The supercharged 6.2-liter HEMI V-8 powering the Challenger SRT Hellcat shares just 9 percent of its componentry with Dodge’s 6.4-liter V-8. Its cast-iron block features unique water jackets to deliver optimal cooling and inside there’s a forged-steel crankshaft with induction-hardened bearing surfaces, allowing it to withstand firing pressures of 1,595 psi.
High-strength, forged-alloy pistons are coupled to powder-forged connecting rods with high load-capacity bushings and diamond-like carbon-coated piston pins. The cylinder heads are also heat-treated for improved thermal conductivity and sodium-cooled exhaust valves feature hollow-stem construction and special steel-alloy heads that can withstand temperatures as high as 1,472 F (800 C).
The new twin-screw supercharger, sealed for life with premium synthetic oil, boasts a drive ratio of 2.36:1 and a maximum speed of 14,600 rpm. The 2.4-liter blower features integral charge coolers and an integrated electronic bypass valve to regulate boost pressure to a maximum of 11.6 psi. After leaving the engine, the now superheated gases are directed rearward via a 2.75-inch, straight-through, twin-exhaust system with an electronically controlled valve to control the sound.
The fuel system keeps pace with an in-tank pump that accommodates variable pressures, half-inch fuel lines and eight high-flow injectors that can drain the car’s 18.5-gallon fuel tank in just 13 minutes when the engine is running at full power.
Drive in the 2015 Challenger SRT Hellcat goes to the rear wheels only, via a six-speed manual borrowed from the Viper supercar or a new eight-speed automatic. Modifications to both units, mostly to allow them to handle the high torque output, make them unique to the Challenger SRT Hellcat.
New axles also deliver greater efficiency and the capacity to withstand high torque. The 2015 Challenger SRT Hellcat's 230-mm rear axle also provides for efficiency improvement, compared with the one it replaces. Design features that contribute to the axle's efficiency gains include lightweight construction, new cooling fins, low viscosity fluid and specially designed bearings. The new driveshaft and half-shafts also benefit from premium lubricants designed for high-speed operation.
An asymmetric limited-slip differential allows for unique bias-ratio tuning for on- and off-throttle behavior. This serves to enhance grip, stability and steering response, enabling smooth power delivery for hard acceleration on corner exits. When trail-braking, the differential further tightens to stabilize the car and prevent oversteer.
Finally, the 2015 Challenger SRT Hellcat rides on 20-inch forged aluminum wheels that measure 9.5 inches across and are shod with 245/45 Goodyear tires (Pirelli P Zeroes are available). Inside these are the largest brakes ever offered in a Chrysler passenger vehicle, with the rotors up front, from Brembo, measuring 15.4 inches across. They are clamped by six-piston calipers.
Stay tuned for more details on the 2015 Dodge Challenger SRT Hellcat to be released as we approach the car's showroom debut towards the end of the year.