Question

1. What is valve overlap?
2. Why is some amount of valve overlap desirable?

Define the term zero overlap.

Answer 1

A. Valve overlap is a term related to the internal combustion engines. It is defined as that period of time for which both the inlet and outlet valves are open simultaneously for a brief period of time. during the end of the exhaust stroke as the exhaust valves are to be closed by Normally, this occurs releasing the exhaust gases and inlet valves open a little prior to the closing of exhaust valves. B. Valve overlap in essential in the function of IC engines as it allows more time for the inlet air to flow into the cylinder when the speed of the engine becomes faster. The inlet air while entering the cylinder also pushes the leftover exhaust gas outside the engine. Zero overlap means the inlet and outlet valve open and close independently and there is no mutual overlap among them.