The HUMMER H1 Alpha is the first vehicle in the HUMMER Alpha performance series designed to take HUMMER’s legendary off-road performance to a higher level. The H1 Alpha is powered by the Duramax 6600 6.6-liter turbo-diesel V8 engine combined with the Allison 1000 5-speed automatic transmission. The Duramax 6600 produces 300 horsepower and 520 lb-ft of torque which is a 46 percent increase in horsepower and an 18 percent increase in torque.