Invite That Hemi to the Ball.(News)

Byline: Kevin Wilson

Since we've got the Chrysler 300C on the cover, let's talk about this Hemi thing. It's more than 50 years since Chrysler invented the trademark, one at least as powerful as the technology. The word is just shorthand for a hemispherical (that is, half a sphere) combustion chamber. Like many trademarks, it is frequently misunderstood and the public often misapplies the word to describe any Mopar performance engine. Since it has been used in all uppercase letters (HEMI), some even think it is an acronym. It's not.

Chrysler didn't invent the half-a-ball chamber; it can be found in engines back to the nascent days of internal combustion. Its advantage has to do with the ratio of surface area to volume and therefore thermal efficiency, and in that it allows the valves to be arranged to provide cross flow, from intake on one side to exhaust directly opposite. Chambers like this contributed to the Stutz and Duesenberg reputations for high performance before Walter P. even founded Chrysler.

Chrysler did some research and development on cylinder heads with (small h) hemi chambers for World War II tank and aircraft engines, but didn't get to apply it until the civilian Firepower V8 of 1951, a big H trademark Hemi of 331 cubic inches rated at 180 hp. Its potential is evident when we see that the famous Chrysler C-300 of 1955 was named for its horsepower rating. Yet, after appearing in displacements from 276 cid to 392 cid and under various names (DeSoto Fireflite, Dodge Red Ram), the Hemi was gone from the corporate car range in '59. A hemispherical chamber was (is) expensive to machine, and lighter, more efficient new designs were coming. In 1960 the 413-cid V8 with its wedge-shaped chamber was rated at 400 hp in the 300F. Got a 383, 413 or 440 in that Mopar? It may have a lot of muscle, but it doesn't have a Hemi (look it up at thehemi.com or in Robert Genat's book Hemi: The Ultimate American V8).

Wedges sufficed until Chrysler revived the Hemi in a handful of '64s, primarily for ...