Holy Hellcat HEMI^®, This Engine’s 10 Years Old

It’s hard to believe it was 10 years ago when Dodge unleashed the 707-horsepower, 6.2L supercharged HEMI^®, known as the ‘SRT^® Hellcat.’ This apex predator forever changed the industry while devouring its competition. It outlived its grandfather, the 426 HEMI engine, which Chrysler made from 1964 to 1971. Like its grandfather, the SRT Hellcat forever changed the automotive landscape and car culture by providing insane amounts of horsepower to the masses. The SRT Hellcat engine raised the bar among its crosstown Motor City rivals and automakers across the pond. This engine put light-years between Dodge and anything the Ford, GM and even those upscale and high-end European brands that produced self-proclaimed supercars could assemble. The SRT Hellcat kicked the door down in the 21st-century horsepower race.

While the vision of the 6.2L SRT Hellcat may have originated from the main man at Dodge, Tim Kuniskis, the project had to be blessed by the big boss at FCA during that time, Sergio Marchionne. Once approved, the team of ravenous SRT gearheads got to work and put their noses to the grindstone on creating a weapon of mass destruction. It was an all-hands-on-deck approach that brought together the smartest minds within the halls and dyno cells of the vast World Headquarters up in Auburn Hills, Michigan. They knew it would be a challenge to produce such a monster that would still need to meet strict EPA requirements and pass intense durability testing. The engine was officially announced during a Dodge Press Conference at a former gas station/auto repair shop now turned restaurant, Vinsetta Garage, located in the epicenter of Woodward Avenue’s celebrated cruising scene. So here’s a little on how one of the iconic HEMI engines, now infused with a supercharger and other goodies, once again became a formidable force and struck fear into the competition.

One engineer who was in the thick of the SRT Hellcat’s development was Jim Wilder. He led the charge in making sure the supercharged SRT Hellcat engine exceeded everyone’s goals and expectations regarding performance and durability. Bolting superchargers on production engines was unknown territory for FCA, but the SRT group knew the naturally aspirated 392/6.4L HEMI, the highest factory-rated horsepower for a Chrysler V8 at that time, was being outmuscled by Chevy and Ford. “I was Development and Synthesis manager for the Charger & 300, and the plan was to roll the engine out in the Challenger and Charger.  Adam Forte had the lead on Challenger, and on our timeline, was ahead of the Charger. He worked with our outside vendor, Arrow Racing, to get a 6.4L HEMI upfitted with an aftermarket blower for some initial testing,” recalled Jim. “I think it was making a bit over 600 horsepower. We ran the package on a road course for some initial testing, specifically on cooling, as it doesn’t matter how much power you make if you can’t cool both engine coolant and intercooler. SRT has road course requirements that demand you make max power in hot weather on a track. This isn’t for just a flying lap, but lap after lap. Initially, I didn’t make friends in the studio with requests and demands for more airflow through the grill, but in the end, we became brothers in arms in the mission to create a legend that isn’t just a numbers car, but a legit performance car. During this testing, it was also clear that the brakes were in need of a major upgrade to mitigate fade. This was the middle of 2012. Somewhere along the way, Adam (Forte) got a new job, and since the Challenger was the lead vehicle for SRT Hellcat integration and backfilled his position. I loved and still love the Charger, but moving to the Challenger was a dream come true.”

There were many challenges Jim and the team faced during the development of the SRT Hellcat engine. “Making all the power in the world, but not passing emissions means you don’t have a car for sale. The same is true for engine durability, and the team came up with a brutal dyno cycle that combines race track and drag strip abuse that runs over and over again,” noted Jim. “Another struggle we had was getting the noise right. A muscle car needs to sound good and tough. That’s not a line on a chart or curve, it’s your ears telling you that the sound matches the car. The supercharger whine and exhaust note are a big part of the package. The exhaust shouldn’t be pumped in; it is a natural part of the combustion process and is just massaged slightly to highlight the wonderfulness of the V8’s firing order. Same for the blower, it should whine and make noise, but at the right time and throttle position, which getting right took a host of NVH (Noise Vibration Harshness) and calibration engineers. In my opinion, we nailed it. You can close your eyes, and when you hear the distinct supercharger whine and menacing exhaust rumble, you know it’s 6.2L SRT Hellcat!”

Due to the importance of the SRT Hellcat program, it was a very ‘hush-hush’ project, and only a select few within FCA knew about the program. “Although this was a super-secretive program, I was in the trust circle with the powertrain guys, so I got inside information. When the possibility of over 700 horsepower was first realized, the team kept working. The ‘707’ number had a nice ring to it and was our horsepower target, and it easily met the goal. I will never forget when we did a pre-media event with an automotive journalist with the car before the official reveal, and during the event, Tim Kuniskis disclosed the horsepower number to the journalist, he went silent with his jaw hit the ground,” smiled Jim.

In the early stages of the supercharged 6.2L HEMI, the ‘Hellcat’ name was chosen and followed the SRT group’s method of giving code names to their engines based on military aircraft. “The 6.4L HEMI was given the code ‘Apache’ in honor of the US Army’s attack helicopter. That same theme followed and we called the new engine ‘Hellcat’ in honor of an iconic World War II Naval Fighter. It’s such a cool name and fits very well,” commented Jim.

After the debut of the SRT Hellcat in the 2015 Challenger and Charger SRT models, this powerhouse would take up residence in the 2018 Jeep_® SRT Trackhawk, 2021 Dodge Durango SRT and 2021 Ram 1500 TRX. Since it lit the world on fire, the SRT Hellcat has seen a bump in horsepower in the Redeye models. It also served as the foundation for the SRT Demon and SRT Demon 170, which again, continued the original mission of a scorched earth policy and destroying everything in its path. You can also buy a SRT Hellcat Crate HEMI to install into any vintage vehicle.

So happy birthday, you ferocious feline. The past ten years have flown by, and we’re looking for all that horsepower goodness driven by a howling supercharger and intimidating bark from the exhaust to go for another decade!