638. That's the number of SAE-certified horsepower packed into the 2009 Chevrolet Corvette ZR1's supercharged 6.2-liter V-8, along with 604 lb-ft of torque. The supercharger has a displacement of 2.3 liters with a maximum boost pressure of 10.5 psi. The most powerful production engine to ever come out from a GM factory boasts 103 horsepower per liter and will propel the "Blue Devil" to a top speed that is well over 200 mph.

GM expects the Corvette ZR1 to be the most fuel-efficient 600-horsepower-plus car on the market, which isn't an outlandish statement considering the near-single-digit fuel economy numbers posted by the likes of the Lamborghini Murcielago LP640 and others. GM took measures to ensure that the engine would have reliability comparable to the rest of the small-block family. According to GM powertrain engine engineering executive director Sam Windgarden, "Developing the LS9 involved more than simply striving for a great horsepower number. Endurance and reliability testing have shown the engine to be robust and low-maintenance, just like other engines in the small-block family"