If it weren't for the Michelin Pilots and leather interior, Mike Lowry's '02 Z06, with its C5-R styling cues, could easily be mistaken for a GTS competitor in the paddock. Then again, a set of slicks and a five-point harness would fix that. To the enthusiastic, 50-year-old Texas owner, that's the point. "I wanted a car that would be 'out there;' something that would be the ultimate streetcar for a few years to come," Lowry says.
A quick check of the patriotically-painted Vette's specs certainly points to a high-water mark in street-legal performance: A 641hp, 7.0L Gen. III engine, T1 road racing suspension, 15-inch brakes with six-piston rotors up front, custom center-lock hubs, 18- and 19-inch wheels, and Specter Werkes/Sports GTR-inspired bodywork. And those are just the basics.
"Yes, the project got a little out of hand," admits Lowry, who went more than 14 months without setting eyes on his Vette during its construction. "I drove the car for about two months and put 329 miles on it before deciding to do something extreme to it. That was the last I saw of it for more than a year." The virgin Z06 left Texas for Arizona, where Extreme Motorsports performed the T1 suspension upgrades, including the road race-spec stabilizer bars and bushings. They also were scheduled to drop in a custom, 585-horse Katech-built engine, but Lowry's conversations with the engine builders put a halt to the new motor just as it was being lowered into the empty engine bay. "I got to talking with the folks at Katech and we decided to go with something wilder," he says.
That "something wilder" was a C5-R aluminum block with 4.125-inch bores, combined with a Moldex forged steel, 4.000-inch crank, resulting in 427 cubic-inches. The C5-R block is a different casting than production-style LS1 blocks. Revised coolant passages and a modular cylinder bank design permits overboring options unavailable to the standard LS1-type Gen. III block. Lowry's engine also boasts 6.000-inch. Carillo rods pinned to custom forged pistons. Katech, a company with integral ties to Corvette's racing program, was reluctant to divulge all the details of Lowry's unique combination, but we were able to pry out of them that the pistons deliver a 12.21:1 compression ratio. They also told us the cam is a solid roller, but were mum about its lobe profiles. Heck, they wouldn't even divulge the diameter of the throttle body.
There are lots of other custom parts attached to the engine, including the headers, fabricated sheetmetal intake manifold, and custom C5-R-logo valve covers (requiring the relocation of the ignition coil packs). Under those snazzy valve covers is a set of artfully sculpted C5-R cylinder heads, the inner contours of which are-you guessed it-as secret as Bill Gates' ATM card PIN. We know this: They've been ported, have 2.180/1.625 valves, and were expensive. Really expensive. Really, really expensive. We know how much they cost, but were asked not to publish it. Here's a hint: Lowry spent more on the heads than some people spend on, say, a brand-new car. In the understatement of the year, Lowry admits, "Katech did a lot of work to them."
And though it wasn't cheap, Katech's work paid off. On the dyno, the engine peaked at 641hp and 590 lb-ft of torque. "I can't say enough about how great Katech was in putting together this engine," says Lowry.