Can’t we apply technologies such as VVT to make it perform just as well as a car with 4 valves per cilinder?
In: Engineering
There are a couple of reasons.
Most importantly, many smaller valves provides a greater total area for air to flow through when compared to two large valves. Air can only flow around the edges of a valve. So by using small valves, you get more “edge” per unit of area. This provides a more efficient pathway for air to flow.
An engine runs best when the air flowing into the cylinder is moving rapidly. If you move a little air through a large opening, it will move slowly. If you move a little air through a small opening, it will move rapidly. With four-valve engines, you can route the air into the engine so that only two of the four valves are used at low RPM. This causes the air flowing through two out of the four valves to move much more rapidly. This creates turbulence in the cylinder that is useful for mixing fuel, which leads to more efficient combustion.
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