Abstract: An internal combustion engine can include a piston moving in a cylinder and a junk head disposed opposite the piston head in the cylinder. The junk head can optionally be moveable between a higher compression ratio position closer to a top dead center of the piston and a lower compression ratio position further from the top dead center position of the piston. At least one intake port can deliver a fluid comprising inlet air to a combustion chamber within the cylinder. Combustion gases can be directed out of the combustion volume through at least one exhaust port. One or both of the intake port and the exhaust port can be opened and closed by operation of a sleeve valve that at least partially encircles the piston. Related articles, systems, and methods are described.

Abstract: An inverted combustion engine is described herein that can reduce or eliminate the amount of oil that leaks into a combustion volume of a combustion chamber. In some implementations, at least one piston of the combustion engine includes a crown that faces the combustion volume and a cavity on an opposing side of the crown that is configured to collect and contain oil that has entered the combustion chamber.

Abstract: An internal combustion engine is operable in an efficiency mode providing a first power output range between zero and a transition power output and in a power mode providing a second power output range between the transition power output and a maximum power output. The efficiency mode can include a first ignition timing and a first air/fuel ratio of the mixture to avoid premature auto-ignition, and the power mode can include a second ignition timing and a second air/fuel ratio of the mixture to avoid premature auto-ignition of the mixture. To further enable knock free operation of such an engine, turbulence can be imparted to the mixture to promote a faster burn duration and high temperatures that may lead to premature auto-ignition of the mixture can be avoided.

Abstract: An opposed piston internal combustion engine can include two opposed pistons (104, 110) moving reciprocally along respective axes of translation (202, 204) that are not collinear. First and second cylinder bores (502, 504) can be inclined to each other at an included angle (a). A combustion volume or chamber (114) can optionally be defined at least in part by crowns (102, 106) of the first and second pistons (104, 110) reciprocating in the first and second cylinder bores (502, 504), respectively. Related methods, systems, and articles of manufacture are described.

Abstract: Carburetor features, which can include but are not limited to varying slope angles in different sections of a multi-sectioned carburetor needle, can provide combustion mixtures to an engine that include a fuel-air ratio that is variable independent of the rate of air flow through the carburetor. Related methods, systems, articles of manufacture, etc. are described.

Abstract: A system and method are disclosed for fabricating and running an engine in two modes. The first mode is an efficiency mode having a high compression ratio and efficiency for low to medium loads. The second mode is a power mode having high power density for higher loads. The system may use a lean mixture in the efficiency mode, which mixture is made richer for more power in the power mode. The system may also use ignition timing to allow the efficiency mode and the high power mode to be at the same mixture.

Abstract: An internal combustion engine is operable in an efficiency mode providing a first power output range between zero and a transition power output and in a power mode providing a second power output range between the transition power output and a maximum power output. The efficiency mode can include a first ignition timing and a first air/fuel ratio of the mixture to avoid premature auto-ignition, and the power mode can include a second ignition timing and a second air/fuel ratio of the mixture to avoid premature auto-ignition of the mixture. To further enable knock free operation of such an engine, turbulence can be imparted to the mixture to promote a faster burn duration and high temperatures that may lead to premature auto-ignition of the mixture can be avoided.

Abstract: An internal combustion engine can include a piston moving in a cylinder and a junk head disposed opposite the piston head in the cylinder. The junk head can optionally be moveable between a higher compression ratio position closer to a top dead center of the piston and a lower compression ratio position further from the top dead center position of the piston. At least one intake port can deliver a fluid comprising inlet air to a combustion chamber within the cylinder. Combustion gases can be directed out of the combustion volume through at least one exhaust port. One or both of the intake port and the exhaust port can be opened and closed by operation of a sleeve valve that at least partially encircles the piston. Related articles, systems, and methods are described.

Abstract: A system and method are disclosed for fabricating and running an engine in two modes. The first mode is an efficiency mode having a high compression ratio and efficiency for low to medium loads. The second mode is a power mode having high power density for higher loads. The system may use a lean mixture in the efficiency mode, which mixture is made richer for more power in the power mode. The system may also use ignition timing to allow the efficiency mode and the high power mode to be at the same mixture.