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Pontiac began as an adjunct to the Oakland division of the General Motors line of automobiles in 1926. Pontiac successfully competed against more-expensive four-cylinder models with their inline flathead six-cylinder engines. After outselling Oakland, Pontiac became the sole survivor of the two by 1932. In addition to the inline 6, Pontiac also had an inline 8 by 1933. These two engines were used through 1954, when Pontiac unveiled its V8 in 1955. From 1955 to 1981 the Pontiac Division of General Motors manufactured its own engines, distinct from Buick, Cadillac, Chevrolet, or Oldsmobile. Displacement began at 287 cu in and grew as large as 455 cu.in. (7.5 L) by 1970. Pontiac engines were used in its U.S.-market cars; Canadian-built Pontiac automobiles generally used Chevrolet engines. From 1955 through 1959, the Pontiac V8 was also used in some GMC pick-up trucks. ==History== The development of Pontiac's OHV V8 dates back to 1946, when engineers began considering new engine designs for postwar cars. Despite these experiments, the division's conservative management saw no immediate need to replace the Pontiac Straight-8 engine, which had served well since 1933. When Robert Critchfield took over as general manager in 1952, however, he launched an ambitious plan to move Pontiac into the upscale, mid-range market segment occupied by Oldsmobile, and that demanded V8 power. The development of the new engine was fast-tracked, but since its relatively late development let it take advantage of the experience gained in the Oldsmobile V8 engine and Cadillac V8 engine, it was remarkably free of teething problems. The main innovation of the Pontiac engine was the stamped rocker-arm system, which had been devised by Pontiac engineer Clayton Leach in 1948. At the request of Ed Cole, general manager of Chevrolet, the layout was also used by the Chevrolet V8 released in 1955, an exception to the customary GM policy of allowing a division one year of exclusive use of an internally developed advance. Federal emissions standards and the drive towards "corporate" engines shared among all GM divisions led to the progressive demise of the Pontiac V8 through the late 1970s. The last "true" Pontiac V8's, a 265 cu in and a 301 cu in, ended production in 1981. Pontiac also used the Oakland V8 engine in 1932 only. During 1951–1952, Pontiac had 23 1953 model production prototypes running tests on the GM proving grounds. These 23 cars were equipped with the new 287 V8 engine. Pontiac planned to produce the 1953 models with the V8, but Buick and Oldsmobile feared a sizeable loss in customers, if they had to compete with Pontiac having a new V8 engine. After hearing from Buick and Oldsmobile, GM's board of directors ordered Pontiac to delay the V8 introduction until 1955. Pontiac's V8 development that started in 1946 was a 269-cubic-inch L-head design. The 287 cu in overhead design started in 1949. Pontiac engineers tested their 269 V8 in 1949 or 1950 against a downsized Olds rocket V8 overhead engine. The Olds engine was a 303 cu in, Pontiac reduced the size to 270 cu in for testing against the 269 engine. The test results showed Pontiac that a L head engine couldn't compete with the overhead engines. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Pontiac V8 engine」の詳細全文を読む スポンサード リンク
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