Hemi engines come in regular and extra strength varieties, displacing 5.7-liters and 6.1-liters, respectively. The 2006 Jeep Grand Cherokee SRT-8 is powered by the regular strength Hemi, offering 415 horsepower at 6,200 rpm and 410 lb.-ft. of torque at 4,800 rpm. Company officials claim that’s enough to get this Jeep to 60 mph in less than five seconds. A five-speed automatic transmission is standard.