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Camless Variable Valve Actuation (VVA) technologies have been known for improving fuel economy, reducing emissions, and enhancing engine performance. VVA can be divided into electro-magnetic, electro-hydraulic, and electro-pneumatic actuation. This paper presents an electro-hydraulic VVA design (called GD-VVA-2) that offers continuously variable timing and two discrete lifts (low lift S1 and high lift S2). The lift control is achieved through a lift control sleeve, which is hydraulically switched between two mechanically defined positions to provide accurate lifts. The low lift S1 has a wide design range, anywhere between zero and the high lift S2, i.e., 0 < S1 < S2. If S1 ≥ 0.5*S2, engine valves may operate at the low lift during most of a typical drive cycle. Operation at the low lift reduces energy consumption significantly. The GD-VVA-2 design offers compact package size and reasonable energy consumption.

To obtain the maximum output power and fuel economy from an internal combustion engine, it is often necessary to detect engine knock and operate the engine at its knock limit. This paper presents the ability to detect knock using in-cylinder ionization signals on a large displacement, air-cooled, “V” twin motorcycle engine over the engine operational map. The knock detection ability of three different sensors is compared: production knock (accelerometer) sensor, in-cylinder pressure sensor, and ionization sensor. The test data shows that the ionization sensor is able to detect knock better than the production knock sensor when there is high mechanical noise present in the engine.