2013 GT500 Underrated? Dyno Shows 609 RWHP

When Ford announced the 2013 Shelby GT500 back in November, the new aluminum block 5.8-liter V8 was initially rated at an astounding 650 horsepower. As if that wasn’t enough, Ford updated the rating last month to 662 horsepower and 631 lb-ft torque. However, it looks like those numbers aren’t necessarily a true reflection of the new GT500′s horsepower rating, as recently found out by Steve Turner, editor-in-chief of 5.0 Mustang & Super Fords magazine, at the press launch for the car last week.

In between laps at Road Atlanta and making passes at Atlanta Dragway, Turner managed to sneak one of the cars away for a quick dyno test and found that the 2013 Shelby GT500 put out an astounding 609 rear wheel horsepower. Factor in a fifteen percent drivetrain loss and the supercharged 5.8-liter V8 is producing closer to 715 horsepower at the crank. Even with a conservative ten percent drivetrain loss figured in, the Shelby would still be putting out over 675 horsepower, well over the official rating.

You can watch the dyno test of the 2013 Shelby GT500 in the video below.