Truckin
GMC trades Bonneville salt for NHRA asphalt
BY BRIAN McCORMICK
GMC Truck Motorsports has always taken their business seriously. So seriously, that they will stop at nothing to change the record books and impress the public. In the December 1990 issue of Truckin’ magazine, we brought you coverage of GMC’s attempt at setting a new world’s land speed record on the salt of Bonneville with veteran race driver, Don Stringfellow at the helm.
Based upon a modified Syclone S-15 format, the pickup underwent a multitude of changes that ultimately put the truck over the 200 m.p.h. mark with an average record setting speed of 204 and change. At certain points, the truck even obtained speeds exceeding 210 m.p.h. but those figures were overridden by calculated average procedures.
After the high of their accomplishment had settled in, the GMC staff, along with Don Stringfellow, conjured-up the idea of redesigning the truck for NHRA competition. Why not, they proved their theories and techniques in top-end performance, now it was time to terrorize the quarter-mile.
If you have attended any of the NHRA Championship Drag Racing events over the past ’92 season, then I’m sure that you have seen Don Stringfellow in the recreated Syclone LSR, now titled “Super Coupe.” Don frequently pilots the GMC as an exhibition racer to show spectators the performance potential of GMC Truck Motorsports, the official truck of NHRA for 1992. Until just recently, the Super Coupe has been clocking an assortment of 10 second passes but at the Winternationals in Pomona, California, Stringfellow pushed the truck to a 9.85 e.t., much to the liking of 60,000 onlookers.
Okay, nine’s and ten’s are pretty quick, especially for a pickup, but let’s consider where the power is coming from. It normally
takes a punched-out V-8 to achieve these sort of times, but to see this kind of performance come from a V-6 powerplant is truly outstanding. KATECH Inc. is responsible for the engine production which is structured around a 90 degree V-6 block that features high-tech performance from a modest block with a 4.125 inch bore and 3.75 inch stroke. Final analysis reveals a 5.0 liter combustion total that delivers a 569 net horsepower rating at 7,200 rpm and 451 lbs/ft. of torque at 6,000 rpm.
But, cubic inches and horsepower are only the final result of many other harmonic factors that align this engine performance. Other specifications include a Delco Electronics CD type ignition system, programmed to the motor’s design, a Delco Generation (Gen) III fuel management system, and Bow-Tie heads with splayed valves. Add a calculated 14:1 compression ratio and it is easy to understand what makes this V-6 come to life.
Aft of the high-tech mill is a race prepared Hydramatic 3L80 transmission and nine-inch rear end for optimum performance and power transfer gains. Strange axles and 5.14:1 gears coupled with disc brakes culminate the rear end armament while Firestone Firehawk race tires make traction a breeze. Of course, none of these performance options were readily available. Both KATECH and VRD (GMC Vehicle Research and Development) spent countless hours of research to come up with the final ratio. A.s you can see, it has paid off!
Steering clear of the heart of the truck for a moment, we have to acknowledge the exterior design concept. The Super Coupe has been carefully wind tunnel tested for optimum air cutting performance and when equipped with a set of Syclone style ground effects and front bumper/air dam, the truck really slices through the atmosphere. Then, the GM Design Staff in Warren, Michigan, layed-out a few color schemes which would give the truck a visually appealing concept. The combination of pastel blue, purple and florescent green really make the Super Coupe a head turner while screaming down the quarter-mile.
Besides all that we have mentioned, there is a lot more to this truck than most enthusiasts immediately notice. For instance, the suspension is made up of precision components adjusted to align every aspect of the truck so that top performance can be gained. Front suspension consists of disc brakes and a strut front end while the rear incorporates a four-link design, all attached to a chrome moly tube chassis. Even the interior flaunts only the basics such as custom fabricated tinwork and a jungle gym of connecting roll bars.
I guess this is what you would call making the most of factory generated motorsport’s technology. It is amazing to see a truck go from one extreme to another, and excel at both! If you ever get the chance to witness Stringfellow piloting the GMC Truck Motorsports Super Coupe down the quarter-mile, make sure to check out the lights at the end of the track. The numbers will definitely impress you.
