In 2011, Ford produced a total of 5,100 units of the Shelby GT500. Out of those, only 126 had a glass roof option, making them rare and hard to find on the market today. If you do manage to find one for sale, be prepared to pay a hefty price. Recently, someone purchased one of these 126 cars with approximately 83,000 miles on it and decided to test the engine’s power output.

The 2011 Shelby GT500 comes with a stock 550 horsepower and 515 pound-feet of torque at the flywheel. This model introduced a new aluminum 5.4-liter V8 engine that was lighter and more efficient than its cast-iron predecessor. These improvements also eliminated the US Gas Guzzler Tax for the sports car.

However, the particular car being tested is not completely stock. It has been modified with a cold air intake system, a VMP heat exchanger, and an upgraded Borla exhaust system. These enhancements allow the supercharged engine to breathe better. The car in the video is running on 93-octane fuel and has a TR-6060 six-speed transmission, which remains in its stock condition. The dyno runs are performed in fourth gear, which has a 1:1 ratio.

The best result achieved by this modified 2011 Shelby GT500 is 508 horsepower at the wheels. Taking into account the average 15-percent drivetrain loss, the peak output at the flywheel is estimated to be around 584 horsepower. This is a respectable result considering the mileage and the relatively minor modifications made to the engine. In terms of torque, it registered 484 pound-feet at the wheels, which translates to approximately 557 pound-feet at the engine, again surpassing the factory numbers.

While a dyno run is not the definitive indicator of an engine’s overall condition, it does suggest that this 5.4-liter supercharged V8 is in good health.