More Details Offered On New Hellcat Hemi Engine

We have additional information on new supercharged 6.2-liter Dodge “Hellcat” Hemi that will power the upcoming Challenger SRT and Charger SRT. While horsepower numbers still haven’t been released — Dodge is promising 600-plus and industry observers continue suggesting 650-plus — there are more details on the engine’s components and specs.

The Hellcat will be the Chrysler Group’s most powerful V8 engine and built with 91 percent new content when compared to the standard 392 Hemi. The foundation is an orange powdercoated cast-iron block with redesigned coolant passages. It’s fitted with a forged-steel crankshaft that Dodge says can withstand cylinder pressures up to 110 bar, or 1,595 psi. Crank vibrations are controlled with a specially tuned damper capable of 13,000 rpm. Forged aluminum pistons, powder-forged connecting rods and DLC pins make up the remainder of the rotating assembly.

The supercharger is key to the engine’s performance and puts Dodge on a more level playing field with the blown competition from the ZL1 Camaro and GT500 Mustang. The twin-screw rotors are specially coated to accept tighter tolerances and higher temperatures as well as resisting corrosion. Rated at 2,380cc per rev, the supercharger will be overdriven 2.36:1 for a max speed of 14,600 rpm. Fresh air is fed to the blower through an inlet port mounted where the driver’s-side marker light was located, and then routed into an 8-liter air box. The Hellcat relies on an integrated electronic bypass valve to regulate boost at 11.6 psi max and a huge 92mm throttle body to control power.

Fuel delivery was improved to satisfy the engine’s elevated thirst, including half-inch fuel lines and 600cc/min fuel injectors. Cooling the boosted air charge before it mixes with the fuel are two air-to-water intercoolers mounted in the supercharger housing. Dodge says the system is designed to keep intake charges cooled down to 140 degreesF.

“So effective is this feature that engine power will not be de-rated due to cooling demands, even after 20 laps of a grueling 3.1-mile road course at an ambient temperature of 100 degrees Fahrenheit (37 degrees Celsius).” claims Dodge.

Lubrication was also improved with a high-flow gerotor pump, oil-to-air heat exchanger and piston cooling jets. The heat-treated alloy cylinder heads hold sodium-cooled steel exhaust valves that can withstand 1,472F temperatures. Dodge says the valve lift will be .561 and .551 respectively for the intake and exhaust valves. And speaking of exhaust, the Challenger SRT will utilize a electronically controlled relief valve to accentuate the exhaust note booming through the dual 2.75-inch pipes. (see video below)

Finally, Dodge says its engineers ran the engine over 2 million customer-equivalent hours on the dyno as well as 24-hour endurance tests on the track. Another test included 125 consecutive drag-race starts.

Dodge promises more information is forthcoming, so stay tuned.

About the author

Mike Magda

Mike Magda is a veteran automotive writer with credits in publications such as Racecar Engineering, Hot Rod, Engine Technology International, Motor Trend, Automobile, Automotive Testing Technology and Professional Motorsport World.
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