Auto Racing: High Performance Autos, boss 429 mustang, hemi motor

Question
What is meant by the term "hemi-engine?"

Answer
Kevin-

  "Hemi" is short for "hemispherical".  The combustion chamber of the cylinder head is a dome shape and the valves open opposite of each other.  It's actually fairly complex as far as the valvetrain is concerned.  These days a Hemi isn't something to really write home about.  Back in the 60's when the horsepower wars were in full swing, Hemis were just about king of the hill.  A Chrysler 426 Hemi could easily surpass 450hp from the factory (though they were rated much lower for insurance purposes).  I honestly think the new Hemis, while mildly impressive, are just a desperate attempt by Chrysler to cling to their one big claim to fame.  Ford also had a "semi-hemi" motor (the combustion chambers weren't entirely rounded to create a half circle) in the Boss 429 Mustang and Torino lines.  If memory serves me, there may be an in depth and illustrated tutorial on www.howstuffworks.com of Hemi motors and their designs.  Hope this helps.

Steve