1971 Corvette ZR2 with LS6 big-block engine. All photos from www.barrett-jackson.com

Chevrolet peaked the musclecar craze in 1971 when they offered the ZR2 Corvette package to the market. Featuring the LS6 engine RPO, a 454-cubic inch cast-iron block with aluminum heads, that produced 425-horsepower. This was the most powerful engine offered by Chevrolet in 1971, and this was the only year that it was offered in the Corvette in the ZR2 package.

The LS6 with a four-speed manual transmission and a 3.36:1 limited slip differential was said to have ran from 0 to 60 in 5.3 seconds. Only 188 of the 21,801 Corvettes made in 1971 were equipped with the Z06 engine. Only 12 were manufactured with the ZR2 package, making it rarer than even the L88 Corvettes. The one year production package is the rarest big-block Corvette ever built, holding a special place in Chevrolet’s history.

LS6 454i big-block Chevy.

The LS6 engine’s power is the result of a 4-bolt main bottom end, forged crank, along with forged connecting rods and pistons topped with aluminum cylinder heads. The ZR2 package added a transistorized ignition, a high-capacity aluminum radiator, a Muncie M22 Rock Crusher close ratio 4-speed, heavy duty power brakes, and special springs, shock absorbers, and front and rear sway bars.

The ZR2 was the big-block equivalent of the ZR1 small-block package. Like the ZR1, the ZR2 was not manufactured with a radio, air conditioning, or a fan shroud.

Built for ultimate performance in an age when GM’s performance hold on the industry was slipping, the limited number of these cars in the production run make it a Corvette collector’s ultimate trophy car.