Divine intervention. Some think that’s what the lift-prone C3 convertible needs to go 250 mph without turning into an unguided missile.
Duane McKinney, an 83-year-old Bonneville Salt Flats racer with a record-holding ’68 hardtop, roadster begs to differ. He says all it takes is 1,250 horsepower, half a ton of ballast, good course conditions and four decades of land-speed-racing experience.
For almost 40 years, McKinney’s Corvette has been setting Bonneville records. His team, whose members also include wife Suzanne and son David, races the blue roadster in the Southern California Timing Association’s (SCTA) Blown Grand Touring (BGT) category. The class requires stock bodywork—no rear wings, no big air dams and no altered panels, other than the hood. Remarkably for a car of its vintage, Sundowner holds records in the B-, C- and D/BGT categories.
People take cars to Bonneville for one reason: to go fast in a straight line. The first record was set there 100 years ago, but it wasn’t until the early 1930s that the Flats, located around 100 miles west of Salt Lake City, Utah, became a popular venue for speed-record attempts.
At the same time, about a thousand miles to the southwest, on the dry lake beds of the Mojave Desert outside Los Angeles, racers were starting to build what would become known as “hot rods.” After the Second World War, the racers returned, but as speeds increased and three of the four lakes were taken over by Edwards Air Force Base, these early hot-rodders looked to Bonneville.
Not only has Duane McKinney raced a Corvette at the Flats since 1975, he’s one of only a few active SCTA racers who were there at the beginning. The first Bonneville Speed Week was held in August, 1949. McKinney, then 17, and his brother, Bob, 22, drove Bob’s ’32 Ford from LA to hang out famed hot-rodder Ak Miller, who soon talked Bob into entering. The first McKinney to run at Bonneville went 104 mph—a bit short of a record, but not bad for a full-fendered roadster and a memorable experience for the two young men.
Duane did not return to the salt until 1969, but he’s been a regular there ever since. In 1975 he and racing pal Bob Kehoe paired up for a run at Bonneville and decided to use a Corvette for the effort. That February they bought a ’68 convertible off a lot in the LA suburb of Downey. An ensuing crash program had the team ready for Speed Week. The SCTA assigned them the number 42, and they nicknamed the car “Sundowner” after the best time of day to run at the Flats.
Kehoe and McKinney ran in D/GT in ’75 and ’76 but didn’t achieve much aside from grenading a few 302-inch engines. Then, in 1977, McKinney drove Sundowner, now powered by a Hilborn-injected 350, to its first record: 183 mph in C/GT.
In 1979 Gale Banks, whose specialty at the time was high-performance marine engines, took an interest in the car. Out came the 350 and in went a normally aspirated 430-inch big-block with an innovative air-to-carbon-dioxide charge-air cooler. That summer the Kehoe, McKinney and Banks Sundowner set a B/GT record of 210.762 mph, making it the fastest single-four-barrel Corvette at the event by a significant margin.
Three years later, at the 1982 Speed Week, the big-block Sundowner was back, this time packing two turbochargers, two four-barrels and another Banks first, an air-to-ice-water charge-air cooler. That combination made 850 hp and enabled the 42 car to smash the AA/GT (later redesignated B/BGT) record by going 240.738 mph.
That run made the Kehoe, McKinney and Banks Corvette the “World’s Fastest Passenger Car”—an unofficial title, but one with major hot-rodding street cred.
“At the time, turbocharging was rare at Bonneville,” says Banks. “Going 240 with Sundowner—a door-slammer—while others were struggling to get over 200, was incredible. They reacted like we’d come from Mars or something.”
Early in 1983 the team split. Banks took his big-blocks racing with Pontiac, and Kehoe, who had grown anxious over the stratospheric speeds Sundowner was running, sold his share to McKinney. McKinney continued running the Corvette with various small-blocks until 1989, when he put the car in storage and began driving for other teams. Beginning in 1985, the “fastest passenger car” title went a succession of third-generation Firebirds, but the B/BGT record remained Sundowner’s.
