The 2015 Dodge Challenger SRT Hellcat is the most powerful muscle car ever thanks to its 6.2-liter supercharged HEMI® Hellcat V-8 capable of churning out 707 horses.
Tim Kuniskis, President and CEO – Dodge and SRT Brands says, “The new 2015 Dodge Challenger is the perfect street / strip muscle car. As the fastest muscle car ever, the Challenger Hellcat can run 10-second ETs at the track, and then get 22 miles per gallon on the drive home. With a starting price of $59,995, there’s nothing else that even comes close.”
If not offset properly, the Charger would experience extreme loads and result in catastrophic failures so there was extreme attention to detail when manufacturing the engine.
The HEMI Hellcat takes advantage of premium-grade, heat-treated aluminum-alloy cylinder heads that are optimized for thermal conductivity. The cylinder heads are topped by a twin-screw 2,380-cc/rev supercharger that features integral charge coolers and an integrated electronic bypass to regulate boost pressure to a maximum of 80 kPa (11.6 psi).
While most Hemis use standard 319-grade aluminum for the cylinder head, the new head utilizes 356-grade aluminum alloy with a special heat treatment.
Chris Cowland, Chrysler’s director-Advanced and SRT Powertrain says, “The thermal conductivity of 356 is significantly better. It enables us to take heat from the combustion chamber. It stops engine knocking, and we get the performance we need.”
Exhaust valve stems are sodium-filled and intake valves are hollow and lighter, which allows heat to be drawn away from the valve head.
A low-temperature cooling circuit equipped with two air/coolant heat exchangers integrated into the supercharger housing helps keep air temperatures sub 140 degrees Fahrenheit, while also allowing air flow of up to 30,000 liters per minute.
Cowland offered a word of advice to Hellcat engine enthusiasts striving to build their own without using the cooling system. “If you want to generate 707 hp and you don’t take the coolant system with it, it won’t work.”