Generation 2 - 1970-1981

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The Second Generation appeared for the 1970 model year as a mid-year introduction on February 26, 1970 — but was officially designated by Pontiac as a 1970 model, not a 1970-1/2 as many sources have reported through the years. Replacing the "Coke bottle" styling was a more "swoopy" body style, with the top of the rear window line going almost straight down to the lip of the trunk lid — a look that was to epitomize F-body styling for the longest period during the Firebird's lifetime. The new design was initially characterized with a large C-pillar, until 1975 when the rear window was enlarged.

There were two Ram Air 400 engines for 1970: the Ram Air III (335 hp, 366 hp in GTO) and the Ram Air IV (345 hp, 370 hp in GTO) which were carried over from 1969. A distinctive, slant-nose facelift occurred in 1977, redone somewhat in 1979. From 1977 to 1981, the Firebird used four square headlamps, while the Camaro continued to retain the two round headlights that had previously been shared by both Second Generation designs.

The 455 engine available in the Second Generation Firebird Trans Am was arguably the last high-performance engine of the original muscle car generation. The 455 engine first made its appearance in 1971 as the 455-HO. In 1973 and 1974, a special version of the 455, called the SD-455, was offered. The SD-455 utilized leftover components from Pontiac's 366 NASCAR engine, and was built as a full-bore racing engine that produced over 540 hp; the engine was subsequently "toned down" to appease the EPA and to meet GM's own strict power policy, which at the time required that no GM vehicle exceed 300 hp. As a result, the PMD engineers listed the SD-455 at 290 hp, but in reality it was producing, in final form, 371 hp SAE NET (or approximately 440 gross horsepower). What made this engine even more appealing was the ease with which it could be returned to its 500+ horsepower form. The SD-455 is often considered the last of the true muscle car engines and, by many, considered to be the most powerful factory Pontiac engine ever produced. Pontiac offered the 455 for a few more years, but tightening restrictions on vehicle emissions guaranteed its demise. Thus, the 1976 Trans Am was the last of the "Big Cube Birds," with only 7,100 units produced with the 455 engine.

In 1974, Pontiac offered an inline-6, a 185 hp 350 in³ V8, and 175 to 225 hp 400 in³ V8 engines. The 455 produced 215 and 250 hp while the SD-455 produced 290 hp. The 400, 455, and SD-455 engines were offered in the Trans Am during 1974, but the 400 and 455 engines were the only other options in the 1975 and 1976 models. In 1976, Pontiac celebrated their 50th Anniversary, and a special edition of the Trans Am was released. Painted in black with gold accents, this was the first anniversary Trans Am package and the first production Black and Gold special edition. In 1977, Pontiac offered the T/A 6.6 Litre 400 (option W72) rated at 200 hp, as opposed to the regular 6.6 Litre 400 (option L78) rated at 180 hp. In addition, California and high altitude cars received the Olds 403 engine, which offered a slightly higher compression ratio and a more usable torque band than the Pontiac engines of 1977.

Beginning in 1978, Pontiac engineers reversed years of declining power by raising the compression ratio in the Pontiac 400 through the installation of different cylinder heads with smaller combustions chambers (taken from the Pontiac 350). This increased power by 10% for a total of 220 during the 1978-79 model years. The 400/403 options remained available until 1979, when the 400 in³ engines were only available in the 4-speed transmission Trans Ams and Formulas (the engines had actually been stockpiled from 1978, when PMD had cut production of the engine). 1979 marked the 10th Anniversary of the Trans Am, and a special anniversary package was made available: silver paint with a silver leather interior. The 10th Anniversary cars also featured a special Firebird hood decal, which extended off of the hood and onto the front fenders. In 1979 Pontiac sold 116,535 Trans Ams which still holds the record to this day. In 1980, due to ever-increasing emissions restrictions, Pontiac dropped all of its large displacement engines.

1980 therefore saw the biggest engine changes for the Trans Am. The 301, offered in 1979 as a credit option, was now the standard engine. Options included a turbocharged 301 or the Chevrolet 305 small block. In the final year of the Second Generation Firebirds (1981), Trans Am still used the same engines as it had in the previous model year, with the only change being the addition of a new electronic carburation system.

- Courtesy of Wikipedia