Abstract: An exhaust port controlling arrangement for an internal combustion engine having both main and auxiliary exhaust ports. A main control valve cooperates with the main exhaust port for varying the timing at which the exhaust port opens in response to engine speed. An on/off auxiliary control valve is positioned in a passage leading from the auxiliary exhaust port for opening and closing the flow through the auxiliary exhaust passage in response to an engine condition. Means retard the opening of the main exhaust port upon opening of the auxiliary exhaust ports to improve the power and torque curves of the engine.

Abstract: An improved compact induction system for a V type engine including a pair of plenum chambers disposed in the valley of the V. The plenum chambers are shorter than the respective cylinder banks and serve high speed intake passages of the respective cylinder bank and some longer, low speed intake passages of the adjacent cylinder bank and some low speed intake passages of the other cylinder bank. All of the low speed intake passages have the same length.