, in addition to its diesel-version. Eventually EcoMotors will also develop a compressed natural gas version, too.

2. Achates Power, an engine developer based in San Diego, claims its opposed-piston, compression-ignition two-stroke diesel (at right) can power a 40-mpg (highway) economy car like the Ford Fiesta with a 50 percent or more improvement. Yes, 60 mpg is possible, the company says, while also meeting the tough smog/greenhouse gas emissions regulations that automakers will soon face.

According to CEO Dave Johnson, the Achates innovations include two cylinders in one combustion chamber and eliminates both the valve train and cylinder head, “giving us tremendous efficiency advantages.” It also uses less raw material and fewer components, but a completely conventional manufacturing process, which Johnson says will dramatically lower automakers power plant costs. Diesels also have an inherent fuel economy advantage.

Achates Power has a paper describing the application of an OPOC engine for a military ground vehicle

After more than 3,000 hours of dynamometer testing, Achates Power has demonstrated a 21% fuel efficiency improvement with our engine as compared to a leading medium-duty diesel engine. In addition, having high specific power and lower fuel consumption and heat rejection to coolant, our engine has also met the combat vehicle requirements.

3. The Transonic Combustion system (TSCiTM) is a new combustion process for the gasoline internal combustion engine. The TSCiTM combustion process utilizes direct injection of fuel into the cylinder as a supercritical fluid based on the patented concept of injection-ignition. Supercritical fuel promotes rapid mixing with the contents of the cylinder which, after a short delay, results in spontaneous ignition at multiple locations. Multiple ignition sites and rapid combustion combine to result in optimum heat release and high cycle efficiency. Other advantages are the elimination of droplet burning and increased combustion stability that results from multiple ignition sources.

Independent engine test results, by a recognized international test authority, have been attained over a range of speed/load operating conditions to show fuel consumption reductions of 20% at critical engine test conditions. The results have been correlated with thermo-dynamic modeling to provide a detailed understanding and correlation of the fundamental thermodynamics.

The potential of the technology is to provide real world fuel consumption reductions of 25% to 30% in gasoline fueled passenger cars with corresponding reductions of greenhouses gases.

Transonic Combustion’s TSCiTM is an innovative fuel injection system comprised of fuel injectors, fuel heaters, an electronic control unit, and a high-efficiency fuel pump. The technology is optimized for gasoline engines.

4.The Grail engine looks much like a traditional two-stroke engine, but incorporates some weight-saving refinements that make it less expensive to manufacture.

Like other two-stroke designs, this compact engine has a reed-valve intake and alternating combustion and exhaust strokes. The way it runs, however is a bit different.

During operation, the piston travels up and creates negative pressure below it, pulling air in through the carbon-fiber reed valve. When the piston is then forced down by combustion, the reed valve closes. The piston continues down, compressing air in the crankcase chamber and forcing it through an oil-separating loop at the bottom of the piston. Then, when crankcase pressure exceeds the combustion-chamber pressure, the reed valve opens, forcing air through a hole in the center of the piston. This pushes exhaust air out and pulls fresh air in. As the piston moves up, the intake and overhead exhaust valves close, fuel is injected, and the mix is ignited by a spark plug.

With the piston and combustion chamber constantly exposed to cool air moving through the center of their masses, fuel can be injected at anytime without it instantly igniting, and this cuts down on NOx. The engine can burn almost anything as fuel. And it is light for its power output; a 25-lb engine puts out 5 hp, while a 40-lb engine generates 100 hp. The engine is inexpensive to manufacture with many parts being made using simple castings. And the modular design lets it be scaled up by daisy-chaining single-piston engines onto a single crankshaft to make a multicylinder, in-line engine.

Benefits of the Grail Engine:

* Engine produces power every revolution per-cylinder as desired.
* Less pumping losses allows greater air flow through cycles
* On-the-fly variable compression ratios at full range of RPM’s
* Independently configure each cylinder according to vehicle load.
* On-the-fly multiple fuel sources
i.e. fossil fuels, hydrogen etc…
* Built in Super Charger for pre-compressing intake charge
* Built in inter-cooler for cooling intake air-to-combustion chamber
* Potential for forward & reverse operation
* Lower parts count attributing to lower manufacturing costs
This will allow for reduced costs per unit
* Virtually no industry retooling required
* Liter for liter outclasses all four stroke engines
In power to weight ratio and thermal efficiency
* Redefines the standard of efficiency for Internal Combustion Engines
* The engine can achieve the Miller Cycle and HCCI simultaneously.
Thus making the Grail Engine a true hybrid.
* One Liter Engine Projections based upon vehicle weight and engine demand:
100+ MPG’s
180 ft lbs Torque
200 Horse Power

5. A startup called Pinnacle Engines emerged with just such a technology and a $13.5 million round of venture capital backing, and the company says it can deliver an engine with 30 to 50 percent better fuel economy.

Pinnacle says it has created an entirely new four-stroke engine with a design that uses opposed-pistons and can operate in different modes depending on operating conditions, making it more efficient. The engine also has efficiencies via variable valve timing, direct injection, and turbocharging. Pinnacle says it plans to commercialize its engine by 2013.

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