In 2000 Bonneville racers Jon Meyer and Rick Head convinced McKinney to let them take the car out of mothballs. At the Flats that August, Meyer drove the Corvette—now powered by a 303-cube turbo small-block—to a new D/BGT record of 227.787 mph.
Sundowner was back, big time.
Six years later, the 42 car captured another record. This time it ran 248.028 in C/BGT with a twin-turbo 355 in the engine bay and McKinney at the wheel.
Finally, at Speed Week in 2010, David McKinney went 251.838 while running a 388-inch motor. This performance reset the B/BGT record and proved that Sundowner was still the fastest stock-body Corvette ever.
“Landspeed” Louise Noeth, who covers Bonneville for major media outlets and wrote a book about Salt Flats racing, says of Duane McKinney, “This guy is a pioneer, one of the last few walking the salt who can say, ‘I was here for the first one.’
“Engage him in a friendly chat, and odds are you’ll go home wiser—and maybe faster, if you listen to his speed wisdom. He’s the epitome of a speed-record competitor, equally ready to smash your record or help you trash his own.”
But despite all the accolades he’s garnered over his four-decade racing career, McKinney notes that his greatest Salt Flats memory has nothing to do with personal achievement.
“The records didn’t mean as much as getting my brother into the ‘2-Club’,” he says. “Best thing I ever did in my life. He was always the one who strapped me in before a run. He had bone cancer and diabetes, and could hardly move his legs, so I modified the clutch pedal so he could push it.”
Driving Sundowner on October 17, 2002, Bob McKinney went 224.725 mph and was inducted into the Bonneville 200 MPH Club.
Bob lost his battle with cancer in 2009.
Building a Winner
At this writing, Sundowner is still running its B-class engine, a Jon Meyer–built small-block Chevy displacing 388 ci. Electronically fuel injected and fitted with two turbochargers, it produces 1,250 hp at 6,800 rpm.
The powerplant’s bottom end comprises a Chevrolet Performance “Bow-Tie” cylinder block loaded with a forged-steel crankshaft and connecting rods from Eagle Specialty Products. Bill Miller Engineering forged-aluminum racing pistons feature a compression ratio of 10:1 and use a common ring package, but with gaps specially set for a turbocharged engine running for long periods at wide-open throttle. The short-block is finished with an Aviaid dry-sump oiling system.
While a 10:1 compression ratio might seem high for a turbocharged racing engine, Meyer notes that running a higher CR in concert with lower boost levels actually makes for more-linear throttle response. This makes it easier to modulate the gas pedal in response to varying levels of traction, a critical task in a skinny-tired salt racer traveling at well over 200 mph. “In fact, doing that motor with 10:1 pistons worked so well, I may to go to 11 the next time,” Meyer says.
Sundowner’s camshaft comes from another Bonneville engine builder, Mike LeFevers. It’s a mechanical roller with .750-inch lift, but that’s about all anyone would say about it. The rest of the valve gear is a mix of Jesel (lifters, shaft rockers); Crane (valve springs, pushrods) and Comp (camshaft belt-drive) parts. A speed-density ECU from Accel operates the fuel and ignition systems.
The Brodix aluminum cylinder heads are right out of the box, except for a modification typical of turbocharged applications: a coolant inlet beneath the center exhaust ports. The heads are fitted with Del West titanium intake valves and Inconel exhaust valves.
The intake manifold was fabricated by Dave Dalgren, and the exhaust manifolds built by Rick Head. The turbos are mounted adjacent to the cylinder heads and have adjustable wastegates. The exhaust is finished with two down pipes, with one exiting behind each front wheel.
At Bonneville, virtually every competitive turbocharged engine uses a charge-air cooler (also known as an intercooler) placed between the turbos and the intake manifold. Cooler, denser air reduces an engine’s tendency to detonate and makes it possible to generate more power safely and consistently. As Meyer notes, “These days…the guy with the best intercooler wins.”
Sundowner’s air-to-ice-water system cools the intake charge as low as 50° (F). Behind the seats is a tank that crewmembers fill with water and crushed ice before each run. An electric pump circulates the ice water through the charge-air cooler. By the end of the run, the ice has melted and the water temperature has risen to about 60°.
