Why would engine designers opt to include more cylinders in an engine instead of increasing the displacement?

Question

For example, why would a car manufacturer opt to to use a 2.0L in line six instead of a 2.0L in line four in a vehicle. Are the benefits of including more cylinders in an engine worth the added complexity?

In: Engineering

Answer 1

More smaller cylinders run smoother and get better performance at high speeds. When you’re moving that fast, the time for air and fuel to enter the cylinder and exhaust to leave starts to really matter, and a smaller cylinder can do that exchange quicker. These are positives for passenger cars, so many of them will feature V6 and V8 engines instead of I4s with larger displacement. 

Fewer, larger cylinders give you more torque and a simpler design, but also more noise and vibrations to deal with. These are often used for farm equpment, generators, and other industrial applications.