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

Because of vibration.

For example, the displacement of the Lycoming O-360 flat-4 airplane engine is 360cid.
And of course the displacement of the LS1 V8 car engine is famously 350cid

The O-360 could theoretically have been used in cars, but you wouldn’t like the noise/ride/etc… We wear ear-pro headsets when flying a plane, even when it has a muffler installed (not all of them do)….
The LS1 is meanwhile rather heavy for airplane use…

(Note: Ignoring the expense difference due to bureaucracy/regulation and extensive engineering expense to make an airplane engine as-light-as-possible while still holding up – there’s a reason airplanes use air cooled engines. Also a reason why an O360 costs more than an entire car for just the engine.)….