The straight-8 was quite popular in the past in racing and luxury cars because of its smooth characteristics while running. But, the length of the engine required the usage of long compartment for it. Because of it the modern vehicles find it inconvenient to use this basic design.
Besides this, torsional vibrations are produced in camshaft and crankshaft because of the engine length. They can greatly affect the performance and reliability of the engine at higher speeds. There is also the risk of a phenomenon called the crankshaft whip.
It is caused at higher engine rpm when the centrifugal force effect crank throws. The physical contact could be made between the crankcase walls and connecting rods due to it. It may further lead to the destruction of engine.
Because of this reason the designing of this engine has been greatly reduced in the modern time. The short and sturdy engine called V8 has become the more popular choice.