FCA has unveiled its most powerful and fastest SUV in the 707hp, 6.2-liter V8 powered Grand Cherokee Trackhawk.
The supercharged engine is designed and manufactured using ‘only the strongest and most durable materials’ according to Jeep. Its cast iron block features water jackets between the cylinders for optimal cooling. A forged-steel crankshaft with induction-hardened bearing surfaces is so strong it can withstand firing pressures of nearly 1,600psi (110-bar) – the equivalent of five family sedans standing on each piston, every two revolutions. The unique, specially tuned crankshaft damper has been burst tested to 13,000rpm.
High-strength, forged-alloy pistons – developed using advanced telemetry measurement – are coupled to powder-forged connecting rods with high-load-capacity bushings and diamond-like, carbon-coated piston pins. Premium grade, heat-treated aluminum-alloy cylinder heads are used for superior thermal conductivity. Sodium-cooled exhaust valves feature hollow-stem construction and special steel-alloy heads that stand up to temperatures as high as 1,652°F (900°C).
The 2,380cc per revolution supercharger includes integral charge-air coolers and an integrated electronic bypass valve to regulate boost pressure to a maximum of 11.6psi (80-kPa). The twin-screw rotors are specially coated with a proprietary formula of polyimide and other resins, nanometer-sized, wear-resistant particles and solid lubricants, such as PTFE (Teflon)
The coating enables tighter clearance between the rotors. This reduces internal air leakage, delivering improved compressor performance and higher efficiencies. The coating can withstand the temperatures generated by compression, and provides superior corrosion resistance.
The supercharger is sealed for life with premium synthetic oil, uses a drive ratio of 2.36:1 and has a maximum speed of 14,600rpm. The supercharger drive system’s one-way clutch de-coupler improves refinement, while allowing for precisely the kind of powerful sound certain to captivate Jeep Grand Cherokee Trackhawk drivers.
Air sources for the supercharger include a cold-air scoop in the lower front fascia, which replaces the driver’s-side fog lamp and helps to feed the 92mm throttle body.
The large-nosed crankshaft drives a high-flow gerotor oil pump, which feeds a lubrication circuit that includes eight high-flow piston-cooling jets. A high-capacity oil/air heat exchanger, mounted in the front of the Trackhawk, mitigates oil temperatures when driving conditions are harshest, such as on the track.
A new low-temperature cooling system, consisting of a pump, reservoir, heat exchanger and lines, help keep the charge air cool during performance driving. This system is designed to keep intake air temperatures below 140 degrees Fahrenheit (60 degrees Celsius), under extreme ambient conditions, while enabling air flow of up to 30,000 liters per minute. Whilst a new fuel delivery system, featuring two high-flow, multi-mode pumps, matches the high-performance demands of the engine round out the model specific revisions to the 6.2-liter unit.