Dodge Charger Hellcat engine: made to be legendary

2015 Dodge Charger SRT Hellcat

In over a century of automobile production, only a handful of vehicles have become legendary. Say the name Mustang, Corvette, or Challenger, and people know exactly what you’re talking about. But while these and a few other nameplates have reached legendary status, a short list of engines can make that same claim. Say Cleveland 351 or 5.0, and every Ford enthusiast nods his head. Mention HEMI, and even non-enthusiasts can tell you who makes it. Throw out the letters LS, and Corvette and Camaro people come running. But with the onslaught of hybrids, electric vehicles, and fuel-efficient four bangers ruling the roadways today, big engines with big expectations have become the exception rather than the norm. And while we are all for improving fuel efficiency and reducing our dependency on foreign oil, we can’t help but feel sorry for those who come after us who may never know the thrill of loud, powerful V8s thundering down the highway.

Lucky for all of us that Dodge understands the visceral thrill of raw power under the hood of an American muscle car. And we also are grateful that there are still more than a few motorheads at Dodge who will stand up and defend the right to build vehicles that deliver on the promise of raw performance.

President and CEO of Dodge and SRT, Tim Kuniskis, understands the need for big horsepower.

President and CEO of Dodge and SRT, Tim Kuniskis, understands the need for big horsepower.

Whether or not it makes sense to produce a 707-horsepower engine is not the question. Tim Kuniskis, president and CEO of Dodge and its performance division SRT, gets this. At a recent introduction and drive of the new lineup of 2015 Chargers, including the Hellcat model, Kuniskis said that sometimes you just have to “ignore the data and disregard the focus groups.” To him, and the SRT team, it’s more than sales numbers. It’s about building a car [Charger] that “defines the whole brand.” And this engine is what will help define the new Charger.

While I’ll cover the Charger lineup and the driving experience in another article for, I just want to concentrate on the Hellcat engine here. Why? Because it’s been too long since a manufacturer created a monster V8 and put it in a family sedan.

HC CB engine 2The Hellcat engine, recently introduced in the Challenger and now for sale in the top trim level of the Charger four-door full-size sedan, is a 6.2-liter supercharged OHV HEMI V-8. Dodge notes that the new engine features over 90 percent new components versus the 392 HEMI V-8 found in lower-trim Charger models. Because this massive engine makes 707 horsepower and 650 lb-ft of torque, SRT knew it had to use strong materials for durability. This HEMI features a cast-iron block and premium-grade heat-treated aluminum alloy for the cylinder heads. Other performance-oriented parts include high-strength forged-alloy pistons, powder-forged connecting rods with high-load-capacity bushings, and carbon-coated piston pins with diamond-like strength. In addition, a forged-steel crankshaft features induction-hardened bearing surfaces. Dodge says the crank has the ability to withstand firing pressures of almost 1,600 psi (110 bar), or the equivalent of five family sedans standing on each piston, every two revolutions. And the tuned crank damper has been tested to 13,000 rpm.

Equal to durability is the importance of cooling. With a engine that makes this much power, all parts and pieces need to be focuses on controlling heat buildup. The heads are heat-treated, and the sodium-cooled exhaust valves with hollow stems and special steel-alloy heads can withstand temperatures up to 1,472 degrees Fahrenheit.

Hellcat in vehicle cBThe massive IHI 2,380cc/rev supercharger features components especially designed for performance and heat resistance. It includes integral charge coolers, an electronic bypass valve for boost pressure regulation (maximum 80 kPa or 11.6 psi), and twin-screw rotors that are coated with wear-resistant particles, non-stick solid lubricants, and a proprietary polyimide formula, along with other resins. This coating helps form tighter tolerances between the rotors, which in turn reduces internal air leaks to help deliver higher efficiency and better compression. Two other benefits of the coating are the ability to withstand high temps generated by compression, and a resistance to corrosion.

The supercharger grabs air through Dodge’s Air Catcher (located behind the grille) inlet port connected to a patented twin-inlet, eight-liter airbox. The supercharger has its own cooling system, which includes a low-temp circuit with two air/coolant heat exchangers integrated into the housing. Under extreme ambient conditions, the system keeps air temps below 140 degrees F while still allowing airflow of up to 30,000 liters per minute. The engineers did such a great job with cooling this system that even after 20 minutes of hard driving on a track with air temp at 100 degrees F, the engine will lose no performance.

The supercharger is sealed for life with premium synthetic oil, and turns a maximum of 14,600 rpm with a drive ratio of 2.36:1. It also features a one-way clutch de-coupler, which delivers the high-performance sound quality we all can’t resist.

engine cutaway cbFor oil cooling, the large-nose crank works a high-flow gerotor oil pump to move oil through eight high-flow piston cooling jets. There’s a high-capacity oil/air heat exchanger located in the front of the car that helps control oil temp when pushing the Charger Hellcat around the track. To make sure the Hellcat runs exactly how the engineers designed it, SRT — in conjunction with Pennzoil — developed a 0W-40 synthetic oil especially for SRT vehicles. Finally, a unique fuel pump was designed to handle variable pressures, with half-inch fuel lines and eight injectors, with each delivering a flow rate of 600cc per minute.

Because this engine went above and beyond any production engine from Dodge to date, obviously durability tests were paramount. But that meant upgrading the process with new laboratories, featuring dynamometers with the capability to measure the high-performance engine. Dodge says it conducted almost two million customer-equivalent hours of dyno testing on the big engine for long-term performance and quality. Every engine spent almost an hour on the dyno for a shakedown after 100 consecutive drag starts at the track. Only after it passed did it get shipped to Brampton, Ontario, Canada, where the Charger is assembled.

Because the engine is so powerful, the Charger Hellcat also had to be fitted with a new 230mm rear axle to support the torque output, along with gigantic brake rotors to stop the vehicle. In addition, the unique hood and front fascia provide more air intakes and air extractors to keep the cooling system on track.

HC badging CBBottom line: The Charger Hellcat delivers an 11.0-second NHRA-certified elapsed quarter-mile time, and features a top speed of 204 mph. It also will drain the gas tank in 13 minutes if you run at full throttle the whole time. Now that’s impressive. (Whining tree huggers please leave.)

There are many other features that go along with this engine, such as two keys for different engine outputs, eight-speed transmission, customizable performance settings, and more, but this HEMI is the new king of all HEMIs, and that’s saying a lot. While it may take some time before this 6.2-liter reaches legendary status, there’s no doubt it will have a special place in automotive history.

  Photography courtesy of Dodge;  BJ Killeen/Team Killeen