Simplify the following text for a Grade 6 native English-speaking person.
Original: Despite the shortcomings of length , weight , bearing friction , and torsional vibrations that led to the straight-8 's post-war demise , the straight-8 was the performance engine design of choice from the late 1920s to the late 1940s , and continued to excel in motorsport until the mid-1950s .
Simplified: The straight-8 was the engine design of choice from the late 1920s until the mid-1950s .