What is the difference between a normal engine and a hemi?

Question

What is the difference between a normal engine and a hemi?

Answer 1

some heads have combustion chambers that are heart shaped ( gm ) hemi ( Chrysler ) heads are round like a sphere  cut in half ( a dome )and the 1965 and up till the motor  production run ended hemi heads had the spark plug between the intake and exhaust valve ( in the center of the head in the middle ) new hemi heads have the plug on the side so its a hemi but its not related to the 426 hemi and previous

hemi motors like the 390. they just use to name to market and make people want the name. ford had a can am 427 motor that had hemi heads also and the 429 boss which they called a semi hemi because the heads combustion chambers where some what hemispherical  

Answer 2

Hemi refers to the shape of the heads. A number of newer vehicles have hemispherical heads, Mopar just does a better marketing job!