ABSTRACT

Automotive engine design has been a game of compromise. Designing an engine for high engine speed meant it would be rough and inefficient at low speed. An engine designed for low-end torque meant limited high-speed performance. The automotive advances made possible through digital control are nowhere more impressive than in the performance of the internal combustion engine. The ideal valve operation changes with engine speed or load. In a perfect world, the opening and closing of each valve could be timed to the precise needs of the engine at a given load. Inlet port pressure varies with the opening and closing of each of the engine’s valves. When the intake valve opens, a significant port pressure drop ensues and is followed by a rapid upward pressure bump. The design of the mechanisms, and the general design of any modern engine, is a juggling act. Change one thing and three others are affected.