last time die-hard Chevy fans had a new engine
to really get excited about was in 1962-63 when
Chevy introduced the "porcupine motor" big block
for use by NASCAR racing and drag racing applications.
That engine/cylinder head design is basically
the forerunner of all current 500-800+ inch
wedge engines. Variations of that basic engine
introduced forty years ago power a majority
of drag cars from (barely) legal seven-second
gasoline-burning street cars to six-second,
200-mph Pro Stockers, to five-second alky-burning
dragsters and funny cars.
For decades racers and engine builders have known in their heart of hearts that the venerable Chrysler Hemi head was more efficient and capable of making more power easier than the wedge head. The main reason being that the intake and exhaust valve in the Hemi are located exactly 180 degrees apart, facilitating more and better air-flow characteristics than Chevy, Ford or even Chrysler wedge heads.
Diehard Chevy and even Pontiac racers have tried to find ways to have a hemispherical combustion chambered-head on their Ford or Chevy. In the early years, Zora Arkus-Duntov developed a Hemi head that bolted onto the Ford and Merc flatheads. The late Mickey Thompson even had some "Hemi" Pontiac heads made. In the Sixties Ford threw in the towel and built a 427 inch overhead cam Hemi engine (not to be confused with the "semi-Hemi" 429 Ford) that had the valves opposed by 180 degrees.
Chevy lovers got their own Hemi head engine when So-Cal drag racer and manufacturer Nick Arias designed and produced Chevy-style cylinder heads with Hemispherical chambers that would bolt onto his version of the Chevy blocks.
But one problem remained. All of the mentioned
engine combinations make a lot of power using
a supercharger or fuel injection burning alcohol
or nitromethane, but when used as a gas-burning,
carbureted, Pro Stock style engines, they aren't
competitive with the wedge-headed engines. It's
been twenty years or longer since a true Hemi-headed,
gas-burning engine powered a competitive Pro
class car. In fact, the last competitive traditional
Hemi-headed Pro Stockers were those of John
Hagen, Reid Whisnant (photo above) and Bill
Dempsy in the early 1980's. The current Chrysler
"Hemi" Pro Stockers don't have a true hemispherical