It’s faster than a revved up Porsche Cayenne Turbo. It laughs in the face of a BMW X5 and accelerates to 60 mph faster than a new Mustang GT. The new supercar, Jeep’s noisy Grand Cherokee SRT8, is equipped with a powerful 6.1-liter Hemi V8, making 420 horsepower and 420 pound-feet of torque. This SUV family truck is definitely not your average SUV and you’ll know that soon enough once you hear its throaty roar as it hits a quarter-mile in a matter of 13.5 seconds, which is just muscle car territory by the way.
Despite the power delivered by the Jeep Grand Cherokee SRT8, it still doesn’t match the performance of the Dodge Viper SRT10 Coupe and for this very reason Hennessey Performance created the new SRT600 package. Hennessey Performance was the same person responsible for fine-tuning the Viper, and because it always wants to create something more powerful than its previous masterpiece, it has developed the performance package that will allow the Grand Cherokee SRT8 to finally defeat the ferocious Dodge V10 Viper in a Sprint from 0 to 60 and a quarter mile.
Actually, this has already been achieved with the new Hennessey SRT600 fortified Jeep, the Viper being topped at 60 mph by half a second and crossing the quarter-mile finish line two-tenths sooner than a much lower and lighter Viper.
Ever wonder where the Jeep’s added Saturn V-like oomph comes from? Instead of a solid rocket propellant, a large Garrett turbocharger has provided the boost to a modified 6.1-liter V8. How did Hennessey Performance achieve this? They first started by removing the stock SRT8 V8 and stripping it down to the cast iron cylinder block. Later, heavy-duty bearings were added before the installation of aftermarket forged steel connecting rods, 9.5:1 forged aluminum piston, and performance piston rings.
Hennessey also modified the cylinder heads by creating full port intake and exhaust runners along with polished combustion chambers. And on Hennessey’s airflow test bench, the ported heads flow 360 cfm out of each inlet port, which is about 60 cfm more than stock.
To further increase airflow to the cylinders, a single Garrett T4 turbocharger has been added that provides seven psi of thrust. Custom-built stainless steel headers deliver exhaust to the turbo, then boost is fed through polished stainless steel 3.5-inch pipe, a large front-mount air-to-air aluminum intercooler and intake pipe. Custom packed with dual billet aluminum blowers. off the valves. Keeping turbo boost in check is a single 44mm wastegate, while the 180-degree thermostat helps the Hemi stay cool.
Hennessey has also added a high-volume fuel pump that provides a continuous flow of gasoline; likewise, oversized fuel injectors and a special fuel pressure regulator are being monitored by a custom-programmed engine computer. The result of all these processes is a 6.1-liter V8 that delivers 600 horsepower at 5,200 rpm backed by 650 pound-feet of torque at 4,000 rpm. Such powerful torque requires a lot of airflow from the engine, which led Hennessey to install a three-inch-diameter stainless steel dual exhaust system, high-flow mufflers, and four-inch-diameter polished exhaust tips. At rest, the SRT600 is like a tame lamb, but try to put the throttle to the floor and it wakes up like a monstrous beast. A word of caution: The Hennessey SRT600 Jeep SRT8 is not for the faint of heart.
Modifications made to the Jeep SRT8 were kept to a minimal level, which means that aside from the engine, basic SRT8 components such as the Jeep fuel filter, factory SRT-spec Brembo disc brakes and many more, were not modified. However, the exterior was upgraded by the addition of some SRT600 badging and optional 20×10.5-inch forged aluminum wheels wrapped in Michelin Pilot Sport 2 295/30ZR20 tires.