Six months after its rollout to an eager automotive press, Dodge’s SRT Hellcat Challenger is the gift that keeps on giving. In Internet years, which are kind of like dog years, news about the Hellcat is ancient history, yet every performance vehicle that has been revealed to the world since Hellcat has, to put it bluntly, had its balls served up on a platter by the blue-collar knuckle-dragger from Auburn Hills. Ford and Chevy guys are in outright denial, and the results of the dyno test you’ll read about here nearly caused a water cooler fistfight with one of our Chevy magazine staffers. To wit, the prodigious output of the Hellcat’s 6.2L, supercharged, intercooled Hemi is so great that it has completely rebooted our expectations regarding engine efficiency. Exhibit A: My wife and I were watching TV this week when we saw the first ad for Lexus’ new $63,000, 467hp, 5.0L RC-F coupe. My wife turns to me and says in a mocking voice, “Oh, how precious! It’s got a cute little engine.”
With 707 hp on tap, the Hellcat Hemi puts out so much power that it’s almost comical. With a bright color palette, wild styling, flamboyant scoops, and flares everywhere, the SRT Hellcat is quite nearly a caricature of itself. Like conspiracy theorists who like to deny men landing on the moon, the Hellcat’s nonbelievers nitpick about road manners, build quality, curb weight, and obtuse dyno rating schemes, quoting the wine-sipping Porcheophiles from Motor Trend for moral support—anything that gives them a shred of credibility. We wanted to put all that trash talk to rest once and for all.
What we needed for the Hellcat was an impartial test venue that would take all unnecessary variables out of the equation. Driver talent, weather, track conditions, and brand favoritism are all excuses people use to mitigate or deny the veracity of test results. We wanted ironclad proof of power, so we got in touch with Jim Bell of Kenne Bell Performance in Rancho Cucamonga, California. He agreed to perform a chassis dyno test on a bone-stock SRT Hellcat Challenger, and as you might imagine, his Dynojet chassis dyno was well up to the challenge of measuring the Hemi’s rear-wheel twist. Moreover, since Kenne Bell specializes in developing supercharger kits for all brands (including Dodge, Chevy, and Ford) Kenne Bell is an impartial observer, as their dyno data is obtained strictly for empirical testing and tuning, not bragging rights. As it so happens, Kenne Bell have tested the Hellcat’s two closest natural competitors: a ’13 Chevy Camaro ZL1 and a ’13 Shelby Mustang GT 500, both in showroom trim. This would give us a nearly perfect basis for comparison.
That said, the Dynojet at Kenne Bell is no ordinary Dynojet. In order to reduce statistical noise, this facility is hermetically stabilized at 72 degrees F and 60 percent relative humidity, and its cooling fans are calibrated to produce the same rate of flow over the front on every run. The added expense allows Kenne Bell the benefit of more granular test data, which results in more precise tuning, and higher power output for each kit they design.
Strapped to the dyno, the eight-speed automatic-equipped ’15 SRT Hellcat Challenger from Chrysler’s West Coast media fleet produced a corrected rear-wheel peak of 620 hp, happening at the fuel-limited 6,200-rpm redline in Fourth gear. (Rear-wheel torque maxed at 579 lb-ft at 4,200 rpm.) By comparison, a stock ’13 Chevy Camaro ZL1 six-speed automatic maxed out at 465 hp at 6,300 rpm (also run in Fourth gear and limited electronically by fuel), and 473 lb-ft of twist at 3,700 rpm. The completely stock ’13 Ford Mustang Shelby GT 500 was a six-speed manual trans model, and in Fourth gear, put out peaks of 587 hp at 6,400 rpm and 575 lb-ft at 4,300 rpm.
If we are to accept as fact that our press vehicle is representative of production examples—and we caution that hasn’t always historically been the case—then we can surmise that the Hellcat has a huge horsepower advantage over Chevy’s top Camaro (155 hp peak-to-peak), and a significant lead over the alpha dog Ford (33 hp peak-to-peak). From off idle, the Ford has a modest advantage, but by 3,500 rpm, the Ford’s lead has evaporated, and the Hellcat rockets away. If we bring vehicle mass into the equation, the Ford would likely eke out a slight dragstrip advantage due to its lighter weight, but there’s something we want to point out about the power curves that could prove brutal to the Ford: at the Hellcat’s fuel shut-off redline, the power curve is still pulling hard, while the Ford has flatlined. From the looks of the power curve, by simply raising the Hellcat’s rev limit to 7,000 rpm, there appears to be another 50 hp in the bank. Game over for the Ford.
For the moment at least, the Hellcat is on top. Should Ford or Chevy answer back with more powerful versions, such as the unlikely scenario of the Camaro getting the Z06’s LT4 and Chevy giving it away for the same price as the current model, then we might have a real knife fight. Until then, Hellcat is king of the street.
Want to see how it all went down on video? Head over to HotRod.com and search “SRT Hellcat Challenger Dyno Test.”
The test venue for our ’15 SRT Hellcat Challenger was the Dynojet chassis dyno at Kenne Bell Performance in Rancho Cucamonga, California.
The Hellcat Hemi officially makes 707 hp at the crankshaft, thanks to an IHI-sourced twin-screw supercharger making 11.6 pounds of boost through dual air-to-liquid intercoolers on a low-temp cooling circuit. Forged 9.5:1 pistons sourced from MAHLE run on bushed, floating pins and act on forged steel rods and an induction hardened, micropolished forged crank with select-fit main bearings. It’s all race-quality stuff that absorbs punishment with ease.
A peek under the SRT Hellcat reveals that the engine compartment is well-sealed against the elements from below, a nod to improving the aerodynamics on a car that is rated to go 199 mph. Rice racers take note: This is what real ground effects look like when you actually need them!
To keep the ABS circuit from intervening during the dyno test, Kenne Bell has learned from experience that it’s important to pull the ABS relay from the junction box. The same was done on both the Chevy ZL1 and the Shelby GT 500.
The Dynojet needs a solid tach signal from an ignition wire. Here you can see the dyno’s speed sensor is clipped to the short coil lead on top of the Hellcat’s valve cover.
Kenne Bell development engineer Ken Christley data logged our dyno runs through the Hellcat’s CAN buss. The engine run parameters were recorded to aid development of their new 4.2L “Hellcat” blower kit. This will allow naturally aspirated 392 owners to step up to 901 hp for around $7,000. We’re getting ahead of ourselves here, but the numbers pencil out like this: Buy the 392 Scat Pack Challenger for $39K, add the 4.2L Kenne Bell blower kit for $7K, and move into the fast lane for around $46K and change, all in. It’s a great alternative for those who can’t pony up for the Hellcat’s $60K right off the bat.
The Camaro ZL1 engine bay looks a lot different with the “turtle shell” removed from atop the blower. Essentially the same from the 2012 model year to the present year, the ZL1 employs a 6.2L LSA powerplant with a 1.9L Eaton blower making 7 psi. It’s rated from the factory at 580 hp and 556 lb-ft of torque.
The ’13-14 Shelby GT 500 is the most potent Mustang ever made, and features a four-valve-per-cylinder 5.8L V-8 with a 2.3L Eaton supercharger making 15 psi of air-to-liquid intercooled boost. Ford rates the GT 500 at 662 hp and 631 lb-ft of torque.
Blue line: 2015 SRT Hellcat Challenger (eight-speed TorqueFlite)
Red line: 2013 Shelby GT 500 (six-speed manual)
Green line: 2013 Camaro ZL1 (six-speed automatic)