Hennessey Goliath 700: The 700-HP GMC Sierra AT4 That GMC Never Built

 For years, the high-performance off-road truck segment has been dominated by monsters like the Ford F-150 Raptor R and the Ram 1500 TRX. Both trucks embraced the philosophy that more horsepower, more suspension travel, and more attitude are always better. GMC, despite sharing much of its engineering DNA with Chevrolet, never built a direct rival. While the Sierra AT4 and AT4X offered impressive off-road capability, neither came close to matching the outrageous power figures or desert-running credentials of their Ford and Ram counterparts. That left a gap in GMC’s lineup, and it was a gap that Texas-based tuning specialist Hennessey Performance was more than happy to fill. Enter the Hennessey Goliath 700, a heavily modified GMC Sierra AT4 that transforms the premium pickup into a genuine super truck. Rather than starting with the diesel-powered version, Hennessey selected the Sierra’s optional 6.2-liter naturally aspirated V8 as the foundation. From there, the company applied decades of performance expertise to create a machine capable of embarrassing sports cars at traffic lights while still tackling rough terrain with confidence. The result is a truck that combines GMC luxury with extreme performance, creating something that many enthusiasts believe GMC should have built from the factory. For buyers wanting Raptor R levels of excitement but wrapped in a more premium package, the Goliath 700 provides a compelling alternative.

A Supercharged V8 Producing 700 Horsepower

The heart of the Goliath 700 is its extensively upgraded 6.2-liter V8 engine. While the standard Sierra AT4 already offers respectable performance, Hennessey felt it needed considerably more muscle. To achieve that goal, the company fitted a high-performance supercharger system designed to dramatically increase airflow and power output. Supporting modifications include a high-capacity air-to-water intercooler that keeps intake temperatures under control, ensuring consistent performance even under demanding conditions. Hennessey also recalibrated the engine management software and installed a stainless-steel cat-back exhaust system featuring aggressive black-finished exhaust tips. The final result is an astonishing 700 horsepower delivered at 5,500 rpm alongside 611 lb-ft (828 Nm) of torque available at 4,200 rpm. Those figures place the Goliath 700 firmly within the same territory occupied by some of the most powerful factory-built trucks on the market. The additional power transforms the driving experience, giving the Sierra an entirely different character from the stock model. Acceleration becomes brutally quick, overtaking requires little effort, and the truck delivers the kind of relentless thrust normally associated with high-performance muscle cars. Despite the huge power increase, Hennessey engineered the package to remain usable as a daily driver, maintaining reliability and drivability while dramatically elevating performance beyond anything GMC currently offers.

Supercar Acceleration In A Full-Size Pickup

One of the most shocking aspects of the Hennessey Goliath 700 is how quickly it accelerates. Full-size pickups traditionally prioritize towing capacity, payload ratings, and comfort rather than outright speed. However, the Goliath 700 completely rewrites those expectations. Thanks to its massive power output and carefully optimized drivetrain calibration, the truck can sprint from 0 to 60 mph in just 4.2 seconds. To put that into perspective, that acceleration figure rivals many modern sports cars and luxury performance sedans. A few years ago, achieving such numbers in a vehicle weighing well over two tons would have seemed almost impossible. Yet the Goliath accomplishes it while retaining four-wheel-drive capability, impressive cargo capacity, and genuine off-road credentials. The combination of instant torque and supercharged power delivery means the truck feels explosive from virtually any speed. Whether launching from a stoplight, merging onto a highway, or overtaking slower traffic on a two-lane road, the Goliath responds with remarkable urgency. This extraordinary performance is precisely what has made high-powered trucks so popular in North America. Buyers increasingly want vehicles capable of performing multiple roles, and the Goliath delivers. It can tow trailers, transport equipment, handle difficult terrain, and still produce acceleration figures that would embarrass many dedicated performance cars. That versatility is a major reason why trucks like the Goliath continue to attract attention from enthusiasts seeking the ultimate all-purpose vehicle.

Off-Road Hardware To Match The Extra Power

Simply adding horsepower would not have been enough for Hennessey. A truck producing 700 horsepower also needs suspension and chassis upgrades capable of handling both the increased performance and serious off-road use. To achieve this, Hennessey equipped the Goliath 700 with upgraded front suspension components and new upper control arms designed to improve durability and handling characteristics. The truck also retains Multimatic DSSV dampers, which are widely regarded as some of the best off-road shock absorbers available today. These sophisticated dampers provide excellent control both on pavement and in demanding off-road conditions. Hennessey further enhances capability with a set of rugged 20-inch wheels wrapped in massive 35-inch off-road tires. The larger tire package improves ground clearance, traction, and obstacle-climbing ability while also giving the truck a much more aggressive stance. Together, these upgrades ensure the Goliath is not merely a street-focused performance truck but a genuinely capable off-roader. Whether navigating rocky trails, crossing desert terrain, or tackling muddy backroads, the upgraded chassis is designed to keep pace with the engine’s substantial power output. The result is a truck that remains balanced and confidence-inspiring even when driven hard. Rather than compromising off-road ability in pursuit of speed, Hennessey has created a package that enhances both aspects simultaneously, making the Goliath 700 one of the most versatile high-performance pickups currently available.

Aggressive Styling Inspired By Baja Racers

Visually, the Goliath 700 leaves no doubt that it is something special. While the standard Sierra AT4 already has a rugged appearance, Hennessey dramatically amplifies its presence with a series of functional and cosmetic upgrades. At the front, a heavy-duty steel bumper gives the truck a more purposeful look while improving durability in challenging environments. Matching steel protection continues at the rear, creating a cohesive off-road-focused design. One of the most eye-catching additions is a massive 40-inch LED light bar mounted prominently for enhanced nighttime visibility. Additional three-inch LED pod lights further improve illumination during off-road adventures. Hennessey also incorporates custom badging throughout the vehicle, ensuring the truck’s exclusivity is immediately recognizable. Carbon-fiber accents on the tailgate add a touch of modern performance styling, while electronic power running boards improve accessibility without compromising ground clearance. Beneath the front end sits a Hennessey-branded skid plate designed to protect critical components during off-road excursions. Every modification serves a purpose, blending visual aggression with genuine functionality. The overall effect is a truck that looks ready for a Baja race while maintaining the premium appearance expected from a GMC. It is significantly more intimidating than the standard Sierra and perfectly communicates the performance hidden beneath its sculpted bodywork.

The Closest Thing To A GMC Raptor R

Although GMC has never officially built a direct competitor to the Ford F-150 Raptor R or the Ram 1500 TRX, the Hennessey Goliath 700 effectively fills that role. It combines luxury, capability, and extreme performance into a single package that appeals to enthusiasts seeking something unique. The interior receives subtle upgrades, including embroidered headrests, exclusive floor mats, and serialized plaques that remind owners they are driving something far more special than a standard pickup. Hennessey also backs its work with a three-year or 36,000-mile limited warranty, providing additional confidence for customers investing in such an extensive conversion. Beyond the numbers and hardware, the Goliath 700 represents a different philosophy in truck performance. Rather than waiting for manufacturers to build increasingly extreme factory models, companies like Hennessey demonstrate what is possible through aftermarket engineering. The result is a vehicle that offers supercar acceleration, genuine off-road capability, premium comfort, and distinctive styling all within a familiar GMC package. For drivers who admire the Raptor R and TRX but prefer the refinement and appearance of the Sierra, the Goliath 700 may be the ultimate solution. It is bold, excessive, and unapologetically powerful—exactly the kind of truck Hennessey has built its reputation on creating.