There were 16 of the 1967 RPO L89 Corvettes manufactured by Chevrolet, thus establishing the 1967 L89 Corvette in good company in the list of the rarest of Corvettes ever produced. Regular Production Option (RPO) L89 was a standard option on the 1967 Corvette that turned it into the ultimate C2 road car.
The L89 aluminum head 427 motor was GM factory rated at the same horsepower of 435 HP as the L71 cast iron version. But it is believed that the L89 had an increase in horsepower over the L71. The L89 heads had bigger exhaust valves at 1.84 in. versus the 1.72 in. exhaust valves on the L71 cast iron heads. Although the L89 and L71 motors were basically the same other than the heads; the bigger exhaust valves had to guarantee more horsepower. With the L89 aluminum heads yielding a weight saving gain of approximately 75 pounds off the nose of the car, plus the performance increase; the 1967 L89 Corvette was in a league of its own.
The engine in the RPO L89 was known as the L71 427/435 HP Tri-Power engine. In standard spec, it offered 450 bhp, but the RPO L89 added $389.65 to the price and raised power by 25 bhp. Furthermore the aluminum heads saved considerable weight, so much so the engine was lighter than the cast-iron 327. Note that L89 option listed for $368.65 but had to be ordered with option L71 at its cost of $437.10, which gave a total of $805.75.
Although the L89 was not nearly as radical as the revered L88 performance, it was more streetable. The L88’s came with no radiator shrouds. The L89 at less compression and with a radiator shroud; allowed you to stop at a traffic light without the fear of it overheating. The L89 was equipped with the ever-popular tri-power carburetion, which combined with the unpainted aluminum heads; appeared ominous when one popped the hood open.