US Patent 7954465 Combined exhaust restriction and variable valve actuation

An internal combustion engine that includes both a variable valve actuation system and an exhaust restriction system to provide engine braking are disclosed. Variable valve actuation and exhaust gas restriction are carried out in response to one or more engine parameters such as engine speed, engine load, vehicle speed, and/or manifold temperature and pressure. Variable valve actuation and exhaust gas restriction may be controlled to provide selective engine performance during positive power operation and/or during engine braking operation.