ORIGINAL: Jeremiah 29:11

The "Hemi Engine" is a design of internal-combustion engines in which the cylinder head's combustion chamber is of hemispherical form.


The hemispherical combustion chamber design puts the intake/exhaust valves in-line, rather than side-by-side, allowing for better flow of air through the head (although the inlet and exhaust valves are not simultaneously open and there is no continuous flow).

Chrysler introduced a modern Hemi in 2002. This engine is not a true hemispherical head engine; it has a polyspherical combustion chamber, but retains the Hemi's traditional inline perpendicular valves. It is available in two sizes; 5.7 and 6.1 liters. Some versions of the 5.7L, including most 2006 production units, utilize a variable displacement technology called the Multi-Displacement System (MDS) to improve fuel economy. Also, at the 2005 SEMA show, Chrysler unveiled a 505-horsepower 6.4L HEMI which will be available as a racing crate engine and might find its way into production, perhaps with reduced horsepower.

Bottom line are the new Hemi's are not like the Hemi's of old except the inline perpendicular valves. Apparently, the shape of a Hemi combustion causes a lot of excess gases that the EPA has a problem with. But what a great marketing tool because just saying Hemi conjures up in the mind a muscle car that has no equal.