The return of the ZR1 for 2009 heralded the revival of a fabled Corvette moniker. Like its C4 progenitor, the new Z boasts a unique engine and an emphasis on flat-out speed. But with its world-beating performance and aggressive appearance, this over-the-top C6 has arguably committed an act of lese majeste by stealing some of the grandeur from its older sibling.
Rather than brooding like a Danish prince, Corey Henderson's '91 Corvette ZR-1 has risen to the challenge posed by the new king. Henderson is the owner of Henderson Performance Technologies, a performance shop in New Braunfels, Texas, and he's recognized as something of a C4 ZR-1 guru. Using the resources at hand and a passion for Corvette performance, he built his ostensibly humble car to have the power of a vicious tyrant.
Owning a ZR-1 was a longtime ambition that Henderson assumed he would not fulfill. "I had always loved the ZR-1 as a kid but knew I would never be able to afford one," he says. As he grew financially sound with age, Henderson was able to realize his dream and purchase his '91 Z in 1997. "Of course, the realization at that point was that though I now had a ZR-1, I wouldn't be able to afford to modify it, as the cost was extremely prohibitive." But once again Henderson proved himself wrong, this time by augmenting the already-prodigious power of his mighty king.
Much like the contemporary LS9, the C4 ZR-1's Lotus-designed LT5 engine is a unique specimen among Corvette powerplants. The sophisticated motor features an all-aluminum build and a dual-overhead-camshaft valvetrain. While it was a low-production engine, many of its advances were carried over into the Northstar and LS1 mills. "All the LS-based engine owners out there should take a minute to say, 'Thank you, LT5,'" Henderson says with a smile. These motors are known for their naturally aspirated power potential, and Henderson's is no exception.
Henderson procured a '90 LT5 from a junkyard and set out to build it into a 368-cube screamer. "After about a year of collecting parts, I put her together and swapped out the engine," he says. A rotating assembly comprising the stock crank, Eagle rods, and JE forged pistons was used, bumping compression to a stratospheric 12.25:1. The original cylinder heads were ported and treated to Jeal EA22 cams on the intake side and exhaust cams from the 405hp '93-'95 LT5. The stock intake manifold and throttle body were then ported for improved breathing ability.
The motor exhales through a set of Geoff Jeal headers with outsized 2-inch primaries and 3-inch collectors. The car also features a B&B 3-inch dual exhaust system with a cross-pipe exhaust system. To maximize the benefit of the performance parts, Henderson tuned the car himself on his shop's in-house dyno.
After a nearly three-year build process, the ZR-1 was completed in 1999. The end result of Henderson's tinkering is an impressive 502 hp and 446 lb-ft torque at the wheels. This royal might propels the car through the quarter-mile in 11.42 seconds at 125.8 mph. But despite its imposing power and extensive modifications, Henderson's ZR-1 has been a paragon of reliability. "For the past 10 years, I've done nothing but change the oil and spark plugs in the car," he says. "You can't ask for much more than that."