Valve overlap—that crucial interval when both the intake and exhaust valves are open, expressed in degrees of crankshaft rotation—is typically a fixed parameter and always a compromise. For example, ...

In order to set a stage for what follows, let's first revisit some of the fundamentals involved in how valve timing relates to power output. And to further clarify how "power" is defined in the ...

Since the beginning of hot rodding, gearheads have endeavored to increase the performance of internal combustion engines through the optimization of valve timing. It's been proven time after time that ...

Decades ago (OK, half a century or more), there was a product advertised in many of the performance magazines called the Varicam. The idea was a set of springs attached to a centrifugal device that ...