Over the years, rumors have circulated of a rubber duck riding along in Sundowner’s ice-water tank as a kind of good-luck charm. We can confirm that the ducky is indeed there, though the little guy is today somewhat worse for wear, having withstood numerous freeze-thaw cycles at over 200 mph.
The engine’s cooling system is also of an alternative design. While it’s possible to improve aerodynamics by blocking airflow to the radiator, the SCTA requires a functional radiator in its stock-body classes. In a stroke of creative genius, the Sundowner team fabricated a custom fuel tank and mounted it just ahead of the radiator to block airflow. To meet the functionality requirement, coolant is routed from a reservoir in the stock fuel-tank location, up to the engine, through the radiator and back.
The transmission is a race-prepared Turbo-400 automatic with no torque converter or clutch. While the trans has a Neutral, the car is not capable of a standing start, and it must be pushed to a speed where it can be shifted into Low without stalling the engine. An electric pump provides line pressure when the engine is off and the car is being pushed.
Sundowner’s front suspension is stock, save for three modifications. To enhance straight-line stability, caster has been reset to a whopping nine degrees. The car also uses a stock 1.125-inch FE7 front stabilizer bar from a ’74-’82 model. Lastly, the front brakes have been removed.
The steering system started with a stock C2/C3 gearbox, but the power assist has been removed and the outer tie-rod ends moved to the slow-ratio holes in the steering arms.
To eliminate camber change and toe steer when the driver lifts off the gas, Sundowner’s three-link IRS has been replaced with a 12-bolt axle out of a late-’60s Chevrolet Impala. It has 2.29:1 gears and an open differential. Asked about the open diff, McKinney says, “I’ve run it all three ways—with a spool [locked], Positraction [limited slip] and open, and I can’t detect a difference in the car’s performance.”
Sundowner’s rear axle is narrowed and sits on a five-link suspension that McKinney fabricated. The lack of a rear stabilizer bar, combined with the big front bar, eliminates the C3’s chassis-related tendency towards oversteer. A brace of Wilwood rear disc brakes work in tandem with a parachute to haul down the car from speed.
The tires are Goodyear Eagle Dragway Special Frontrunners at each corner. They’re identical in width but slightly taller in back to increase rake (more on that anon). To improve aerodynamics, the wheels are fitted with the obligatory “Moon Disc” covers.
Land-speed racing is one of the few motorsports in which adding weight can actually enhance performance. The ’68-’75 Corvette convertible’s exterior generates so much lift, that, at 250 mph, the only way to keep the car from taking flight is to give it a pronounced rake and add weight—a lot of it. Sundowner carries about 800 pounds of lead ballast along with the front-mounted gas tank, two water tanks in the rear, two sets of coolant pipes, considerable turbocharger hardware and a roll cage.
There’s even lead where the front license plate went, far forward of the car’s center of gravity, to help limit front-end lift. Needless to say, extra mass ahead of the front wheels and over the rear wheels gives the car a high polar moment of inertia—just one more reason why driving this 1,250hp C3 at 250 on salt takes both skill and nerve.
McKinney’s specialties are metal fabrication, bodywork and painting, skills honed over the years as he worked in partnership with veteran salt racer Jerry Kugel. Not surprisingly, McKinney craftsmanship is all over Sundowner: Duane performed the chassis- and interior-fabrication work, while son David helped out with the body and paint. Sundowner’s striping and lettering were applied by Dennis Jones.
In 2013 the McKinneys were invited to display Sundowner at the Petersen Automotive Museum in LA during a month-long celebration of Corvette’s 60th anniversary. For that, David touched up the body and gave the Bonneville record holder a fresh coat of Le Mans Blue.
Though Duane McKinney talks about retiring Sundowner, that seems unlikely in the near term. In 2010 the car managed to hit 254 mph and was still accelerating at the end of the course. Had it been able to build more speed earlier in the run, 260 or even 265 might have been possible.
Duane plans to take the blue 42 car to Speed Week again in 2014. It’s possible that, by the time you read this, a McKinney will have strapped into the famed land-speed Corvette and set yet another Bonneville record—probably at right around sundown.