Abstract: A method of operating a pressure compensated fuel injector includes: filling a fuel chamber with a charge of fuel by closing an injector valve and circulating a fuel from a fuel source through a plurality of recirculating valves and a cap valve; then isolating the fuel chamber and the charge of fuel from the fuel source; then equalizing a pressure within the fuel chamber to a rising pressure outside the fuel chamber by reducing a volume of the isolated fuel chamber; and then activating a solenoid that is coupled to the injector valve, opening the injector valve; and then further reducing the volume of the isolated fuel chamber to apply an over pressure within the chamber, pumping fuel from the fuel chamber through the injection orifice.

Abstract: Methods and apparatus are described for a reciprocating combustion engine. A method includes operating a dual-piston engine including introducing a gas into a pair of combustion chambers; introducing a fuel into the pair of combustion chambers; compressing the gas; combusting the gas and the fuel; and exhausting combusted gases. Each of the pistons drives a reciprocating crankshaft that protrudes through a cylinder wall and cooperatively rotate a pair of rotors by engaging substantially sinusoidal cam tracks on the rotors. An apparatus includes a cam driven, concentric drive rotary-valve dual-piston engine.

Abstract: Methods and apparatus are described for a reciprocating combustion engine. A method includes operating a dual-piston engine including introducing a gas into a pair of combustion chambers; introducing a fuel into the pair of combustion chambers; compressing the gas; combusting the gas and the fuel; and exhausting combusted gases. Each of the pistons drives a reciprocating crankshaft that protrudes through a cylinder wall and cooperatively rotate a pair of rotors by engaging substantially sinusoidal cam tracks on the rotors. An apparatus includes a cam driven, concentric drive rotary-valve dual-piston engine.