The EPA is conducting a cycle development project for heavy duty engines. Ultimately the project will produce dynamometer cycles. The data being used in the cycle development data analyses are the data collected in the CAPE-21 survey. Forty-four trucks and three buses were surveyed in Los Angeles, and forty-four trucks and four buses were surveyed in New York City. For the trucks surveyed, speed (MPH), engine rpm, road and traffic descriptions, and an engine load parameter (rail pressure for Cummins diesel engines, rack position for Detroit Diesel Allison (DDA) diesel engines, throttle position for caterpillar diesel engines, and manifold vacuum for gasoline engines) were recorded at approximately one second intervals. For cycle development, it is desirable to have the load (power) parameter in terms of % engine HP. The purpose of this report is to summarize the analyses, subsequent results, and conclusions in developing a normalized horsepower model for diesel engines.