1997 Competition Associates SuperSport Yukon: Not-So-Gentle Giant

From the November 1997 issue of Car and Driver.

Barry Brown is the kind of person who likes to do things himself. For example, when he discovered during the filming of his movie Cloud Dancer that conventional movie cameras could not handle the g-loads generated by the Pitts Special aerobatic aircraft they were using, he designed a camera that could.

In Brown’s rambling Pacific Palisades house is a harpsichord he made himself, along with several homemade hi-fi audio components. Outside in the four-car garage are two “prehistoric” racing cars­—a Tasman Cooper-Climax and a Shelby King Cobra—on which Brown has done extensive restoration work.

So it was inevitable that after he bought a GMC Yukon for use as a general runabout and tow vehicle, the car’s various shortcomings would cause him to con­template a few upgrades. One thing led to another, and the startling transformation led Brown to offer limited numbers of what he is calling the SuperSport Yukon. (Or SuperSport Tahoe, or SuperSport Sub­urban, if you prefer.) That SuperSport prefix is borrowed from the hot Chevys of yore.

Right off, Brown thought the Yukon needed more power. A K&N air filter working with Doug Thorley headers and a Borla cat-back exhaust system helped open up the truck’s breathing, and a Hypertech plug-in module (compatible with OBD II) revised the spark-advance curve, changed transmission shift points, and took care of the larger-rear-tire size for speedometer accuracy.

A Hypertech thermostat opens at 160 degrees instead of the customary 180 for cooler running, and undersized pulleys from the same company reduce engine drag and cut power-steering assist by 40 percent for better feel. A Jacobs Electronics UltraCoil and low-resistance plug leads were fitted to beef up the ignition system, and that was the extent of the engine work until Brown decided to try a supercharger as well.

The car we tested wore a Paxton blower making 5 psi of boost, which, in conjunction with Brown’s other modifications, has helped turn the Yukon from about a 10-second 0-to-60-mph sprinter into a sub­-seven-second performer—no small achievement for a 5100-pound sport-ute. Its quarter-mile time improves from 17.4 seconds at 80 mph to 15.5 seconds at 89 mph, and our 30-to-50-mph and 50-to-70-mph passing tests each shorten by about a second. Test results suggest an output of 400 horsepower and 400 pound-feet.

On the road, that translates to a dis­tinctly muscular feel, with strong acceler­ation available even at higher speeds. But straight-line grunt isn’t the SS Yukon’s most profound characteristic. It’s the way this big truck cuts through a mountain road that really impresses. It turns in cleanly with a minimum of body roll, and it holds the line with more tenacity than you’d ever expect from a vehicle of this type. That’s because the undercarriage has been sig­nificantly enhanced. In front, Bell Tech spindles drop the vehicle two inches and increase its track by 0.5 inch. A beefier 1.25-inch anti-roll bar was fitted, along with adjustable Koni shocks, Energy Sus­pension polyurethane bushings and pivots, one-inch-shorter Bell Tech springs, and A­-arms reinforced and trimmed by Precision Alignment to provide clearance for larger tires at full lock.

At the rear, Chisholm Enterprises provided custom leaf springs that lower the ride height by four inches. Custom trailing links with Heim joints from Chassis Engi­neering locate the rear axle, and a one-­inch-diameter anti-roll bar from Bell Tech is added to tame the vehicle’s penchant for understeer. Like the front end, all bushings and pivots are polyurethane, and the shocks are Konis. Adorning the axles are 8.5-by-17-inch Antera 141 wheels, with Yokohama AVS S/T tires: 265/60HR-17s up front and 275/60HR-17s at the rear.

To slow all the action down, Brown went to Baer Racing for 13.5-inch vented rotors straddled by four-piston Alcon calipers using carbon-fiber pads for the front wheel and 11-inch rotors for the rear wheels. Powered by Castrol Racing brake fluid via stainless-steel hoses, these anchors are among the most expensive items in the makeover ($6000), but they feel firm and powerful in use, and they reduced the distance taken to stop from 70 mph to just 180 feet. (A Chevy Tahoe LS we tested went 45 feet farther.)

To put the last flourish on a thoroughly revitalized chassis, Brown had NASCAR supplier Sweet Manufacturing build a blueprinted 12.0:1 steering box, and this mechanism puts the cherry on the top of the reworked SS Yukon. There’s precise on-center feel, immediate response to pres­sure at the rim, and linear increase as you wind more lock into the steering.

Coming back from our high-desert testing facility, we chose to cut through the mountains instead of droning down Highway 14 into Los Angeles, and this decision may have provided better test data (albeit subjectively) than all the numbers our instruments recorded.

To our amazement, the Yukon could be hustled through the hills like a big Mer­cedes or a Bimmer. Because the steering is accurate, the body motions tautly damped, and the tires well up to the task of keeping the big vehicle on the pave­ment, we could maintain a pace that would scare most Yukon drivers witless. Brown still talks about it every time we meet. And the extra engine power and massive brakes are always there when you need them. Of course, the creaks and rattles of the Yukon’s less-than-perfectly solid structure underline the fact that you’re not in a big German limo, but the SuperSport’s road­-going dynamics bear a greater resem­blance to those supersedans than you’d think possible.

Which is exactly what Barry Brown wanted. If you want the same thing, you can either go to the same people Brown consulted or have him do the work you want. Brown has divided the SuperSport conversion into packages. The normally aspirated upgrade costs $3700. The super­charger package runs $9725 and includes most of the first package. The suspension kit, at $13,615, isn’t cheap, but it contains several specially engineered components and really transforms the Yukon’s dynamic road feel. The cosmetic package, which includes a billet grille, replacement of the stock vehicle’s exterior trim, rose­wood interior trim, a high-zoot CD player and sound system, extra noise insulation, and the rear wing, runs $3320.

The whole package, as we tested it, would run you $27,000 installed. It sounds like a lot, but you end up with a strong sport-ute that goes and handles like a big sports sedan. All for a total cost some­where around $55,000, if you shop smart for your donor Yukon, Tahoe, or Sub­urban. It sounds okay to us.