Buick Grand Sport 455 GSX Stage 1 455/455 1970 Coupe

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Grand Sport 455 GSX Stage 1 455/455 1970 Coupe





The 400 was replaced for 1970 with the 7.4 litre Buick V8, used in the GS 455. The base model V8 was rated 350 hp (260 kW) and 510 lb·ft (690 N·m) at 2800 rpm. In the optional Stage1 trim it was rated** 360 hp (268 kW) and 510 lb·ft (691 Nm) at a low 2800 rpm. As with all American engines produced prior to the 1972 model year, these were SAE gross ratings, which are generally significantly higher than SAE net ratings and are not indicative of what actual production engines produce in their "as installed" condition (with all engine accessories and full exhaust system in place). The fastest magazine test results from this period were obtained by MOTOR TREND Magazine, which managed to extract a 13.38 ET @ 105.5 MPH from their 3,810 pound GS Stage 1 coupe test car. Using Hale's Trap Speed formula, this result indicated actual "as installed" peak HP of approximately 360 SAE Net (ironically the same as its advertised Gross Figure, meaning this engine was very conservatively rated for that time period). The use of the larger sized 455 block created a maintenance problem by the exhaust manifolds being in too close proximity to the upper and lower A-arm bushings. Heat would literally melt the bushings after a relatively short period of time; rapid tire wear and front end alignment difficulties were the first sign of this common problem.

Coming correct with a gigantic 455 cid V8 and a Hurst four-speed, the GSX had all the grunt any self-respecting son of the seventies needed. Power figures are elusive and confusing. Officially, the factory quoted 360 hp @ 4,200 rpm. No doubt this was true, but what did the mill stonk at say 5,200 rpm? At least 400 horses, if not a bit more (415 to 425 hp). GM fudged the numbers because insurance companies at the time were charging huge draconian penalties premiums based on horsepower. The corporate wink, wink saved customers from insurance payments bigger than their car payments. Luckily insurance companies didn't care about torque, as it is hard to hide 510 lbs. ft. of the good stuff at a 2,800 rpm.

GSX / GSX Stage1 was the optional high performance package available on the GS 455 starting in 1970. The GSX ornamentation package was a $1,100 option on the GS455. The GSX was made to attract attention, and to help showroom traffic in an effort to increase sales. The GSX was Buick's answer to Pontiac's GTO Judge and Oldsmobile's 4-4-2 W-30. Buick advertised it as "A Brand New Brand Of Buick" and "Another 'Light Your Fire' Car From Buick". It was only available with the standard big block 455 engine or the optional Stage 1 engine the first year. It was not a very popular model, and only 678 GSXs were produced in 1970. Just 278 were equipped with the standard 455, a further 400 being equipped with the optional Stage 1 performance package. The performance of a GSX (or GS) Stage-1 is comparable to that of the HemiCuda, but in a much more luxurious car. This is partly due to the light weight of the 455 which is roughly 150 lb (68 kg) less than the 426 Hemi or Chevrolet 454. The engine's performance also relies on the tremendous torque this engine produces - 510 lb-ft (gross) at 2800 rpm. Production dropped in 1971 to only 124, and again to 44 in 1972. These numbers include the available 350-4 bbl option, the standard 455, and the Stage 1 engines.

In 1970, the GSX option was available in only two colors, Saturn Yellow and Apollo White (in 1971 and 1972 6 other colors were available for the GSX). All GSXs had the distinctive full body length black stripe that crossed over the standard equipment rear spoiler and was outlined in red pin stripes. A large area of the hood was also black with a hood mounted tachometer (Buick engineers disliked the hood tachometer because it was a Pontiac part) and black front spoiler. Also standard equipment were black bucket seats, floor shifter, wide oval tires, quick ratio steering and anti-sway bars. Some other options were automatic transmission or four speed manual.

After 1970, the 1971 and 1972 GSX became an option that was available on any Gran Sport.

The GSX and big-block V8 were dropped after 1974. In 1974, the GSX consisted of a trim package on Buick's small, X-bodied Apollo. Three engines were available on the 1974 GSX: the Chevrolet supplied 250 6-cyl.,and two Buick engines:the 350 2 barrel and 350 4 barrel versions.

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