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.

Thomas' Corvette: In Good Company

Finishing out his senior year of high school, Thomas DiGioacchino listened to a friend’s suggestion and scrounged the money together for his first track day. Crap tires, decent weather, and a near-stock Mustang GT were all he needed to find that thing that’s been steering his life for the last five years.

Thomas decided to pursue the mechanical side of things and enrolled in Ranken Technical College’s High Performance Technology course with a focus on Chevrolet LS engine design.

That emphasis allowed Thomas to build a motor for a car he hadn’t yet bought. It began with an iron-block LQ motor and LS1 heads, and as the LQ block only displaced 5.3 liters, he bored and honed it out to 5.7 liters to fit the LS1 head. With forged pistons and rods, oil pan baffles, and the other pieces that made it a 500-horsepower workhorse, he unknowingly set the tone for the rest of this build.

The car itself came next. During his final year at Ranken, he found himself a base 2002 Corvette within his price range and tucked it away in his side yard until graduation, when he loaded up his truck with his furniture, his motor, and began his drive from Missouri to his hometown.

Back in San Mateo, he reached out to his then-limited network for car parts and, with some luck, gainful employment as well. As he’d relied on Elite Performance to direct him towards a few bolt-ons for his Mustang, they were the natural resource to consult. One day, while speaking to Elite’s Melody Cannizzaro about getting his Corvette aligned, she provided up with a job opportunity. He didn’t have to think twice.

Working with Elite gave him access to one longtime customer who happened to be offloading some go-fast bits from their recent Corvette build. Thomas was able to grab a set of Titan 7 T-S5 wheels for peanuts, and then came big brakes, bushings, and a bucket seat. Soon, the plans for keeping the Corvette tame and civilized went out the window.

Wisely, he went for safety equipment next, and decided that this car would only help him become a truly quick driver if it was reliable first and fast second. “I knew that seat time would be the priority if I was going to run with guys like Gary Yeung,” he said.

That said, it would be silly not to make use of the big motor sitting in his parent’s backyard. Soon, it found a new home in the Corvette’s engine bay, and Thomas took the half-built C5 to its first track day, where it ran without a hiccup. It ran well the second day, too, as well as the third. Clearly, he’d paid attention in class.

Aside from the minor repairs any twenty-year-old car needs, it was the epitome of dependable. His focus was on learning to drive the car better, but, to his credit, a C5 on stock suspension does leave a lot to be desired. It would lean excessively, and under trail braking, it had a habit of snap-oversteering.

After several months of saving, Thomas bought a used set of JRZ two-ways. While he was at it, he pulled and refreshed the entire drivetrain, then upgraded the springs and clutch packs in the OE LSD. Those modifications made the Corvette much more progressive at the limit, regardless of whatever cheap tires he happened to be running.

When he found the time to fine-tune the suspension, he increased the rake to increase rotation at corner entry. A square 295-35/18 setup was the cost-conscious tire option, and he stretched every set until the cords showed. Still, the car was mostly neutral with a hint of understeer in the faster stuff thanks in part to his APR GTC-300 wing.

As his confidence grew, he started to recognize that driving around on worn rubber was no longer the training tool it had been, so he sprung for a set of AR-1s and turned his first sub-two-minute lap at Buttonwillow 13CW. “I had to fight it the whole way around, but I got 1:58. A sloppy 1:58, but still,” he said.

Good tires helped, as did having a hare to chase. With Gary Wong driving his S2000 off into the distance, Thomas was able to see where he could push harder than he believed was possible. It’s a huge help having an experienced driver luring your outside your comfort zone.

Logging that first milestone lap gave him the confidence to try the Speed SF Challenge the next weekend at Thunderhill’s five-mile configuration. He did his homework and studied several record laps, focusing on curb usage. With Gary Yeung giving him some basic feedback the day of, Thomas saw his lap times fall by as much as four seconds. In the end, he was able to clinch third place in S2 — just half a second behind Kevin Schweigert in his BMW M2.

That success turned Thomas into a sponge. His subsequent lapping days have been spent studying data and having the experienced drivers like Joe McGuigan critiquing his onboard videos. “Joe’s been a huge help; giving me pointers on which gears to use so I can put the power down more easily.” The result of this traction-conscious approach to driving is evident in the footage below:

He’s also benefited from picking a short list of prime parts. In fact, he’s never bent his Titan 7 wheels or broken any suspension parts, despite hammering curbs and dropping wheels regularly. Maybe it has something to do with emphasizing robustness with this build—a tip he picked up from his mentor, Gary Yeung.

‘I’ve learned a decade’s worth of motorsports knowledge in the last two years. Everyone’s been so supportive, and I owe my progress to all of them. They’ve pushed me to improve as a driver and a builder—especially Gary. Watching him work inspired me to raise my game, and I think it shows. My Corvette’s overbuilt, so I can push it all day. Like Mango, my Corvette is a workhorse that’s made it possible to attend almost every Speed SF event in the last two years. All I do now is change the fluids and try to find out where I can go faster.”

Parts

• JRZ motorsport coilover conversion

• Titan 7 T-S5 wheels 18x10.5”

• Trackspec hood vents

• Dewitts radiator

• Spal fans

• Improved Racing oil cooler

• Improved Racing oil pan baffles

• Prothane polyurethane bushings

• APR GTC-300 wing

• APR splitter