Chrysler’s third-generation Hemi introduced a two-spark-plug-per-cylinder ignition system and eventually spawned everything from a fuel-saving 5.7-liter truck engine to a 590-horsepower 426-cubic-inch showstopper. Along the way, displacements ranged from 5.7 to 6.4 liters, with technologies like MDS cylinder deactivation and variable crankshaft timing added throughout its run. Read on to find out how one ignition change led to an entire engine family.