I came across two interesting pieces of information regarding the development of the modern Hemi engine. Kind of cool that they would pick the brain of one of the original 426 engineers. Thought you guys would be interested. Tom Hoover, one of the engineers responsible for the 426 Hemi, told Hot Rod that he had discussed the Elephant Engine's design with new-Hemi engineers. At least three of his suggestions - raising the camshaft (to shorten pushrods, reducing valve train inertia and allowing simpler exhaust rocker arms), using twin spark plugs, and adding squish area (to make light load/low speed efficiency better and reduce emissions) were immediately adopted. In the 1980s Japanese manufacturers reduced unburned hydrocarbons by placing spark plugs either in the exhaust pipe (which fired with every piston ignition) or in the exhaust manifold (which fired each time their corresponding cylinder fired). Chrysler morphed this idea to include dual fired plugs on each cylinder, which allows the firing to take place closer to top dead center, and then again when the piston is on the back side of the power stroke.
That is some cool info. I bet Mr. Hoover is pretty proud of his Elephant engines both past & present.
