The Mopar Hemi Engine has become a Legend in the American Muscle Car Industry making a Mark in the NHRA Drag Racing sport since 1965.
Starting with the 392 Hemi Engine in 1951, The Chrysler Hemi engines, known by the trademark Hemi, are a series of I6 and V8 engines built by Chrysler with hemispherical combustion chambers. Three different types of Hemi engines have been built by Chrysler for automobiles: the first (known as the Chrysler FirePower engine) from 1951 to 1958, the second from 1964 to 1971, and the third beginning in 2003. Although Chrysler is most identified with the use of "Hemi" as a marketing term, many other auto manufacturers have incorporated similar designs.
The street version was created with a lower compression ratio (from 12.5 to 10.25:1), milder valve timing, different intake and exhaust manifolds, and cast iron heads, instead of aluminum, for long term reliability. During its eight year production life, the street 426 Hemi saw updated camshafts (more duration was added in 1968, and a hydraulic bumpstick was used beginning in 1970) but few other changes. Chrysler kept the engine’s horsepower and torque ratings, 425 hp at 5000 rpm and 490 foot-pounds of torque at 4000 rpm, when ratings switched from gross to net. Four bolt mains were standard on every 426 Hemi, street or race.
A new breed of 426 cubic inch V-8s was being built with the legendary “Hemi” heads, said to be cranking out a routine 750 horsepower. The opening shot was set for the 1964 NASCAR season opener at Daytona on February 23, 1964. 426 Hemi with Mike Buckel and Forrest PitcockIt was a painful secret that to hold, that the engine blocks for that race had been poured into molds in December 1963. After careful assembly at Chrysler's engine lab in Highland Park, these prototype engines were run out at full power. Disaster and disappointment prevailed. The blocks developed several cracks on the thrust side of the right hand bank. Engineers scrambled to find a solution. It didn't take long to figure out that with a whole lot of that sort of horsepower, thicker walls was the only means to solve the problem. It sounds simple, but scraping away the cooling core to increase the wall thickness resulted in not being able to get a correct bore casting — even though the casting was being done by one of the best foundries in the USA, in Indianapolis.
The rules in NHRA Super Stock for the new year precluded the use of lightweight body materials, meaning the fabled aluminum fenders would be a thing of the past. Instead, the cars were made of steel, albeit stamped from a gauge material lighter than what production models received. The Dodge Coronet and Plymouth Belvedere sedans were further lightened with stripped-down interiors and modified for better weight transfer by moving the battery to the trunk and reducing the wheelbase (down to 115 inches) by reworking the rear leaf-spring mountings. In the end, the car crossed the scales at 3,408 pounds-not bad for a B-Body. Once on the track, the machines proved the factory had made a good investment. They took victories at many events, set records on a regular basis, and Bill Jenkins (yes, the grumpy one) won the NHRA World Championship in a Plymouth called the Black Arrow. The era of Hemi dominance in the upper tier Stock classes had been cemented.
Mopar or No Car
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