The Dodge Challenger and Charger Hellcat models are legendary for their monstrous horsepower figures straight from the factory. Boasting a supercharged 6.2-liter HEMI V8 engine, these cars are advertised with an impressive 707 horsepower. However, online discussions and varying dyno results often lead to confusion about the actual power output. Let’s delve into the real horsepower figures of a stock Hellcat, separating dyno myths from reality.
Decoding Dyno Results: Why Numbers Vary
When you see claims of a stock Hellcat putting down numbers significantly higher than expected at the wheels, it’s essential to consider the type of dyno used. Dynojet dynos are frequently used and tend to read higher compared to other types. Furthermore, some dyno operators might not calibrate their equipment correctly, or they may use the outdated STD correction factor. The STD format artificially inflates horsepower numbers, leading to misleading results. Therefore, claims of a stock Hellcat achieving 670 rear-wheel horsepower (rwhp) on such dynos should be viewed with skepticism. To reach 670 rwhp, a Hellcat would need a crank horsepower figure closer to 830-840, which is far beyond the factory rating.
Understanding Drivetrain Loss in Hellcats
A crucial factor in understanding the discrepancy between crank horsepower and rwhp is drivetrain loss. This refers to the power lost as it travels from the engine crankshaft, through the transmission, driveshaft, differential, and finally to the wheels. While rear-wheel-drive cars typically experience drivetrain loss, the Hellcat, with its robust components and supercharger, tends to have a higher percentage. According to Viper technicians and Mopar experts, a drivetrain loss of around 20% is realistic for Hellcats. Considering the size of the car and the power needed to drive the supercharger and other systems, this 20% estimate aligns with expectations. Applying this 20% loss to the advertised 707 horsepower results in approximately 565.6 rwhp (707 hp – 20% = 565.6 hp).
Real-World Dyno Testing on a Dyno Dynamics Dynamometer
To get a more accurate picture of stock Hellcat horsepower, it’s important to look at results from more precise dynos like Dyno Dynamics dynamometers. These dynos are known for their accuracy in measuring real-world power. One Hellcat, tested on a Dyno Dynamics dyno, registered 572 rwhp. This translates to a crank horsepower of approximately 715, which is remarkably close to the advertised 707 hp figure and well within a reasonable margin of variation. Supporting this, another stock Hellcat, tested on the same Dyno Dynamics dyno just two weeks prior, achieved 570.5 rwhp. This consistency across multiple tests on an accurate dyno reinforces the conclusion that stock Hellcats produce horsepower figures very close to the factory claims.
Drag Strip Performance as Further Evidence
Real-world performance on the drag strip also supports these dyno findings. The same Hellcat that dynoed at 572 rwhp achieved an 11.3-second quarter-mile time at 126 mph in its third-ever run, completely stock. This was achieved at a Density Altitude (DA) of 1670 feet. Correcting for sea level conditions, this translates to a high 11.1-second quarter-mile at over 127 mph. These drag strip times are even better than what professional SRT drivers have officially recorded in stock Hellcats. This real-world performance further validates that this particular Hellcat was performing slightly above average, and the estimated 715 crank horsepower aligns perfectly with this observed performance.
Conclusion: Hellcat Stock HP is Right on Target
In conclusion, while some dyno results may suggest inflated horsepower figures for stock Hellcats, accurate dyno testing and real-world drag strip performance indicate that the factory-advertised 707 horsepower is indeed realistic. Taking into account drivetrain loss and using reliable dyno equipment, stock Hellcats typically produce around 570-575 rwhp, equating to a crank horsepower figure very close to the stated 707 hp. Minor variations are expected, and some engines may even slightly exceed the official rating, but overall, the Hellcat delivers on its horsepower promise right out of the factory.
