Why do American semi-trucks (18 wheelers etc) exclusively use inline 6-cylinder engines, no matter if it’s a Mack, Detroit Diesel, Cummins, or Volvo-built engine?

Question

I get why they are diesel, but why are they all of the inline 6-cylinder configuration? Why not V6 or straight 8 or freakin huge inline 4-cylinders?

In: 715

Answer 1

A lot of stuff is easier on a straight 6. One head. Simpler valve train. They also tend to run smoother and require less balancing than a V configuration.