Depending on the year and version of the 454, horsepower ratings range from 245 to 450 horsepower. The 454 was available in LS5, LS6 and LS7 versions depending on the vehicle in which it was installed.
The issue year also is important, as emission restrictions introduced in 1973 resulted in that year's LS5 having the lower horsepower rating of 245. In 1972, the year prior to a tightening of emissions standards, the LS5 pushed 360 horsepower and the LS6 reached 450 horsepower. The LS7 was not available in any cars, but it was used as a crate motor and was rated at 500 horsepower.