The term “Hemi” engine was trademarked by the Chrysler Corporation in 1964; however, the concept and same technology is used by other companies under different names. The Multi-Displacement System (MDS) is also a Chrysler-developed technology involving variable engine displacement. It is similar to the Active Cylinder Control, Active Fuel Management and Variable Cylinder Management technologies developed by Mercedes-Benz, GM and Honda, respectively.
The Chrysler Hemi Engine
The Hemi engine was an internal combustion engine designed by Chrysler that utilized a hemispherical combustion chamber. This allowed the valves to be in-line rather than side-by-side, which resulted in a simpler airflow and larger valves. This powerful engine found use in the XP-47 aircraft where it generated a maximum power of 2,500 to 3,500 horsepower.