A term used to describe any engine that has hemispherical combustion chambers in its cylinder head Although a four-valve design is more efficient, a hemi head provides room for a pair of large valves and offers good breathing characteristics
Generally an engine with a combustion chamber resembling a hemisphere or round ball, cut in half
another famous abbreviation, this one referring to the shape of the combustion chamber in high-performance Chrysler-built engines of the 1950s and 60s, marketed under the names FirePower, Red Ram and D500 The chambers in the cylinder head were hollowed in the form of a section of a sphere or hemisphere, with valves opening directly into the concave chamber above the piston This shape markedly improved fuel combustion and performance, but it was expensive to build, because of the special castings and grinding, and the double banks of rocker arms needed to align the valves with their openings The Hemi was dropped in 1958 but returned in 1965 with 426 cu in displacement Nothing could match it on a drag strip or in sprints between red lights Two years ago the MoPar Performance Division began offering new Hemi blocks and rocker-arm assemblies to devotees of the good old days - at a price of $12,500 each!
A Hemi engine has a hemispherical shaped cylinder-head combustion chamber, like a ball cut in half
Engine using hemispherical -shaped (half of a globe or sphere) combustion chambers The valves are cocked at 45 degrees from the piston top Mopars, despite their fame, are not the only cars with hemi heads See engine type