Every generation of Corvette has been equally comfortable on the street and on the racetrack. From the early C1 racers to the contemporary Corvette Racing Team juggernaut, Chevy's performance flagship has a storied motorsports history spanning more than a half-century. Visit any open-track event today, and you're likely to find both late-model and vintage Vettes tearing up the tarmac.
Don Ondrejcak of Clearwater, Florida, is no stranger to high-speed motoring. A lifelong hot-rod and motorcycle devotee, he has owned multiple musclecars and even a 500hp Porsche 930 Turbo. But despite his longtime involvement in the hobby, Ondrejcak reached a point several years ago at which he seriously considered exiting the performance scene for good. "I had been very busy with my business and decided to sell everything but my daily drivers," he says.
Shortly after selling his last numbers-matching '69 Camaro Z28, Ondrejcak spotted an unadulterated, low-mileage '03 Corvette Z06 on a dealer lot. As he tells it, "I had never been a big fan of the C5 Corvette, but after I testdrove it, I fell in love with it!" Wanting to introduce his 17-year-old son Don Jr. to the hot-rod hobby, he purchased the car the next day. After getting hooked on the C5, the father-son team set out to build an open-track monster.
When building the car's LS6 engine, Ondrejcak shunned forced induction in favor of old-school, naturally aspirated muscle. Accordingly, all modifications were undertaken with a pragmatic approach that eschewed flash in favor of reliable results. Every upgrade was thoroughly researched using the Corvette Forum and other Web sites. Although he was new to LS engines, Ondrejcak overcame the idiosyncrasies of the LS6 and found it to be similar to previous small-block Chevys, albeit with better build quality.
On top of the internally stock block reside a pair of Texas Speed & Performance Stage 2.5 ported cylinder heads fitted with stainless steel valves, PRC Gold dual valvesprings, Viton oil seals, and titanium retainers. The Texas Speed Magic Stick V.3 camshaft features 237/242 degrees of duration, 0.603/0.609-inch lift ratings, and a 114-degree lobe-separation angle. The rest of the valvetrain comprises GM Performance Parts Cadillac CTS-V roller lifters, TSP hardened pushrods, and an LS2 timing chain with a GMPP damper.
Meeting the rapacious air needs are a Vengeance-ported FAST 90mm intake combined with a TPIS 90mm throttle body with coolant bypass. The induction system includes a Raptor XXL air filter, smooth intake couplers, and a Z06 Shop high-flow air bridge. Ondrejcak also designed and fabricated an air opening in the front license-plate frame using stainless steel mesh.
The Z's gluttonous fuel demands are met with Comtec Performance fuel rails, FAST 36-lb/hr fuel injectors, and a Racetronix fuel-pump-harness upgrade. The ignition system is enhanced by NGK TR55IX iridium spark plugs, Granatelli wires, and DEI plug-boot booties. PCM tuning was left to Tampa tuner Jeremy Formato.
As it blasts through the gears around the track, the Z performs an aria ranging from guttural lows to a piercing high-rev contralto. The exhaust system begins with stainless steel Dynatech 1 3/4-inch long-tube headers mounted with heavy-duty ARP header studs. These expel gases through either high-flow cats or off-road bypass pipes and into a 2 1/4-inch cross-pipe before exiting through a Borla Stinger after-cat system.
Ondrejcak's hands-on approach goes far beyond the level of involvement of the average shade-tree mechanic. Working on a lift in his garage, he and his son performed all of the car's customization work, excluding the paint and tune. He even tried his hand at fabricating and designed a custom catch-can system for the engine. The sum of Ondrejcak's mechanical meddling is an impressive 510 hp and 400 lb-ft torque at the wheels.