Back in the early sixties, a car’s intake valve would open for a specific duration during a predetermined time in the engine’s four-stroke cycle. It was not an especially flexible system, but in the early days of motor vehicles, this wasn’t a big problem. In the engines of those days, idle and operating RPMs were often quite similar. However, as vehicles advanced in complexity, the range of potential RPMs widened, leading to greater compromises in systems with static valve timing. The need for a better solution lead to the rise of variable valve timing (VVT).