Corvette ZR-1 - Staying on Top

Is the King of the Hill still on his throne? Considering the currentC6--a two-valve-per-cylinder, 6.0L small-block that pumps out 400hp--the 375-horse ZR-1 has some hill climbing to do. Owners like TonyDavila, who trains helicopter pilots in the military, know just what todo to keep their rides on top.

The buzzword is technology. GM uses it for its latest and greatestsmall-block, and so do ZR-1 owners today, but with a motive Tonyrevealed: "to preserve and constantly tweak to get every last ounce ofpower without taking away from its essence."

In other words, Tony will modify for more horsepower, but he'll go onlyso far. He won't alter the character of the exotic LT5, afour-valve-per-cylinder, dual-overhead-cam V-8. "There's nothing thatsounds like an LT5 at seven grand," he says, "nothing."

Tony's ZR-1 craving goes back to the car's inception. He wanted one whenthey came out in 1990. "I had an '85 Corvette," he says. "At that time,I couldn't afford a new ZR-1, [but] I still wanted one. Then 1998 rollsaround and it was affordable to me."

Once Tony had his dream ride, he confined LT5 mods to "little tweaks."Porting the upper intake and injector housings is popular. Ascomplicated as the internal valvetrain is, port-matching is an oldhot-rod trick that anyone can do at home in their spare time. The workis laborious and time-consuming, but the result is real horsepowerincreases. Tony guesses he picked up about 30 horses from port-matching,which consumed about 80 hours and saved him two grand in labor if he'dhired a shop.

ZR-1 owners are a proud lot. Their cars have a storied heritage ofrecords, like the 24-hour speed record, 175.885 mph, set March 1-2,1990, in Ft. Stockton, Texas, by Tommy Morrison and crew.

Morrison likewise supplies ZR-1 owners with inspiration in the form ofthe Snake Skinner, a one-off with a hopped-up LT5 that featuresweight-saving tricks like a carbon-fiber body, a plexiglass rear window,cloth seats, and a feature on Tony's black ZR-1: gills for the sidevents in the front fenders. "I wanted to make it my own without gettingaway too much from its roots," Tony says, "because everything I put onit I can take off. I didn't do anything I couldn't reverse if I had to."

Engine tweaking continued with a Doug Rippie chip, a set of Watsonheaders, and a K&N air filter. Tony says, "I dyno'd it at Aaron Scott'sat South Georgia Corvettes in March 2004. It pulled 452 horses at thecrank and 385 at the rear wheels." That's enough horsepower to remainking over all stock late-model Corvettes, including the new C6 and C5Z06. Tony figures the set of 3.90 gears he added "made the transmissionmore usable in the rpm where the engine operates."

We took these pictures at The Gathering last year at the NationalCorvette Museum. Rain on Saturday limited drag racing, but Tony managedto get in one run and (on street tires) clicked off a 12.60 at 113 mph."That was my first run, so I'm sure it could go quicker," he said.

Would any stock Corvette like to challenge the King of the Hill?