Section 14 - Engine Testing - Group 14 Chassis Dynamometer (14-03) M11 Page 14-37 Chassis Dynamometer (14-03) Operation The performance of an engine installed in ‘‘on-highway’’ vehicles can be tested on a chassis dynamometer. NOTE: Due to driveline inefficiencies and engine-driven ac- cessories, the rated horsepower will be reduced by approxi- mately: 20 percent for single axle vehicles 25 percent for tandem axle vehicles The net horsepower available is called wheel horsepower (WHP). NOTE: These percentages are used for engine run-in only and are not to be used as absolute figures. Caution:
Before installing or operating a vehicle on a chassis dynamometer, follow all the vehicle manufac- turer’s safety precautions. Caution: Low profile radial tires are more sensitive to heat than bias ply tires. Excessive operating time at full load can damage tires due to overheating. Check the tire manufacturer’s recommendations for the maximum al- lowable chassis dynamometer operating time.