Exhaust Gas Device Testing-Road or Chassis Dynamometer?

Sixteen vehicles, representing four different power-to-weight ratios, were tested over the California Motor Vehicle Pollution Control Board exhaust device evaluation cycle on the road and chassis dynamometer. Data are presented comparing the engine intake air consumption and the sensible heat output for both test methods.

These data indicate that the cycle, as conducted on the road, requires more intake air and rejects more exhaust heat than does dynamometer operation. The difference in exhaust heat content for dynamometer operation, as compared to road operation, increases as the power-to-weight ratio increases.

Increased horsepower settings for dynamometer testing are evaluated. With increased horsepower requirements it is possible to provide equivalent engine air consumption and exhaust heat approximately equal to road operation.