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Second Generation (1970-1981) During the 70's the era of the muscle car is going to
start fading away, mainly because of government regulations, the need
for fuel conservation, and growing insurance premiums for high horsepower
cars. But the muscle car spirit would never die in the Trans Am.
For the 1970 TA the power plant would be a 345 HP base 400 and with the Optional Ram Air IV the rating would be 370. 1971 would be the debut of the 455, but the insurance companies were getting there way as high horsepower is fading away. The 455's compression ratio in '71 would be be a low 8.4:1 compared to the 10.5:1 of the 1970 400. The horsepower was still there though coming in at 335 at 4800 RPM. Unfortunatly the 455 never had a chance to truely shine. The bigger 455 will never have a stock rating higher than the smaller 400. It came about in an era where high horsepower was becoming a bad thing due to the times. But a 455 can still be built nicely to make some great power. The H.O. in 455 H.O. wasn't as high output as it used to be or could be, as 1972 roled around. The rating dropped down to 300. Also the functional shaker hood was no longer functional starting in 1973 because of noise standards. With more emissions regulations, the 455 was going down, so to speak. The horsepower rating would drop down to only 250. But there is a bright spot in 1973 for the Trans Am, it was called the Super Duty. Back for a short breath was an aggressive cam shaft profile and cylinder heads that had a design that got them around the economy friendly ones they were supposed to be using. The 1973 S.D. Trans Am was capable of doing the 1/4 mile in 13.54 seconds at 104.29 miles per hour. Pontiac stood alone in 1973 as the mustang got big with the best engine being a 248 HP 351. Elsewhere in GM the Z28's best was a 245 HP less refined Corvette 350. The S.D. was king at 310 net HP early on, then 290 net with the more aggressive cam being eliminated. In 1974 the Super Duty 455 was back rated at 250 HP and 380 lb/ft of tourque - not a super as '73 -, the 400 was back rated at 225 Hp and 330 lb/ft of tourque, as well as the huge hood birds. And besides the 'Vette the Trans Am stood all alone. The Z28 would take a couple years off from production, and the Mustang was now based on the Pinto with only a 2.8 Liter V-6 as the top engine that year. But the real muscle car glory days are pretty much over. High horsepower is becoming a negative word for auto manufactures. Time to say see ya later to the 455 in 1975, but it seems that half way through the year pontiac decided to offer them again rated at 200 HP @3500 rpm. What a waste of cubic inches. And the low numbers there showed on the strip, the '75 455 took over 16 seconds to cover the same ground as the '73 SD-455 coverd in 13.5. The base 400 was only rated at 185 HP, reaching the power peak at 3600 rpm. With all the engine downgrades, at least the Trans Am is surviving. In 1976, the 400 and 455 were pretty much unchanged from the '75 motors, and black was now an offered color for the TA. 1977 was the year of the bandit cars. The restyled '77 Trans Am was Burt Reynolds' ride in "Smokey and the Bandit," giving the popularity of the TA a boost. Gone for good now was the 455, and now available was an Oldsmobile 403 engine. The base 400 was rated at 180 HP @ 3600 rpm and 325 lb/ft of torque @ 1600 rpm. A low 7.6:1 compression ratio was still the same from '76. The 403's ratings were 185 HP @ 3600 rpm, and 320 lb/ft of tourque @ 2200 rpm. The 403's compression was higher than the base 400's at 8.0:1. The higher end 400 was rated at 200 HP and had an 8.1:1 compression ratio. Although the looks of the TA were mostly the same as '77, horsepower was starting to be a good thing again. The high end 400 was now rated at 220 HP @ 4000 rpm and 320 lb/ft of torque @ 2800 rpm. The 185 HP Olds 403 was still an option, and the base 400 was still rated at 180 HP. 1979 was the last year of the big motors, and the first year a small engine (301) was offered. The Olds 403 was the base engine and the 220 HP Pontiac 400 was still available (only available with a 4-speed.) The little 301 was rated at 150 HP @ 4000 rpm and 240 lb/ft of torque @ 2400 rpm. Even with the 400 the Trans Am was still a 15+ second 1/4 mile car like the '78, but with higher gearing had a fasted trap speed (96.6 mph.) 1980 and 1981 the TA would go into production with either the 301 engine or the chevy 305 (LG4) which would see production in the 3rd generation 'birds. A bright spot may be the optional turbo 301. But the 400 is gone for good. And any high horspower numbers won't be back again for a while.
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