Cody’s C6 Z06: Father-Son Duo Builds Best Of Both Worlds

Being a GM development driver comes with a few perks. In addition to the privilege of getting flown around the world to test interesting new machines, one of the less obvious pros to this line of work is being able to cement a relationship with your father when he decides to turn his Corvette into a special sort of track toy.

Cody Bulkley’s education and career facilitated the development of his dad’s C6 Z06 — a project ten years in the making. His background has helped him from being swayed by forumthink, as the idea of a clubsport build isn’t always encouraged by the armchair authorities. Some claim that the best of both worlds just can’t be attained and, in actual fact, any attempt will result in something that performs poorly on street and track. Cody thought otherwise.

In his mind, a reasonably modern car can be versatile enough to drive three-hundred miles to a track, compete with caged cars, and drive home in relative comfort, but it’s not an easy balance to strike. It takes a special sort of patience and technical insight to arrive at this compromise.

During his five years in a dual bachelor’s program at the Oregon Institute of Technology, Cody joined the school’s FSAE program, which later led him towards a role in the performance end of the automotive industry. General Motors hired him as a chassis integration engineer and he joined the team that developed the C8 Corvette. Concurrently, his dad picked up the Z06 with the intention of turning it into a serious track toy. With all Cody had gleaned from his job, he had to get involved.

“The easy answer to building a track car is to throw a set of Penskes, a cage, and full aero at the car and call it a day, but we couldn’t do that. Dad drives the car to work regularly, so we had to make it more than a back-breaking trailered car.”

While that was a tall order with a relatively spartan and simplistic performance car, the C6 Z06 has good bones, and proved to be much more versatile than he had originally believed.

The first order of business, as his father requested, was increasing power, which was followed by the attendant challenges of cooling a hot-rodded powertrain. A big cam, a ported intake manifold, upgraded trunion rockers, bronze guides, race lifters, ported and polished heads, and long tube headers added another two hundred horsepower to the tally.

To enjoy some 700 horsepower on hot days, the father-son duo had to labor over the cooling package. After plenty of deliberation, the two installed a GSpeed dual oil cooler, Spal fans, a C&R radiator with the GSpeed C7 fan kit, and an LG Motorsports vented hood. Along with engine coolers, they added a GSpeed power steering cooler and a Turn One power steering pump.

The dual-wishbone setup needs little to make it work well with wide tires and a good deal of lateral load.

To keep the car civilized enough for stoplight-to-stoplight driving, they pulled a few OEM products from the Vette parts catalog, including a C6 ZR1’s torque tube, a C7 ZR1’s clutch and mated them to an RPM-built transmission, which has proven capable of handling the power.

Its 600 lb-ft of torque and 7,100-rpm redline would make a 4,000-pound vehicle feel frighteningly fast, but this Z06 weights in at 3,150 pounds without driver. Not many can outgun this car on straighter sections, but many modern cars could make better use of the power — at least before Cody went to work on the suspension.

The combination of stock suspension and big power left Cody with no leeway. Its sudden breakaway made it difficult to attack faster corners, and when the road surface varied much, it didn’t inspire confidence. Along with the optimized spring rates for their LG coilovers and the GM T1 bars at their softest settings, they installed a Wavetrac torsen-style differential. “That diff made all the difference. It made it possible to finesse the throttle. We found a second with that one modification alone, easily. All these touches have made it progressive in the power-down phase, and that’s why I’ve been able to find most of its time in the high-speed sections.”

Subtle aero mods helps this car slip under the radar while encouraging faith at higher speeds.

It has to be said that, despite its stockish silhouette, the aerodynamics have been massaged, though only a little. Nevertheless, the resulting improvement of the center of pressure helped improve the car’s performance in faster sections. “Originally, it was a little aero-loose,” Cody began, “but we moved its pivot point rearward with a rear wing, wickers, and a big front splitter for balance.”

Thankfully — and making the finer points of this process is due to Cody’s education — the improvement in stability didn’t come with any detriment to livability. “We’ve kept all the factory rubber to keep it semi-civilized,” Cody said.

“We had to replace the front and rear brakes with a set of AP Racing six and four-piston brakes, respectively, but they last a long time. OK, we have to pay the Corvette tax in tires, but we’re able to stretch a set of Supercar 3Rs through four or five weekends.”

That combination of moderate weight and mega power has produced lap times that modern supercars and a few full-on race cars might struggle to meet, as seen below:

Not to add insult to injury, but the current lap times don’t tell the whole story. Cody’s personal best at Laguna Seca was set with a failing clutch, and his best at Thunderhill was set on a 90-degree day. When all their stars align, the Corvette may run a couple seconds faster at the featured tracks.

And this very car was driven to and from the track. Cody’s dad even takes it on work trips to Washington State every blue moon, and it still hurts feelings. “As I said, it’s not easy to find that balance between street and track, but we’ve been able to compete with plenty of caged race cars in what is truly a street car. As we incrementally improve the car, we are aiming at setting several class records across West Coast time attack organizations,” Cody concluded.

I'd like to give a big thanks to Roger, Jamie, and Gary for helping me tear down and rebuild the car over the last decade. Couldn’t have done it without you guys.