An apparatus for adjusting power and noise characteristics of an internal combustion engine comprises a wall configured to define an engine cylinder that includes a bore and a compression relief passage. A compression relief valve is configured to selectively adjust fluid flow capacity of the compression relief passage. A manifold is configured to be in fluid communication with the exhaust passage and includes an exhaust bypass valve to permit exhaust to at least partially bypass a noise suppressor. Operational characteristics of the engine can be adjusted along a range that extends from a first set of operational characteristics present when both the compression relief valve and the exhaust bypass valve are in a fully open position to a second set of operational characteristics present when both the compression relief valve and the exhaust bypass valve are in a fully closed position.

A propulsion system coupled to a vehicle. The system includes a diffusing structure and a conduit portion configured to introduce to the diffusing structure through a passage a primary fluid produced by the vehicle. The passage is defined by a wall, and the diffusing structure comprises a terminal end configured to provide egress from the system for the introduced primary fluid. A constricting element is disposed adjacent the wall. An actuating apparatus is coupled to the constricting element and is configured to urge the constricting element toward the wall, thereby reducing the cross-sectional area of the passage.

A heating system is configured to produce heated fluid. The system includes a source of primary fluid, a diffusing structure comprising an outlet structure out of which the heated fluid flows, at least one conduit coupled to the source and the diffusing structure and configured to introduce to the diffusing structure the primary fluid, and an intake structure coupled to the diffusing structure and configured to introduce to the diffusing structure a secondary fluid accessible to the system. The heated fluid includes the primary and secondary fluids.

A heating system is configured to produce heated fluid. The system includes a source of primary fluid, a diffusing structure comprising an outlet structure out of which the heated fluid flows, at least one conduit coupled to the source and the diffusing structure and configured to introduce to the diffusing structure the primary fluid, and an intake structure coupled to the diffusing structure and configured to introduce to the diffusing structure a secondary fluid accessible to the system. The heated fluid includes the primary and secondary fluids.

An exhaust control device for engine configures an exhaust system by joining exhaust pipes at a collecting pipe. The exhaust pipes are coupled to a plurality of respective cylinders. At least two types of exhaust valves are configured to perform an exhaust control at different parts in the exhaust system. The exhaust control device for engine includes first exhaust valves, a second exhaust valve, and an actuator. The first exhaust valves are mounted to a plurality of communicating pipes and communicating the predetermined exhaust pipes. The second exhaust valve is mounted to the collecting pipe. The actuator is configured to drive to open and close the second exhaust valve. The first exhaust valves are configured to be driven to open and close corresponding to an actuating region of the second exhaust valve.

An apparatus for adjusting power and noise characteristics of an internal combustion engine comprises a wall configured to define an engine cylinder that includes a bore and a compression relief passage. A compression relief valve is configured to selectively adjust fluid flow capacity of the compression relief passage. A manifold is configured to be in fluid communication with the exhaust passage and includes an exhaust bypass valve to permit exhaust to at least partially bypass a noise suppressor. Operational characteristics of the engine can be adjusted along a range that extends from a first set of operational characteristics present when both the compression relief valve and the exhaust bypass valve are in a fully open position to a second set of operational characteristics present when both the compression relief valve and the exhaust bypass valve are in a fully closed position.

A heating system is configured to produce heated fluid. The system includes a source of primary fluid, a diffusing structure comprising an outlet structure out of which the heated fluid flows, at least one conduit coupled to the source and the diffusing structure and configured to introduce to the diffusing structure the primary fluid, and an intake structure coupled to the diffusing structure and configured to introduce to the diffusing structure a secondary fluid accessible to the system. The heated fluid includes the primary and secondary fluids.

A heating system is configured to produce heated fluid. The system includes a source of primary fluid, a diffusing structure comprising an outlet structure out of which the heated fluid flows, at least one conduit coupled to the source and the diffusing structure and configured to introduce to the diffusing structure the primary fluid, and an intake structure coupled to the diffusing structure and configured to introduce to the diffusing structure a secondary fluid accessible to the system. The heated fluid includes the primary and secondary fluids.